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CH1787 small footprint hardware controllable 2400bps modem introduction featur es the ch17 87 is a sm all foo t print, full function 24 00b p s , v.22bis asyn chrono us mo dem d e si gne d to b e u s e d in appli c ation s whe r e the r e is little or no e x ternal co ntro ller intelligen ce t o co mman d the mod e m. the ch17 87 allows the u s er to op erat e the mo de m via hardware resou r ces o n l y, not requiring at com m and exe c ut ion for basi c ope ration. for those appli c at ions whe r e a n external co ntrolle r is av ail able, the CH1787 ope rat e s like a sta nda rd at comma nd driven m o dem. ? suppo rts sta ndards ccit t v.22bi s, v.22, bell 2 12, and bell 103 ? fcc pa rt 68 approved an d doc a pprovable ? doe s not re q u ire a mi cro p roce ssor to op erate ? pin activated hang -up ? pin activated answe r ? manual o r igin ate and an swer pin s ? at comma n d stru cture available ? ul1 459 re co gnized ? 1000 vac i s o l ation barrie r , 1500v pe ak i s olatio n ? single 5 volt operation the ch17 87 is ideal for use a s a re mote modem in appli c ation s su ch a s ala r m prod uct s and in ind u st rial controllers. the CH1787 will di al a pre-stored telepho ne n u m ber un der p i n a c tivation control to ma ke a co nne ction with an other modem. t h e ch17 87 can also a n swe r incomi ng calls (either automatically or manually ) usi ng the an s pin. a call is termin ated by ac tivating the hng pi n. ? low p o wer sl eep mod e ? automatic adaptive a nd fixed comp romi se equali z ation ? test mod e s a nd diag no stics ? size: 2.0? x 1 . 25? x 0.53? ? nvram allo ws stora ge of custom configuration s and telep hon e numbe rs ? comm ercial operating tem peratu r e: 0 t o 70 c ? extended temperature: ? 40 to 85 c (ch178 7et) gen e ral des crip t ion of fun c tiona l bloc ks figure 1 co ntains a fun c tional blo c k diagram of the ch178 7. the CH1787 i s compri se d o f a modulato r /de m odulato r , controlle r, an fcc pa rt 68 approved telepho ne interface data acce ss arran gem ent (daa) a nd nvram. modulation/ demodula t io n and control. this function al block is co mprised of a mo nolithic m ode m integrated circuit, with built -in facilities to accommodate integrate d at comm and co ntrol an d resi dent interfa c e s for gene ral co mmuni cation and ro uting to the daa. con t roller. the controlle r is a progra mmed microprocessor th at provid es co mman d s to the modem in re spon se to external p i n activation. the followi ng pins a r e co ntrolled by the microp ro ce ssor an d are descri bed in detail i n t able 1. t hese pi ns a r e operational when the mod e m is in use at 2400b ps o n l y . ans manual a n swer pin inp u t ? answer mod e ? place s mod e m in answe r mode figure 1. ch178 7 fun ctional bloc k diagram. org manual o r igi nate pin in put ? ori g in ate mode ? pla c e s mode m in o r iginate m ode da a. t h e ch17 87 i s de signe d t o meet no rth american tel epho ne sta n dard s a s set by fcc pa rt 68 and do c. t he telep hon e line inte rface meets ul 14 59 with 1 000va c a nd 1500 volt pea k surge i s olation. as su ch, it co mplies with u.s., canadian, an d other internatio nal requi rem ents that spe c ify that level of isolatio n. th e ch17 87 i s fcc part 68 pre - ap proval. a label i s provid ed with th e re gistratio n nu mber an d rin ger equivalent (ren). t h is label shoul d be p r omin ently displ a yed on the host e quipme n t. as with mo st ora automatic di al pin input ? dials o ne of two pre - sto r ed n u m bers ba se d on tst hn g force s ch17 87 to discon n e ct aa r enable s auto answe r tst selects phon e numbe r to be diale d . work s with ora ? 2002 ce rmetek microelectronics, inc. page 1 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem cou n trie s (except the u.s.), canad a re qu ires submi s sion o f the p r od uct co ntainin g t he ch178 7 f o r do c app rov a l. this ca n be done by submitting t h e desi gn to a te st ho use o r consultant. call ce rmete k for as sist a n c e . nvr a m. nvram can save a m a ximum of four telepho ne n u m bers with u p to 36 digit s or m odifie r s in each. the at&zn = s comm and wi ll store s, the telepho ne nu mber di al stri ng. the at d t s=n command will cau s e th e ch1 787 to dial one of the four stored telepho ne n u m bers. t he nvram sto r age l o cation for the four telep hone nu mbe r s is sel e cte d by an n of 0, 1, 2, or 3. loca t ion 1 is used for the ora store d num be rs and cermete k nu mbe r . the at& w n comm and will store th e act i ve configu r a t ion in one of two nvram locatio n s as sele cted by an n of 0 or 1. the at& y n comm and sel e cts on e of th e sto r ed confi guratio ns to b e automatically re called and made active upon re set or power up. the atzn comman d im mediately re call s and activate s a stored co n f iguration. s ee t able 2 a n d 3 for storable s-re giste r s a nd com m an d s . supp orte d features at com m a n d set. a 4 0 - ch aracte r co mmand line i s sup porte d. t he comm and line start s wi th at an d m a y contai n stan dard or e n h anced comm and s. see the cermete k web s ite at http:// w w w . cermetek.com for publi c a t i o n a t comm and s and s-regi sters . serial hos t interface. the seri al in terface i s v. 24 (eia-232 -d) comp atible. see pin de scription i n t a b l e 1. speaker interfa ce. the spk output reflec ts the receiver an al og input and provide s a si gnal that can be used to monitor call progre ss. although the spk signal can d r ive a 3 0 0 ? load di re ctly, the spk sign al is