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Pins 16 and 18 are actually SD3_CMD and SD3_CLK signals that can be muxed to support flex can TX/RX interface (i.e. those can be connected to an external CAN).
(*) SPI and I2C & UART can also be muxed to be GPIO
Serial UART port access
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The UART port for debug can be accessed on the 26 pin header as follows –
Pin 6/9/14/20/25 GND
Pin 1 3.3V
Pin 8 buffered i.MX6 UART TX – pulled up to 3.3v
Pin 10 buffered i.MX6 UART RX – pulled up to 3.3v
Notice that the pin number starts as pin #1 on the edge of the board, towards the micro-USB connector; then number #2 is the one towards the corner of the board.
Accessing GPIO from Linux user space
General
Please have a look at WiringX, which also supports the Hummingboard:
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The external GPIOs are available under the /sys/class/gpio folder in Linux.
To control on the GPIO pins you need to calculate the GPIO number XX (*) and run the commands below:
Get the current list of reserved GPIO
| Code Block |
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> mount -t debugfs none /sys/kernel/debug > cat /sys/kernel/debug/gpio |
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You can take the GPIO Number from the above table (*)
Serial UART port access
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The UART port for debug can be accessed on the 26 pin header as follows –
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External Links and References
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