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GPIO / Trigger / Strobe Interface
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Optocoupler interface / Strobe Interface
Optically isolated inputs and outputs.
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Optocoupler basics
  Diagram of basic optocoupler function | An optocoupler is a device using optical path to transfer an electronic signal between two circuits. It basically consists of a photodiode between pin 1 and 2 converting the input signal to light and a phototransistor converting the light again to electronic signal at pin 3 and 4. The optocoupler is useful in situations where one part of the circuit needs to be galvanically isolated from the other part to prevent damage or unwanted interference. It is used to prevent ground loops or to block voltage spikes. For effective use of the optocoupler it is important to control it using an independent power supply. When the external circuit is galvanically connected to the camera (eg. when reusing the camera's power to control the optocoupler), the optocoupler's protective function is eliminated. |
Due to the schematic characteristic the signal transmitted through an optocoupler interface will be inverted. For details please see schematic below.
Optocoupler parameters summary
Parameter | Input Value | Output Value | |
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Operating voltage | 3.3 5 - 30 24 V3.3 | 5 - 30 24 V | |
Input current | 7.5 mA | < 100mA | |
External resistor requirement | No | Yes, output current must be limited to 100 mA | |
ON voltage level | > 4.5 V | ||
OFF voltage level | < 1.5 V | ||
OFF to ON delay | < 125 ns | 750 ns | |
OFF to ON rise time (10 to 90%) | 1.0-4.0 µs | ||
ON to OFF delay | < 125 ns | 2.4 – 25 µs | |
ON to OFF fall time (90 to 10%) | 9.0 – 140 µs | ||
OFF to ON jitter | ± 5 ns | ± 20 ns | |
ON to OFF jitter | ± 5 ns | ± 0.1 µs | |
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Optocoupler inputs
iam TheCORSIGHTcamerais equipped with four optically isolated input lines. One input optocoupler is fully independent, the other three are connected with a common cathode (Section “I/O connector”) due to limited number of pins on the I/O connector. Each input line is protected by a current limiter circuit.
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The optocoupler input's logical state is understood as logical 1 0 if no current is flowing through the optocoupler diode, logical 0 1 if current is flowing through the diode. See schematic below. |
The optocoupler is guaranteed to be switched on (logical 0 input 1 status) when the voltage applied to the input is in range of 3.3 5 - 30V 24V (tolerance 10%). It is guaranteed to be switched off (logical 1 input 0 status) when the applied voltage is under 21.0V5V. The input status is undefined between 2V and 3V1.5V and 4.5V, the input voltage must not exceed the 30V 24V limit!
The input lines are using fast optocouplers: The propagation time is under 125 ns, for both rising and falling signal edge (assuming input signal with strongly steep edge). The exact switching speed may vary with temperature and the used input voltage level - the listed specifications are the worst case values.
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The optocoupler inputs have no protection against wrong polarity. Be sure to connect them always with correct polarity according to the documented wiring diagrams and connector pinouts. |
The nominal input current is 7.5 mA — the input signal must be able to deliver at least this amount of current.
The optocoupler inputs are TTL compatible provided that the signal source is capable of supplying the input current of 7.5 mA.
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The optocoupler input lines are equipped with a debouncer to prevent generating unwanted input signals. |
Trigger input
Any of the available optocoupler inputs can be used for triggering. The input line mapping on the camera connectors is described in section Connector and cable description .
Schematic
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If the camera serial number has an X or Y in the 9th digit (e.g. 14A2GEBAX2042013) the I/O connector has the Prototype pinout. Expand below! |
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The schematic of newer cameras I/O interface can be found below. |
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Optocoupler outputs
iam is equipped with three The input lines are using fast optocouplers: The propagation time is under 125 ns, for both rising and falling signal edge (assuming input signal with strongly steep edge). The exact switching speed may vary with temperature and the used input voltage level - the listed specifications are the worst case values.
Optocoupler outputs
TheCORSIGHT camera is equipped with four optically isolated output lines. One output optocoupler is fully independent, the other two three are connected with a common collector (Section “I/O connector”) due to limited number of pins on the I/O connector.
After power up, the optocoupler outputs are in high impedance state and they remain in that state until reconfigured from the software interface. Automatic reconfiguration at start up can be done by means of user setsWhenever the optocoupler output is disconnected in the SW interface, it gets in high impedance status.
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The optocoupler output's logical state is understood as logical 0 when its output transistor is in high impedance, logical 1 if it is in low impedance mode. See schematic below |
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The optocoupler output work with operating voltage range of 5-24 V. The maximal switched output current is 100 mA per optocoupler, higher current could damage the optocoupler output circuit. |
The rising edge (switching to logical 1) propagation time is 750 ns, the falling edge propagation time is under 25 µs. The exact switching speed may vary with temperature and the used input voltage level — the listed specifications are the worst case values.
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The optocoupler output work with operating voltage range of 3.3-30 V. The maximal switched output current is 100 mA per optocoupler, higher current could damage the optocoupler output circuit. |
Strobe output
Any of the available optocoupler output can be used for strobe control. The output line mapping on the camera connectors is described in section Connector and cable description .
Schematic
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If the camera serial number has an X or Y in the 9th digit (e.g. 14A2GEBAX2042013) the I/O connector has the Prototype pinout. Expand below! |
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| title | Expand if the camera serial number has an X or Y in the 9th digit (e.g. 14A2GEBAX2042013) |
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The schematic of newer cameras I/O interface can be found below. |
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TTL I/O's
Standard 5V TTL (transistor-transistor logic) interface.
After power up, the TTL outputs are driven low — and they remain driven low until reconfigured from the software interface. Whenever the TTL output is disconnected in the SW interface, it gets in driven low status. TTL inputs are pulled up to 5V inside the camera to guarantee a stable input in case nothing is connected. To generate a steep edge the TTL input driver should be capable of driving and sinking 10mA.
The TTL input's and output's logical state is understood as logical 1 when it's driven high (5V) and logical 0 when it's not driven (0V).
The TTL input lines are equipped with a debouncer to prevent generating unwanted input signals.
The delays listed in the table are setup dependent mean values, while the jitters are maximal deviations (± ) from those mean values.
TTL input/output parameters summary
Parameter | Value |
Operating voltage ON voltage level | 5V±10% (absolute maximum 6.5V) > 3.5 V |
OFF voltage level | < 1.5 V |
High level output current | -32mA max / high level at 3.8V min |
Low level output current | 32mA max / low level at 0.55V max |
Input to sensor trigger delay | 19 µs (jitter +13/-2 µs) |
TTL-in to TTL-out delay | 32 µs (jitter +10/-2 µs) |
Serial port interface
Standard RS232 communication interface, accessible directly from the camera's feature tree.
Configurable communication parameters are: baud rate, parity, data bits, stop bits.
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