usua lly input to an audio po we r amplifie r a n d the amplifi e r drives a spea ker coil. fig u re 5 sh ows how to d r ive an 8 ? spe a k e r. the sp ea ker can be turne d on a nd off with the at mn comm and. t he sp ea ker v o lume can be adjuste d by the atln comm a nd, whe r e n i s 0, 1, 2 or 3. phone contr o l. the voice/data (v/d) pin toggl es hi gh whe n the mo dem goe s off hoo k and can b e used t o activate a rel a y which can switch a tele phon e on o r off the tip and ring t e lco li nes. thi s fe ature all o ws t h e telepho ne to be discon ne cted when a data call is in prog re ss, pre v enting the d a ta from b e in g distu r be d b y an inadve r ten t telephone pi ck-up. see f i gure 2. sleep mode sleep mo de is a po we r down featu r e d e si gned to minimize po wer con s um ption. whe n activated, the ch178 7 will automati c all y enter sle e p mod e afte r a use r spe c ified perio d of inactivity. the ina c tivity cou n ter in cre m ents i n wh ole second s and i s sele cted by the ats2 4 comm and. the defaul t is 0 se con d s. the mo dem returns to no rmal o peratio n wh en a rin g sign al is re ce ived or u pon an inp u t low sign al on tx d. ats24 = 255 disabl es sle ep mode. figure 2. voice/da ta port co ntrol. a sleep out put si gnal is avail able t o control power to external d e vice s. in figu re 5, a fet controlle d by t he sleep s i gnal turns off the external s p eaker amplifier whe n the modem enters the sleep mo de. sleep mode redu ce s po wer co nsumpti on by approximately 50%. transmissio n speed. the ch1 787 can b e eit her originating (calling modem) or answeri ng (rem ote modem ).the tran smi ssi o n rate of th e ho st com p uter must be 300 , 1200, or 2 400b ps. th e ch1 787 will con n e c t at th e sele cted speed or will fall ba ck to t h e spe ed set by the remote o r answeri ng m odem (th e dt e transmissio n spe ed). the following tab l e indicate s the s p ee ds : originate speed conn ect spe e d bas e d on ans w e r speed of: 3 0 0 1 2 0 0 2 4 0 0 * 3 0 0 3 0 0 3 0 0 3 0 0 1 2 0 0 3 0 0 1 2 0 0 1 2 0 0 2 4 0 0 3 0 0 1 2 0 0 2 4 0 0 *pin activated operation at 2400bp s only. other spe e d s may be used with at comma n d operation. speed and parit y selection. before a call, the modem adj u s ts to the h o st spe e d (2400, 120 0, or 300b ps) and parity (odd, e v en, mark, space, or non e) via a ho st-init i ated traini ng seq uen ce. t h is al so sel e cts the sp eed of the data fo r origin ate call s. the ch1 787 automatically adapts to t he call er? s speed o n an swer call s. 2002 ce rmetek microelectronics, inc. page 2 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem the ch178 7 match e s the ho st?s p a rity wh en it returns status m e ssa ges to the h o s t. durin g a data co nne cti on, however, th e ch17 87 pa sses pa rity throu g h witho u t interpretation or alteration. powe r supply the ch178 7 module is a complex sub - system that m a y be treate d a s any other compon ent. special atten t ion s h ou ld be paid to th e p o we r s u pp ly con n e c t io ns . th e ch178 7 de code s an alog sign als f r o m the telep h one line that are in the milli volt rang e. all thoug h the ch178 7 is d e sig ned to wi thstand sig n ificantly ind u ced power supply noise, there is a limit. steps mu st be taken to gu arante e that powe r sup p ly noise on all sup p ly line s , i n clu d ing grou nd, do es not excee d 50 m v pea k to pe ak. any fre que ncy b e twe e n 20khz a nd 1 50 khz m u st be less tha n 50 mv pea k. if necessa ry, u s e dedi cated po wer and grou nd pla n e s . f a ilure to provide su ch op erati ng co ndition s could cau s e the ch1 787 to malfunc tion. figure 3. voice/tone injection. training the modem. t h e mod e m m u st be train ed to match the ho st?s spe ed a nd pa rity so that it is able to recogni ze se rial asyn ch ron ous com m an ds sent to it by the ho st uart. the ho st must retrain t he mod e m e a ch time a re set sign al i s ap pli ed o n rst o r after a res e t seri al comma nd. the mo dem i s train e d by se ndin g it the followin g three - cha r a c ter se que nce. the ch178 7 req u ire s a single +5v 5 % sup p ly. it is recomme nde d that by-pa s s capa cito rs be pla c e d o n the power su pply as cl ose to t he mo dem? s sup p ly inp u t as pra c tical. it is re co mmen ded that a 1 0 f electrolytic cap a cito r in p a rallel with a 0.01 f ce ra mic cap a cit o r be use d . enter: at import ant note the ch17 87 has be en fcc pa rt 6 8 a p p roved a s a data mod e m. utilization of the voice / tone port requi re s fu rth e r regi stratio n . fcc will requi re th at the sy stem, i n clu d ing th e ch178 7 an d the ha ndset or dt mf tran sceiver, adh e r e to part 68 rules. whe r e: a an d t mu st be up per ca se or lo we r ca se repre s e n ts carriage return the mod e m will respon d with one of the following status m e ssa ges, de pen di ng on wheth e r it is option ed for ab breviat ed (te r se) o r engli s h (verbo se ) status messag es. re spo n s e : 0 ters e < cr> ok < l f> ver b os e mo de m c o ntr o l the ch1 787 may be co ntrolled by sen d ing se ri al ascii comm and seq uen ces o n tx d (pin 16). after executio n of the comma nd, the ch1 787 retu rn s a seri al statu s messag e on rxd (pin 3 1 ). whe r e: represents carri age return (ascii 13) re pre s e n ts line feed (ascii 13) the ch17 87 may be retrai ned at any time whe n in idle. initializ ing the modem. before com m and s m a y be sent to the ch178 7, the modem m u st be initiali zed. this con s i s ts of two ev ents: 1) aft e r po we r-up, a hard w a r e re set pulse