Snapshot lightness change if trigger frequence change on MT9V034

OpenMV Products
1

I don’t understand why if triggered mode on MT9V034 is activated, the lightness of the image change despite a fixed exposure set.

import sensor, image, time
from pyb import Pin, ExtInt

roi = (196 , 82 , 229 , 152) #VGA f2.8
sensor.reset()
sensor.set_pixformat(sensor.GRAYSCALE)
sensor.set_framesize(sensor.VGA)
sensor.set_auto_gain(False)
sensor.set_auto_exposure(False, exposure_us=100)
sensor.set_windowing(roi)
if (sensor.get_id() ==  sensor.MT9V034):
    sensor.ioctl(sensor.IOCTL_SET_TRIGGERED_MODE, True)
sensor.skip_frames(time = 1000)
clock = time.clock()

i = 0
lasttriggertime = time.ticks_us()
cap = 0

def callback (line):
    global cap
    cap = 1

ext = ExtInt(Pin('P9'), ExtInt.IRQ_RISING, Pin.PULL_DOWN, callback)

while(True):
    if (cap == 1):
        clock.tick()
        triggertime = time.ticks_us()
        img = sensor.snapshot()
        aftersnapshottime = time.ticks_us()
        print( "snapshot " + str(i) + \
            " Cycle(ms) " + str(round(time.ticks_diff(triggertime,lasttriggertime)/1000,1)) + \
            " Snapshot(ms) " + str(round(time.ticks_diff(aftersnapshottime,triggertime)/1000,1)) + \
            " FPS " + str(round(clock.fps(),1)) )
        i = i + 1
        lasttriggertime = triggertime
        cap = 0

I tried as suggested here(IOCTL_SET_TRIGGERED_MODE problem - OpenMV Products - OpenMV Forums) to play with sensor.__read_reg() to understand whats happen. But I’m far to understand the concept of integration time of the datasheet.

Snapshots attached:
with-trigger-02Hz.png
without-trigger.png
with-trigger-05Hz.png
with-trigger-10Hz.png
with-trigger-50Hz.png

2

It shouldn’t matter.

Mmm, the regs being touched by triggered mode have nothing to do with the integration time ones.

Make a bug ticket on GitHub and I’ll take a look.