Point Grey Flea3 USB 3.0 Technical Reference 6 Image Acquisition
Configure a Different GPIO Pin to be an External Trigger
If you wish to use a different GPIO pin as the external trigger instead of the default trigger, you will need to configure
the specific pin to be an input trigger, then configure the camera to use this newly allocated trigger pin.
For example, to configure the camera to use GPIO2 as the external trigger pin:
1. Get the value of the PIO_DIRECTION register 0x11F8 (page 91) to determine the current states of each GPIO
pin. For example:
2 0 0 0 0 0 0 0 Hex
0010 0000 0000 0000 0000 0000 0000 0000 Binary
0-7 8-15 16-23 24-31 Bits
0x11F8 = 0x20000000
Each of the first four bits represents the current state of its associated GPIO pin: ‘0’ indicates it is a input/trigger, and
‘1’ indicates it is an output/strobe. In the example above, 0x2 = 0010 in binary, so GPIO0, GPIO1 and GPIO 3 are all
configured as inputs and GPIO2 is an output.
2. To set GPIO2 in the example above to be an input/trigger, and all other GPIO pins as outputs:
D 0 0 0 0 0 0 0 Hex
1101 0000 0000 0000 0000 0000 0000 0000 Binary
0-7 8-15 16-23 24-31 Bits
0x11F8 = 0xD0000000
3. Configure the camera to use GPIO2 as the external trigger source by setting bits 8-10 of the TRIGGER_MODE
register (page 90). For example, for GPIO pin “2”, we set bits 8-10 to 010, which is 2 in binary):
8 0 4 0 0 0 0 0 Hex
1000 0000 0100 0000 0000 0000 0000 0000 Binary
0-7 8-15 16-23 24-31 Bits
0x830 = 0x8040000000 (assumes bits
11-31 are zero)
Enable Trigger Mode
The camera must be put into Trigger Mode 0 to allow it to be externally triggered.
To do this in the FlyCap graphical user interface:
1. Open the Camera Control Dialog
2. Select the “Trigger” tab
3. Check the "Enable/disable trigger" (“Trigger On/Off” in earlier versions) checkbox
To do this by directly accessing the camera’s TRIGGER_MODE register (page 90):
1. Get register 0x830
2. Turn trigger Mode 0 ON by setting bit 6 to one (1) and setting bits 12-15 to zero (0)
Revised 9/27/2012
Copyright ©2011-2012 Point Grey Research Inc.
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