m u st be applie d to the mode m, and 2 ) the m odem mu st b e traine d to the ho st?s spe ed (240 0, 12 00, 300 bp s) an d pa rity (o d d , even, ma rk, spa c e o r non e). another atte ntion seq uen ce a/ is much like the at seq uen ce ex cept it rep e a ts the previously ente r e d comm and sp ecified with a n at prefix. whe n given, it mus t als o be in upper c a se ascii. no c a rriage return is nee ded. the c o mmand f o r m at po w e r-up reset. afte r a pplying p o we r to the mode m, an intern ally generated reset pul se is create d . the use r ca n also reset the mo dem extern all y by applying a high-goin g re set pul se to rst for at le ast 10m s aft e r the +5v po wer supply ha s stabili ze d. delay sendi ng comm and s to ch1 787 for 100-200 ms af ter power u p . typical com m and s con s i s t of three element s: the attention seq uen ce, the comman d s th emselve s , a n d a terminatin g carri age return . ? 2002 ce rmetek microelectronics, inc. page 3 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem figure 4. ch178 7 app lication diag ram of tes t circuit. table 1. ch178 7 pin des c ription s . p i n n a m e i / o fun c tio n 1 r i n g i / o ring . di re ct ly conne cts t o the teleph o ne line? s ring lead throu gh a u s er? s supplie d rj-1 1c jack. 2 t i p i / o tip . directly con n e c ts to the teleph one line?s tip lea d throug h a u s er? s suppli e d rj-11 c jack. 7 r x a o an alo g vo ice inject . tran sit and receive a nalo g voice si gnal . let float if n o t used. 8 d t r i dat a te rm inal rea d y input. active low. switching off a dtr ca n eith er return m o d e m to co mman d state, di scon nect pho ne call, or re set m odem. dt r sho u ld be set lo w whe n n o t use d . 9 a n s i ans. used to manually answer a n incomi ng call . input has two mode s of operatio n depe nding o n its state du ring re set. whe n ans i s lo w d u rin g reset, the ch17 87 will g o off hoo k in the answe r m o d e an d sen d an a n swe r to ne contin uou sly waiting fo r an o r igin ating tone. this mode of operation is used o n a dedicated non dial-u p teleph one line (leased line ) . whe n ans is high duri ng reset, the mod e m will initiate an an swer tone wheneve r the ans pin goe s low d u ri ng no rmal op eration. th e modem will send the an swer tone fo r 30 second s an d then stop. th e ch178 7 wil l then repe at the an swer to ne se que nce as lon g as a n s is low. 1 0 v / d o voice/data. used to swit ch b e tween tele pho n e and mode m line u s e. whe n lo w, the modem i s in the control m ode an d a voice ci rcuit ca n be switch e d out, rxa, txa when hi gh the modem i s in the data mode an d the input sh ould b e txd/txd. 1 1 r s t 1 i reset (ac t iv e high). mus t be ass e rted high for at leas t 10ms to res e t the modem. reset is then returned lo w for no rmal op eration. if no syst em reset is a v ailable, let t h is pin float t o enabl e intern al reset. 1 2 r i o ring in dic a tio n . this signal follo ws the freque n c y of the ringing sign al whi c h is typically 20 to 40 hz for 2 second s on and 4 seconds off. ? 2002 ce rmetek microelectronics, inc. page 4 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem table 1. ch178 7 pin des c ription s (con tinua tion). 1 3 c t s - clear to send . activ e lo w. out put always lo w. indi cate s ch178 7 is ready to a c ce pt data from dt e. 1 4 d s r o dat a set r e ady . lo w indi cate s h a ndsha king wit h a rem o te m odem is in progre s s, a nd/o r the data ca rri er of a rem o te modem i s d e tected. 1 5 o r a i ora (a ctive low). wh e n low, CH1787 will dia l one of two store d telep hone n u mbe r s depe nding o n the statu s of the tst p i n. the num bers are p r o g ramm ed u s i ng the at& z o comm and. a pre - sto r e d numbe r i s p r ovided to al l o w te sting. i t is in perma nent loo p b a ck answering on the second ring. the ch17 87 will m a ke up 15 attempts to connect with the store d n u mb er at 60 se co nd inte rvals a s lo ng as ora i s l o w . dcd lo w i ndi cat e s a su cc es s f ul c o nnec tion. if ora goes hi gh, no further attem p ts to connect will be m ade. if, after discon ne cting from a vali d con n e c tion, ora i s low the CH1787 w ill be unresponsive until or a is first pla c ed high th en lo w. th e f cc requi re s that automatic dia ling attempt s not exce ed 1 5 to the s a me number. 1 6 t x d i tra n smit dat a . se ri al re ceive da ta input. ma rkin g o r a bi n a ry 1 con d ition is t r an smi tted whe n a hig h is asse rted. 1 7 d i r o dir i ndi cate s wh en the txd an d rx d li nes a r e used for i n ternal ch178 7 con nectio n . wh en dir i s hi gh, v a lid data is o n rx d an d txd . when dir is l o w, th e user m a y ig nore rx d dat a and sho u ld n o t place any data on txd sin c e it will b e igno red by the ch1 787. the u s e r sho u ld monitor thi s pin or gate i t as sho w n i n figu re 4 t o preve n t da ta from be gi n erron eou sl y interp reted by the use r ?s ho st pro c e s sor. 18 irq - 4.7kw re si stor to 5v. 1 9 s l e e p o sleep . a low in dicates modem is i n low power i d le mod e . used to control power to oth e r device s . see figure 5. when the mod e m is ina c ti ve for a peri o d of time speci f ied by regist er s24 , the CH1787 will po wer d o wn to about 50% of its normal o peratin g power. i/o lin e s will become un d e fined. the factory set default for the ch1 787 is sleep m ode is inhi bi te d ( s24= 255 ). 2 0 g n d i gro u nd . 2 1 d c d o d a t a c arrier d e tec t . low indi ca tes that a dat a ca rrie r fro m a remote m o dem ha s be e n detecte d. dc d follows carrier is the default. 