Precise Hardware Triggering - Latency Time

Autonomous Machines Jetson & Embedded Systems Jetson AGX Xavier
1

I have a sensor that produces a high signal on detecting a corrugated board. The output signal of the sensor is connected as an input to the NVIDIA Xavier GPIO unit. I read the signal in the code and start the capture request using Argus. My camera does not have an external hardware trigger for capturing. My questions are,

  1. Is there a way to do precise triggering for capturing images from the cameras. I’m expecting a latency of less than 60 microseconds.

  2. Are there any external FPGA boards to do these kind of precise triggering?

  3. What is the maximum latency time that I can expect for the aforementioned process in Xavier? (Sensor - GPIO - Capture Request (Argus))

2

hello sathish.nitt76,

you’ll also need to consider the sensor frame-rate, suppose you’re working with a 30-fps sensor. you should expect there’s 33ms to issue a capture request.
besides, please also note that, there’s ring buffers to queue captured frames,
please also refer to below kernel source, it’ll release buffer N at N+2 frame start event.
for example,

<i>$l4t-r32.3.1/JAX_TX2/Linux_for_Tegra/source/public/kernel_src/kernel/nvidia/drivers/media/platform/tegra/camera/vi/channel.c</i>

void tegra_channel_ring_buffer(struct tegra_channel *chan,
					struct vb2_v4l2_buffer *vb,
					struct timespec *ts, int state)

{
...
	/* release buffer N at N+2 frame start event */
	if (chan->num_buffers >= (chan->capture_queue_depth - 1))
		free_ring_buffers(chan, 1);

please also contact with Jetson Preferred Partners for camera solutions,
thanks