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ELM303 Camcorder Time-Lapse Control
Description
The ELM303 is a specialized circuit for creating time-lapse videos on suitably equipped camcorders. The camcorder to be controlled must have a Control L (LANC) port, and also be capable of responding to power control signals. This is usually only available with the mini DIN connectors, and not the 2.5mm stereo plug interfaces. The ELM303 provides intervals of 10 minutes to 24 hours between recordings, without requiring any external timing components. Recording durations of either 1 second or 10 seconds is also selectable. One additional feature allows manually triggered recordings to be initiated when all three interval inputs are at a low level. Recording will begin immediately and will continue as long as the inputs remain low. This combination is fully debounced, simplifying the interface to mechanical switches. The ELM303 has been `hard-coded' to send the Control L hex command `33' (word 1) to device `18' (word 0), and cannot be modified. Be sure to verify that these are appropriate for your camera before committing to any designs.
Features
* Delays of 10 minutes to 24 hours with no external timing components * Recording durations of 1 or 10 seconds * Low power CMOS design - typically 1mA at 5V * Security feature allows on demand recording * Initial recording after 1 minute to verify system operation and connections * Pulsed power output to control camera power
Connection Diagram PDIP and SOIC (top view)
VDD I2 I1 I0
1 2 3 4
8 7 6 5
VSS LANC Power D0
Applications
* Time-lapse video recording * Security monitoring * Long period time delay circuits
VDD
Block Diagram
Control L Driver D0 Programmable Delay I2 I1 I0
2 5 7
LANC
I2 L L L L H H H H
I1 L L H H L L H H
I0 L H L H L H L H
Interval continuous 10 min 30 min 60 min 3 hrs 6 hrs 12 hrs 24 hrs
VSS
Control
VDD
VDD
3
200ms Pulse Generator VSS
6
Power
Table 1
4
ELM303DSA
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ELM303
Pin Descriptions
VDD (pin 1) This pin is the positive supply pin, and should always be the most positive point in the circuit. Internal circuitry connected to this pin is used to provide power on reset of the microprocessor, so an external reset signal is not required. Refer to the Electrical Characteristics section for further information. I2 (pin 2), I1 (pin 3) and I0 (pin 4) The time interval between each recording is determined by the logic levels at these pins, as shown in Table 1. The I0 input on pin 4 has a high value pullup resistor to simplify wiring in some instances (see the Example Applications). D0 (pin 5) This input is used to select the recording duration (time between start and stop commands). A high
level results in a nominal time of 10 seconds, and a low level provides 1 second. Power (pin 6) This is an open drain output that is driven low at the beginning and end of each recording cycle in order to toggle the camcorder power on and off. This output is generally connected to pin 3 of the mini DIN Control L connector. An internal pullup resistor is provided for a nominal drain load. LANC (pin 7) This is the open drain Control L (LANC) interface pin. An internal pullup resistor is provided for a nominal drain load. VSS (pin 8) Circuit common is connected to this pin. This is the most negative point in the circuit.
Ordering Information
These integrated circuits are available in either the 300 mil plastic DIP format, or in the 200 mil SOIC surface mount type of package. To order, add the appropriate suffix to the part number: 300 mil Plastic DIP............................... ELM303P 200 mil SOIC..................................... ELM303SM
Absolute Maximum Ratings
Storage Temperature....................... -65C to +150C Ambient Temperature with Power Applied....................................-40C to +85C Voltage on VDD with respect to VSS............ 0 to +7.5V Voltage on any other pin with respect to VSS........................... -0.6V to (VDD + 0.6V)
All rights reserved. Copyright (c)1999 Elm Electronics. Every effort is made to verify the accuracy of information provided in this document, but no representation or warranty can be given and no liability assumed by Elm Electronics with respect to the accuracy and/or use of any products or information described in this document. Elm Electronics will not be responsible for any patent infringements arising from the use of these products or information, and does not authorize or warrant the use of any Elm Electronics product in life support devices and/or systems. Elm Electronics reserves the right to make changes to the device(s) described in this document in order to improve reliability, function, or design. ELM303DSA
Note: Stresses beyond those listed here will likely damage the device. These values are given as a design guideline only. The ability to operate to these levels is neither inferred nor recommended.
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ELM303
Electrical Characteristics
All values are for operation at 25C and a 5V supply, unless otherwise noted. For further information, refer to note 1 below.