2 2 h s o speed indicati o n . a low o n this pin indi cate s the mode m is operating at 2 400b ps. 2 3 o r g i originate (active lo w) places ch17 87 in off h o o k mode witho u t dialing. used to o r igin ate a conn ectio n on dedi cate d lea s e d lin e s (i.e.,?dry? li nes). t he remote m ode m mu st be i n answe ring m ode. 2 4 n / c - no conn ectio n . 2 5 n / c - no conn ectio n . 2 6 n / c - no conn ectio n . 2 7 s p k o speaker . audio output. see figure 5. 28 tst i test pin i nput used i n conj unctio n with ora to stee r the di aling b e twee n a u s e r store d n u m ber ( tst lo w) a nd a pre - stored ce rmete k test numbe r ( tst high). see ora de scription. 2 9 c o n o co n in dicat e s a valid 2 4 0 0bp s con nect i on. may be use d in pla c e of dcd an d hs to s t art the comm uni cati ons o r to indi cate the sta r t of an excha n ge of data. 3 0 h n g i hn g (active low). used to force th e ch178 7 to di sconn ect. t h e hn g pin i s only fun c tion al whe n dc d is ac tive (low). 3 1 r x d o receive d a ta . se rial receive data output. re ce iv ed marking or a bina ry 1 co ndition i s indicated by a high. 32 vcc i 5 volts 5%. note: noi s e sho u ld be le ss than 50mv 3 3 g n d i gro u nd . 3 4 a a r i aa r (a ctive low). whe n asserte d lo w then high, ch178 7 will auto an swer durin g a ring cy cle. aa r can be tie d l o w prima r ily t o en able a u to answe r o n the first ring. aar will not overri de auto answe r co ndi tion e.g., s0 1. spare pins a r e av ailable for custom fu nctions . co ntac t ce rmetek w i th y our requiremen t s. note: (1) if v cc has a s l ow power up ramp ti me, the internal reset may be ineffective. 2002 ce rmetek microelectronics, inc. page 5 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem at [comma nds] . wh ere r e pr es en ts carria ge return (ascii 1 3 ). wh en entering comma nd s to the ch17 8 7 , the backsp a ce cha r a c ter ctl h (ascii 8) can be use d to edit mi st ake s . at and a/ m a y not be edited. multiple co mman d s may con c aten ated on a singl e comm and li ne. co mmand line s may not exce ed 4 0 ch ar ac te rs , e x c l ud in g at . t he comm and string belo w in stru cts the ch1 78 7 to train it self, to not echo cha r a c ters in the com m and mode e0 a n d then go to t he answe r mod e a . enter: ate0 a< c r > re spo n s e : ok at comma nd d a ta r a te with the se ri al interfa c e, t he rate is sp eed sen s e d for parity and format. at command s e t the comma n d set i s divide d into thre e types as li sted i n table 2: b a si c comm and s, dial modifie r s an d ampe rsand comman d s. the stat us mess ages the ch1 787 respon ds with a status messag e after each com m a nd is exe c ute d . this statu s messa ge m a y either be a si ngle di git follo wed by a carriage return o r a carria ge retu rn and line fee d with a me ssag e in engli s h, followe d by a carria ge retu rn and line fee d . the ba sic sta t us co de su b s ets a r e en a b led with the xn comm and. whe r e n=0,1,2,3,5 the status cod e s can be in messa ge f o rm o r re sult cod e s sele cted for the fi ve xn comma nd s. x0 ? result cod e s 0, 1, 2 , 3, 4 x1 ? result cod e s 0, 1, 2 , 3, 4, 5, 10 x2 ? result cod e s 0, 1, 2 , 3, 4, 5, 6, 10 x3 ? result cod e s 0, 1, 2 , 3, 4, 5, 7, 10 x4 ? result cod e s 0, 1, 2, 3, 4, 5, 6, 7, 10 (facto ry default) modem s t ates. the ch17 87 may be in either the comm and m ode or the data mode. when the ch1 787 is idle, it is in comm and m ode by defa u l t. when a d a t a transmissio n is in progress, the CH1787 is in data mode a nd will not recog n ize comm a nds. th e h o st system must send an ?esca pe se q uen ce? to the ch178 7 forci ng it o u t of t he data m o d e an d into th e comm and m ode befo r e co mmand s will be acce pted. escape seq u ence. the escap e seq u ence co nsi s ts of a guard time (a pe riod wh ere no cha r a c ters are sen t to the ch17 87 ) followe d by 3 escap e cha r acters, follo wed by a g uard ti me. at po we r-u p, the gua rd time i s set t o 1 se con d (mini m um), and th e escap e ch a r acte r is set as ?+.? th ese p a ram e ters ca n be modified via re giste r s s2 and s12, re spectively. the CH1787 will stay off-hook with it s carrier on af ter the escap e seq uen ce is received. it return s an ok status m e ssa ge wh en it is ready to accept comm an ds. the data m ode i s ree n t ered by i s suing th e at o comm and. resul t statu s messa ges meaning 0 o k comm and ex ecute d . 1 con n e c t carrie r dete c ted at 300b ps. 2 r i n g ring d e tecte d . 3 no carrier did not dete c t carri er. 4 e r r o r entry erro r . 5 con n e c t 120 0 carrie r dete c ted at 1200 bp s. 6 no di al tone off-hoo k, but no re spo n se af t e r 5 se con d s. 7 busy busy sign al d e tected. 10 con n e c t 240 0 carrie r dete c ted at 2400 bp s. dial modifier s function p p u l s e d i a l r originate call in answer mode t touch ton e dial w wait for di al tone ; return to idle state @ wait for quiet ans w er comm and ! f l a s h hoo k , p a u s e 0-9/ a,b,c,d dial di gits/ch a ra cters at comma nd ap plic ation s dial a number. the di al com m and take s the form dn , whe r e n is a strin g of characte rs. in the simplest form, n will only the digit s of the phone num ber to be dialed. example: di al numbe r enter: at d 1 2345 67 in re spo n se to this com m and, the ch17 87 di als the telepho ne n u m ber ?1 23-4 567? an d the n wait s fo r the carrie r from the remote modem. if no carri er is detecte d within a given time (the d e fault time i s 30 se con d s), the ch17 87 a u tomatically relea s e s the l i ne and sen d s a no carrie r result co de . if a ca rrie r is detecte d, the CH1787 i ssues a co nnect re sult code and goe s on -line, permitting comm uni cation with t he remote modem. ? 