External Triggers

Some of Prophesee products and sensors support external triggering (input or output signals) allowing to control the sensor and synchronize data between several devices.

Supported Trigger Functions

All Prophesee cameras allow to capture external Trigger In transitions along with the sensor native data stream.

Some Prophesee cameras (EVK1, EVK2 and EVK3 Gen31) can also provide an external Trigger Out signal with a programmable period and pulse.

Trigger In Principle

The following diagram depicts Trigger In signal detection and the corresponding sensor data flow insertion.

Trigger In principle diagram

A block circuitry is implemented to detect Trigger In signal transition on the sensor module.

When a complete transition cycle is occurring, a specific rising-edge event is generated first (shown as the dark blue box) followed by a specific falling edge event (shown as the red box).

The 2 events are occurring while the sensor is streaming its data (shown by light blue boxes). The 2 data flows are merged together and provided to the sensor output transmission interface.

Trigger In circuitry is able to detect up to 1 MHz clock transition. The minimum requirement for pulse width/period is 500/1000 ns. There is no limitation on pulse width duration and frequency.

This Trigger In function can be enabled/disabled using Metavision::I_TriggerIn::enable() method in Metavision HAL Metavision::I_TriggerIn facility.

Warning

Trigger In is disabled by default on camera start. So you need to call enable() to start detecting signal.

Trigger In can also capture the output signal of Trigger Out with a specific loopback mechanism. To configure the Trigger In facility, a channel parameter is used that depends on the camera. Here are the values to use for the Prophesee cameras:

Camera

Main channel

Loopback channel

EVK1 Gen3.x

0

6

EVK1 Gen4.x

1

6

EVK2 Gen4.1

1

3

EVK3 Gen3.1

0

6

EVK3 Gen4.1

1

3

Note

For other cameras, the list of available triggers and the available channels for Trigger In can be found in their datasheet.

Trigger Out Principle

Some Prophesee cameras (EVK1, EVK2 and EVK3 Gen31) also have the ability to provide an external Trigger Out signal for which the period and the pulse width is programmable.

Trigger Out principle diagram

Trigger Out functionality uses an internal time reference with 1us resolution, so that the maximum signal frequency is 0.5 MHz.

Both signal frequency and duty cycle can be adjusted by user using functions in Metavision HAL Metavision::I_TriggerOut class:

Trigger Out pulse width value shall be at least one time unit less than the pulse period. Otherwise, no Trigger Out pulse will be generated.

This function can be enabled and configured using the facility Metavision::I_TriggerOut of the HAL API.

Note

If you are interested in multi-cameras synchronization, contact us for more details. If you subscribed to a Professional license, you have access to our Knowledge Center with information about external connection interface for Prophesee Cameras and electrical specification for Trigger In and Out. In addition, you will find an application note about multi-cameras synchronization.