Characteristic
Supply voltage, VDD VDD rate of rise Average supply current, IDD Input low voltage Input high voltage Internal pullup resistances (see note 3) Output low voltage Circuit timing Power Pulse Control L bus
Minimum
3.0 0.05
Typical
5.0
Maximum Units
5.5 V V/ms
Conditions
see note 2
1.0 VSS 0.85 VDD 300 20 500 30
2.4 0.15 VDD VDD 600 50 0.6
mA V V K K V msec baud Pin 4 (I0) Pins 6 (Power) and 7 (LANC) Current (sink) = 8.7mA VDD = 5V (see note 4) VDD = 5V (see note 4)
180
200 9600
220
Notes:
1. This integrated circuit is produced with a Microchip Technology Inc.'s PIC12C5XX as the core embedded microcontroller. For further device specifications, and possibly clarification of those given, please refer to the appropriate Microchip documentation. 2. This spec must be met in order to ensure that a correct power on reset occurs. It is quite easily achieved using most common types of supplies, but may be violated if one uses a slowly varying supply voltage, as may be obtained through direct connection to solar cells, or some charge pump circuits. 3. The value of the internal pullup resistance is both supply and temperature dependent. 4. Circuit timing is affected by supply and temperature variations as shown in Figure 1 below. Results shown are average values that can be expected.
-6
fast
-4 -2
% Error
0 +2 VDD = 5V
slow
+4 +6 VDD = 3V 0 40 Temperature (C) 80
-40
Figure 1. Average Timing Error
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ELM303
Functional Block Diagram
The operation of the ELM303 can best be described through the following block diagram. All of the main functions are shown, while initialization, timekeeping, etc. are implied. The power on and off delays are internally set, and are not adjustable. Note that on powerup, and after responding to a `000' interval code, the circuit always initiates a record cycle after one minute. This allows the operator to verify that the system is operating properly.
PowerUp Loop wait 1 minute
wait for timeout or I='000'
Save the state of all pins
Pulse Power for 200msec
no
Control L bus active ? yes send 0x1833 to the camcorder
wait 10 sec
if D0=0, wait 1s else wait 10s yes
no send 0x1833 to the camcorder
Is I='000' ?
yes
Was I='000' ? no send 0x1833 to the camcorder
wait 5 sec
Pulse Power for 200msec
wait 5 sec
Go to PowerUp
Pulse Power for 200msec
Go to Loop
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ELM303
Example Applications
+5V The circuits on this page show two different configurations for the ELM303. In each case, one should keep in mind that these are experimenter circuits that require some extra care to protect against electrostatic discharge, etc. The other concern is the possibility of backfeeds from the two different power supplies (camcorder and ELM303). To prevent damage to the ELM303, always make sure that it is powered up before connecting to the camcorder. Figure 2 at the right shows the ELM303 in a typical security configuration. The internal pullup resistor on pin 4 is used to advantage to keep I0 and I1 at high logic levels while the alarm contact is open. With I2 at a low level and D0 at a high, this configures the circuit for 10 second recordings every hour. Note that all three resistors shown are for ESD protection, and aren't necessary for circuit operation. When the alarm contact closes, the three `I' inputs are all at a low level, causing recording to start and continue until the contact is released. Figure 3 is a programmable system using `DIP' type switches to allow the settings to be changed as needed. Power is from three AA size alkaline cells, which give approximately 4.8V when fresh. Strictly speaking the supply should be at 5V to be consistent with the Control L (LANC) system, but in practice, this works quite well. Three cell battery holders are available for this type of application, but if one can't be found, shorting out one position in a four cell holder will accomplish the same thing. Of course, a regulated 5V supply would be preferrable if one were available. Operation of either circuit is similar. The ELM303 circuitry is powered up before connecting it to the VDD = 4.5V VDD +
1
0.1F
1 2 3 4
8 7 6 5
120
4 2 1 5 3
120 +5V Control L mini DIN Cable Connector (male)
22K Alarm Contact
Figure 2. Alarm Triggering
camcorder, and the camcorder is powered and placed in the camera / standby state. The cable between the two is then connected and approximately one minute later, the camera will record one sequence, and will power down. After the duration set by the Interval pins, recording will be initiated again. Some cameras do not have power control inputs, so will require additional circuitry in order to take advantage of the power control capabilities. A toggle type circuit (driven from the power output pin) could be constructed for this purpose by the more adventurous experimenter, but is beyond the scope of this document to describe. Experimentation will determine the best settings to use for each of your applications. For plant growing experiments, try using the 60min / 1sec setting. You will find that 1 second is a little long for creating your own animations, but may be just right for others...
0.1F
8 7 6 5
120
4 5 3 1 2
33K
33K
33K
2 3 4
120 Control L mini DIN Cable Connector (male)
Period Set as per Table 1, closed = L and open = H
VDD 33K
Duration closed = 1 sec open = 10 sec
Figure 3. Time-Lapse Controller
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