2002 ce rmetek microelectronics, inc. page 6 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem the dial co mmand may also be issued without a telepho ne n u m ber. the atd comma nd cau s e s t he modem to pi ck up th e tel epho ne lin e without di alin g a numbe r. table 2. ch178 7 regi ster summar y . regis t e r f u n c t i o n s0* ring to answer on s 1 r i n g cou n t s2 esca pe code characte r s 3 c a r r i a ge retu rn charac ter s4 line fee d ch ara c ter s5 bac k space charac ter s6 wait for di al tone s7 wait time for data carrier s8 pause tim e for co mma s9 car r ie r dete c t resp on se t i me s10 lost carrier t o han g -u p delay s 1 1 d t m f dialing s p e e d s12 esca pe code guard ti me s14* bit mapped o p tions regi st er s16 modem te st option s s 1 8 * t e s t time r s21* bit mapped o p tions regi st er s22* bit mapped o p tions regi st er s23* bit mapped o p tions regi st er s24 sleep mod e inactivity time s25* delay to dt r s27* bit mapped o p tions regi st er s28* bit mapped o p tions regi st er *= s-regi ste r stored in nv ram up on re ceipt o r & w comm and. using th e pause ch arac ter. when pla c ing a call fro m an offic e with a telephone c o nnec ted to a pbx, it may be ne ce ssa r y to dial an a c cess co de (usu ally the di git 9) to g e t an outsid e line. inse rting a comm a in t he telepho ne nu mber di re cts the ch178 7 to pause for a spe c ific len g th of time. t he fa ctory d e f ault pau se time is 2 se co nd s. example: di al 9, pause, and dial num b e r. enter: atdt9,12 34 567 re spo n se: dial tone, dt mf tone gen eration multiple co m m as may be use d to inc r eas e delay time. touc h tone an d pu lse dialin g the ch1 787 can use dtmf (tou ch -tones) o r di al pulses whe n dialing a tel epho ne num ber. if the dial comm and d oes n o t spe c ify which type to use, the ch178 7 defa u lts to the typ e la st spe c ifi ed. the power- on default val ue is p . example: pulse dial 9, pause, an d touch-to ne dial numbe r. enter: atdt9,12 34 567; re spo n se: dial to ne, dt mf tone s, ret u rn to comm and state enter: atdp 9t12 34 567 re spo n se: dial tone, pul s e diali ng s0 do not answer tele phone s1 answe r on ring 1 originate a call in answ er mode. the d comm and force s the ch17 87 into origin ate mo de. to call an origin ate-only modem, dial the numb e r and set the modem to an swer mo de via the r (rev e rse origi nat e). enter the r co mman d a t the en d of the tele pho ne numbe r. s2 answe r on ring 2 s3 answe r on ring 3 whe n s0 is set to 0, the m odem will n o t auto-a n swe r . example: assign the va lue 6 to s0 t o set the CH1787 to answer o n the sixth ring. redial las t number. us e a/ , the repeat comm and , to redial the l a st telepho ne numbe r diale d when a b u s y sign al is re cei v ed. enter: ats 0 =6 re spo n s e : ok return to command state. the ch17 87 can be force d to re enter the comman d sta t e after diali ng (witho ut h ang ing u p ) by e n d ing th e di al comm and wit h a semicolon. thi s i s u s efu l wh en usi ng the ch1 787 as an auto dial er. con n ecti ng t o the host uar t since the ch17 87 com m unicates d a ta se rially and most h o st produ cts h andl e data i n a p a rallel form at, a uart is ne e ded to ma ke parall e l-to -serial an d se rial-to- parall e l tran sl ations. automatic ans w e r ing. the s0 regi ster co ntrol s t h e numbe r of ri ngs that mu st o c cur bef ore th e m o d e m answe rs a cal l . the regi ste r may ra nge i n value from 0- 255. the serial interface lin e s. the ch17 87 su ppo rts t he full rs-232 c/v.24 se rial i n terface. si gnal l e vels a r e ttl rathe r than rs-2 32 c level co mpatible, wh ich allows the user to di re ctly con n e c t the ch178 7 to t he host? s uart without ne edi ng level tran slating circuit r y. example: touch-to ne dial 9, p a u s e, di al nu mber, return for co mmand. ? 2002 ce rmetek microelectronics, inc. page 7 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem table 3. ch178 7 at command s e t summar y . basic c o mmands function a t a t t e n t i o n cod e a a n s w e r com m a n d a/ rep eat la st comm and *bn comm uni cati ons stand ard option d d i a l c o mma n d *e off-line cha r acter e c ho o p tion hn switch hook control option *ln speaker volu me option * m n s p e a k e r cont rol o p t i o n o n o n - l one co m m a n d p p u l s e d i a l *qn re sult co de dis p lay optio n sn selec t an s regis t er sn= write to an s regi ster sn? rea d an s registe r *vn re sult co de from o p tion *xn re sult co de set/call prog ress o p tion +++ esca pe code sequen ce , p a u s e ? returns l a st addre s sed s regi ster *yn long spa c e disco nne ct o p tion fn on-li ne echo characte r o p tion z r e s e t ampers and c o mmands function *&dn data te rmina l ready optio n &f load fa cto r y default s *&gn guard ton e option *&pn mak e to break ratio selection *&sn data set ready option &tn test comma nd option &v view active config uratio n *&wn store ac tive profile *yn recall active profile *&zn store telep h one numbe r s * & c n n o t suppo rte d percen t c o mmands function % d n d t m f attenu a t i o n %j load se con d a ry facto r y defaults *= co mman d s that can b e store d in nv ram. note: refer to cermetek publi c a t i o n a t c o mmand s and s-re gist ers for a det ailed di scu s sion of para m eters in table 2 and 3. two of the s e lines are all that are req u ired fo r pro per ch178 7 op eration: txd , rxd and dt r . the modem is cont rolled by se ndin g it se rial comm and s ove r txd and can be monitore d by serial st atus me ssag es returned o n rxd . all other seri al interface li nes m a y be utilized for the conve n ien c e of your appli c ati on but are not req u ire d by the modem. unu s e d outp u ts (form mo dem) sho u ld be left unconn ected. unu s ed input s sho u l d be tied to t he prop er lo gic l e vel. see pin descriptio n . figure 5. speaker con t rol. circuit allo w s call progre ss mo nitoring. phone li ne connec tion guideli n es 1. the mo untin g of ch17 8 7 in the fin a l asse mbly must b e ma d e so t hat it is i s olate d from exposure to any hazardo us voltage s within the assembly. adequate se paratio n a n d re straint of cabl es and cor d s m u st b e prov ide d . 2. the circuitry f r om th e ch1 787 to the tel epho ne lin e interface m u st be provid ed in wiri ng th at ca rri es n o other circuitry than that s pecifi c ally all o we d in the rule s (su c h a s a and a1 le ads). 3. con n e c tion to phone lin e sho u ld be m ade thro ugh an rj-1 1 jack. 4. tra c e s from t he mod e m? s ring and tip pins to th e rj-11 ja ck must excee d 0.1 in ch sp acin g to one anothe r an d 0.2 inch sp a c ing to all other traces. the trace s should have a nomin al wi d t h of 0.020 inch es o r gre a ter. 5. the ring a nd tip tra c e s shoul d b e as sho r t a s possibl e an d orie nted to preve n t co upling othe r high sp eed o r high freq ue ncy sig nals o n to the host cir c uit ca rd. 6. no a ddition al circuitry oth e r than th at sh own i n the followin g fig u re m a y be con n e c ted betwe en the modem mo du le and rj-11 jack. 7. the ch178 7, the rj-1 1 jack, the interfa c ing circuitry and trace s in bet wee n , must be mounte d on a circuit board with a 94 v-0 flammability rating. 8. the su pplie d fcc regi stration la be l must be applie d visibl y on the outsi de of the host produ ct. ? 2002 ce rmetek microelectronics, inc. page 8 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem t y pe of serv ice: the (i nse r t your produ ct name ) is desi gne d to be u s e d o n stan dard d e vice tel eph one lines. it con nect s to the t e leph one li ne by mean s of a stand ard j a ck called the usoc rj-11c (or us oc fj45s ). co nne ction to teleph one -co m pany-provid ed coin service (central office im pleme n t ed sy stems) is prohi bited. con n e c tion t o pa rty line s se rvice (ce n t ral office implem ented system s) i s prohibite d. conn ectio n to party lines s e rvic e is s u bjec t to s t ate tariffs . 9. the ho st pro duct? s use r manual m u st provide the u s er w i th instr u c t io ns for c o nn ec tio n an d us e as recomme nde d in section f cc regi strati on. mountin g the mode m the mod e m contain s static-sen sitive device s a nd sho u ld only be handle d by personn el and in area s that are p r op erly prote c ted ag a i nst static di scha rge. telephon e company pr ocedur es: the goal of the telepho ne co mpany is to provide you with the best servi c e it can . in order to do this, it may occa sio n a lly be n e cessa r y for them to ma ke ch ange s i n th eir equipm ent, the telephon e company will g i ve you notice, in writing, to allow you to make a n y ch ange s ne ce ssary to maintain uninterrupted servic e. there a r e two mo u n ting techni que s that are recomme nde d for physi ca lly conn ectin g the m odem to your ci rcuit card; 1) so cket s, and 2 ) dire ct sold erin g. the sockin g approa ch to mounting eli m inates cle a n ing and de sold eri ng con c e r n s . when the so cket is use d , it must ma ke a solid con n e ction to all modem pin s . failure to do so will cause unreli able m o dem operation. also, st eps should be taken to assu re that the mo d u le remai n s tight ly seate d in the so cket after the h o st prod uct is shi pped. if problems arise : if any of your telephone e quipm ent is n o t o perating p r o perl y , you shou ld imme diat ely remove it fro m your telep hone line, a s it may cause harm to the telephon e netwo rk. if the teleph one comp any n o tes a p r ob lem, they may temporarily discontinue service. when prac ti cal, they will notify you in advan ce o f this di sconn ection. if a d vance notice is not feasible, you will notified, you wil l be given t he oppo rtunity to corre c t the p r oble m and i n formed of yo ur right to file a complai n t with the fcc. contact your telepho ne co mpany if yo u have any que stion s ab out your pho ne li ne. fcc re gis t ration the ch17 87 is regi stere d with the fcc (fed eral comm uni cati ons com m ission ) un de r part 68. to maintain the validity of the regi stratio n , you must se rve notice to the end user of the p r od uct th at co ntain s t he modem of se veral re stri ctions the f c c place s on t he end u s e r of t he p r od uct th at contai ns the mo dem a nd its use. the following notice is recommen ded and sho u ld be i n clu ded in the ho st produ ct?s user manual. also, the fcc requi res that cermete k ma ke all rep a irs to the modem. if repair i s necessa ry after the mode m i s in stalled i n your p r od uct and ha s b e e n delivere d to your cu sto m er, the m odem m u st be returned to you wh ere it can be re mov ed from the h o st prod uct an d the forwarded to cerm etek f o r re pair. in the event repairs are ev er n eed ed o n the (in s e r t yo ur prod uct nam e), they sho u ld be prefo r med by (in s ert your comp an y name) or a n autho ri zed rep r e s entativ e of (insert yo ur company nam e). f o r i n formation conta c t: (insert your company ad dress). for y o u r user? s ma nual fcc pa rt 68 rul e s re quire the follo win g (o r e quivale nt) informatio n b e provided to the en d u s e r of e quipm e n t contai ning a daa. chan ges in attestation procedure for plugs and jack s (na m e of ap plica n t) atte sts that th e n e t work inte rfa c e plug s or jacks use d on this equip m ent comply with and will continue to com p ly with t he mechani cal requi rem ents spe c ified in part 68 , subpart f, specifically the di mensions , tolerances and met a llic plating req u i r eme n ts. the com p lia nce of the s e connectors will be assured by purchase specifications and in comi ng in spe c ti on. do cumentation of su ch spe c ifica t ions an d/or insp ectio n s will be provided by the fcc within 30 d a ys of their requ est for t he same. ? 2002 ce rmetek microelectronics, inc. page 9 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem p s t n pr ote c tion re q u ir em en ts b. in most environm ents, 2 termina l surg e sup p re sso r s are ad eq uate. for severe environ ment s, use an external 3 terminal device with a n earth g r ou n d . 1. curre ntly limiting pstn protec tion line dev i ce. curre n tly limiting device s are ma ndato r y to meet ul safety standa rd s. to maintain co nveyed fcc part 68 a pproval, the cu rrent limiting comp one nts identified as f1 a nd f2 i n dashed box #1 m u st also survive f cc part 68 surge testing. refe r to cermete k a pplication note #12 6 , s u p p l e m e n t a l pstn line protectio n , for more details . refer to applicatio n n o t e # 1 3 0 , s u m m a r y o f r e c o m m en d supplie rs , fo r a li st of supp liers an d a ssociate d p a rt numbe rs. 3. emi/rfi suppression. no exte rnal emi/rfi noise su pp re ssi o n ci rcuitry is requi re d to maintain conveyed f c c part 6 8 approval. ho wever, a dditional su ppre s sion, if requi re d for other rea s ons, may b e added a s descri bed b e low in s e ction s 3a-3b witho u t adversely affecting f cc p a rt 68 app rov a l. a. a ptc (rat ed at 0.15 amps) is prefe rre d becau se it re sets auto m ati c ally u pon re moval of the cu rrent flow. non -re settable dev i ces are also a c cepta b le. refer to applicatio n note #130 fo r a com p lete li st of re co m m ende d vendors an d asso ciated p a rt numb e rs. a. to p r ovide a dequ ate emi/rfi sup p re ssion, the cap a cito r/ind u ctor net work contai ned in dashed box #3 sho u l d be located as clo s e to th e rj1 1 ja ck as p o ssible. furthe r, this network sho u ld be provided with an ex ce llent gro und path to t he cha s sis. b . re sist o r s (1 0 ? carbon film or 1/8 watt minimum ) ma y be used in can ada, as can ada has n o re qui rements th at pstn equi p m ent be operational af ter a type b surge test. b. cap a cito rs c1 and c2 sh ould not exce ed 0.005f. the y must have a rating of 1. 5kv and typically a r e 0.001f 2 0 % . indu ctors l1 an d l2 may be either individua l inducto rs o r a dual indu ctor. re fer to appli c a t ion note #1 30 for a compl e te list of recom m ende d vend ors and asso ciated p a rt num be rs. for ul appli c ation s , cho o se capa citors a nd i n ducto rs that are ul 1950 liste d. th e a c t ual valu es of the comp one nts use d may vary depe nding on the end produ ct d e sig n . c. although cs a cs-03 part 1 (cana da ) follows the re quire ments of f c c part 6 8 (usa ), cermete k recom m en ds conta c ting dot (ca nad a) an d/or a ce rtified ind epe nde nt lab to verify com p lia nce. fo r can ada, u s e eith er 1 0 ? resi sto r s (ca r bon film or smd p a rt s 1 / 8 watt minimum ) as descri bed in para g raph b above. 2. ov er voltage and lightn i ng protec tion. a. surge p r ote c tion i s p r ovided by internal circuitry (see figure 3). no additional external comp one nts are req u ired t o maintai n co nveyed fcc pa rt 68 approval. figure 6. telephon e inter f ac es. 2002 ce rmetek microelectronics, inc. page 10 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem default sta t us, perform a nce, and specs defa ult con f igura t ion profile a s y n c mo de sele ct ed 2400 bp s bell 212a op eration at 12 0 0bp s even parity auto answe r disa bled comm and e c ho on all result cod e s en able d - e x tended wait for dial t one befo r e di aling - 2 seco nds det e ct s bu sy sign al full word result codes pulse dial m a ke/brea k ratio = 39/61 dsr en able d modem e nabl ed dt r dcd en abled speaker e n a b led but off when re ceivin g carrier speaker volu me set to me dium local modem will grant rdl request from rem o te modem guard tone s disa bled minimum dt r pul se wi dth = 0.1 se con d s ring cou n t ? 01 (ch1 786 ) esca pe code cha r a c ter = 4 3 carria ge retu rn ch aracte r = 13 line feed cha r acte r = 1 0 back spa c e chara c te r = 08 duration of wait for dial tone = 02 secon d s duration of wait for carrie r after dialing = 30 se con d s duration of d eal pul se (co mma) = 02 se con d s carrie r dete c t resp on se tim e = 0.1 se co n d s esca pe code guard time = 1 se con d length of u s e after comm a = 2.0 se co nd s last carrier to hang up d e la y = 0.1 secon d s dtmf inte rdi g it delay = 0.1 se con d s dtmf attenu ation = -4 db sleep mod e inactivity time = 5 se co nd s long spa c e d i sconn ect di sabled ? 2002 ce rmetek microelectronics, inc. page 11 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem table 4. CH1787 s y st em data mo de compatibilit y specifications. p a r a m e t e r s p e c i f i c a tio n p a r a m e t e r specifica tio n asynch ro nou s 2400, 1 200, 600b ps ch ara c ter asyn chrono u s . 0 - 300b ps asyn chrono u s re ceiv e c a r r i e r freq uen cie s v.22bis, v.22 , 212a origin ate+hz 2400 hz +7 hz answer 1200 hz +7 hz a s y n ch ro nou s speed rang e txd may diff er +1%, -25 % from modem o u tp ut. offsets will be corre c ted by addin g /deleti ng stop bits . bell 103 answer ? s pa ce? 2025hz +7 hz answer ?ma r k? 2225hz +7 hz originate ?space? 10 70 hz +7 hz origin ate ?ma r k? 1370 hz +7 hz a s y n ch ro nou s format 8, 9, 10 bits, i n clu d ing sta r t, stop, parity re ceiver se n s itivity o ff to on th reshold -43 d a m on to off th reshold -48 d a m teleph one li ne interface two - wi re full duplex over public swit che d net work. on -chi p hybrid and billing d e l a y timers. modulatio n v.22bis, 16 point qam at 600b aud. v.22 and 2 212a, 4 point, dpsk at 60 0ba ud . 103 binary ph ase coh e re nt fsk. hysteresi s 2 d b minimum self tes t pattern gene rato r a lternate ?on e s? an d ?zeros? an d error dete c to r, to b e use d alo ng with mo st loopba cks. a numbe r indicating th e bit e r rors d e tected is s e nt to dte. line equali z a t i o n fixed com p romise e qual ization, transmit. adaptive equ a lizer fo r psk/qam, rec e ive. transmit carrier freq uen cie s v.22bis, v.22 , 212a origin ate 120 0hz +.01% answer 240 0hz +.01% diag no stics available local analo g loopb ack. local digital loopb ack. reques t remote digital loopbac k . local interfa c e loo pba ck modem with s e lf-tes t. bell 103 mod e origin ate ?sp a ce? 1 070 hz +.01% origin ate ?ma r k? 127 0hz +.01% answer ? s pa ce? 2025hz +.01% answer ?ma r k? 2225hz +.01% call pro g re ss tones dete cted comp uter int e rface with spe a k e r or q u iet sc reen messag es (no di al tone , busy, ring -ba c k, modem an swer tone and voice). ibm px/xt/at bus co mpatible with an 8250/16 4 50/165 50a uart a s a serial controlle r. ? 2002 ce rmetek microelectronics, inc. page 12 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem table 5. ch178 7 electrical specifi cation s . t a =25 c sy m b o l c h a r acteristi c m i n . t y p . m a x . u n i t s v cc s u p p l y v o l t a g e 4 . 7 5 5 . 0 5 . 2 5 v i cc s u p p l y cu rre n t off hook op erating cu rrent on hoo k op erating cu rrent powe r do wn operating current 50 40 16 75 ma ma ma v ol output lo w voltage (i ol =0.4ma) co n (i ol =5.0ma) dir (i ol =1.6ma) sleep, dsr, dcd, hs, rxd (i ol =4ma ) v / d 0.3 0.3 0.4 0.26 v v v v v oh output hig h voltage (i oh =0.2ma) co n, dir (i hl =-1 00ua) sleep, dsr, dcd, hs, rxd (i ol =0. 4 ma ) v / d 4.45 2.4 4.18 v v v v il input low vol t age tst, org, ora, hng, aar, ans dtr, tx d 0.95 0.8 v v v ih input high vo ltage tst, org, ora, hng, aar, ans dtr, tx d 3.3 2.4 v v vt+ pos i tive hys t eres is thres o ld for res e t pin 2.7 v vt- neg a tive hysteresi s th re sold for re set pin 1.6 v table 6. ch178 7 electrical specifi cation s . p a r a m e t e r m i n i m u m t y p i cal maximum u nit s c o m m e n t s ring voltag e loop 40 vrms return lo ss @ 100 0 hz 17 db 600 ? ring f r eq uen cie s 15.3 68 hz tran smit lev el -11 dbm 600 ? ? data mode comm and m ode after re set 5 se c delay inter cha r a c t e r del a y 20 mse c between all comman d ch aracters comm and delay 100 mse c between all a t comm and s minimum reset pulse 5 mse c if user suppli ed table 7. othe r perfor mance speci fication s . p a r a m e t e r m i n i m u m t y p i c a l maximum u nit s c o m m e n t s dtmf t w ist (balance) 3 db dtmf to ne duration 50 255 ms 95ms d e fault pulse di aling rate 10 20 pps 10pp s defa u lt pulse di aling make/b rea k 39/61 % us, cana da default pulse di aling make/b rea k 33/67 % uk, hong ko ng pulse interdig it interval 700 3000 ms 789m s defaul t call pro g re ss passb and f r eque ncy 120 620 hz wait time for dial tone 2 255 se c two se cond default table 8. product f a mily summar y . model feature sum m ar y opera t ing t e mpera t ure ch178 7 fcc pa rt 68 approve d , ul 1459 regi ste r ed 0c to +70 c ch178 7et fcc pa rt 68 approve d , ul 1459 regi ste r ed -40 c to +85 c 2002 ce rmetek microelectronics, inc. page 13 document no. 6 07-0002 revision b (03/02 )
cermetek microe lectronics, inc. CH1787 small f ootprint ha rd w a r e controllable 24 00bps modem ? 2002 ce rmetek microelectronics, inc. page 14 document no. 6 07-0002 revision b (03/02 ) figure 7. ch178 7 ph y s ical di mens ions and pin function s. packag e co nnec t ion ta ble p i n n o . f u n c t i o n p i n n o . f u n c t i o n 1 r i n g 1 8 i r q 2 t i p 1 9 s l e e p 3 n o t pop u l a t e d 2 0 gn d 4 n o t pop u l a t e d 2 1 dc d 5 n o t pop u l a t e d 2 2 h s 6 n o t pop u l a t e d 2 3 o r g 7 r x a 2 4 n / c 8 d t r 2 5 n / c 9 a n s 2 6 n / c 1 0 v / d 2 7 s p k 1 1 r s t 2 8 t s t 1 2 r i 2 9 co n 1 3 c t s 3 0 h n g 1 4 d s r 3 1 r x d 1 5 o r a 3 2 v c c 1 6 t x d 3 3 g n d 1 7 d i r 3 4 a a r cermetek res e rves the rig h t to make c han g e s in sp ecific ati ons at a n y tim e an d w i th out notice. t he inf o rmatio n furnis hed b y cer me te k in this pub licati on is bel ieve d to be acc u rate and r e li abl e. ho w e v e r, no r e spo n sib ilit y is assume d b y cermetek for it s use, or f o r any infrin geme n ts of pate n ts or other ri ghts of thi r d parti es res u l t ing from its us e. no lic ens e i s grant ed un de r an y pate n ts o r p a t en t ri gh ts of cermetek. printed i n u.s.a 406 tasman d r ive | sun n y v a le ca 94089 | local: 408-7 5 2 -5000 | t o ll f r ee: 1-800 -882 -6271 | fax: 4 08-752 -5004 w e b s i t e : h t t p : / www.cermet ek.com | e m a i l : s a les@cermetek.com

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