GPIOs on DIMM-AM335 under Linux

Enabling GPIO control

To get access to an GPIO pin, first, write the GPIO number to /sys/class/gpio/export

echo 7 > /sys/class/gpio/export

Now you should find a directory in /sys/class/gpio to access your GPIO pin. Write in or out to direction to change the direction of the pin:

echo out > /sys/class/gpio/gpio7/direction

The value (0 for off, 1 for on) of the pin is in the value file. To read or change it, read the file or write to it.

echo 1 > /sys/class/gpio/gpio7/valuecat /sys/class/gpio/gpio7/value

The list of GPIO numbers can be found below.

The two color led can be controlled by two GPIO pins.

Color	Bank and pin	GPIO Number	Notes
Green	2-4	68	output is inverted, 0 is on
Red	2-5	69

There are 8 GPIOs on J12 with a signal level of 3.3V and 14 more on J16 using the GPIO expander.

Connector	Pin	Signal	Bank and pin	GPIO Number
J12	4	GPIO_0	0-7	7
J12	8	GPIO_2	1-21	53
J12	12	GPIO_4	2-19	83
J12	14	GPIO_5	3-9	105
J12	16	GPIO_6	2-18	82
J12	18	GPIO_7	3-10	106
J12	20	GPIO_8	0-13	13
J12	22	GPIO_9	0-12	12
J16	3	GPIO_I2C_0		128
J16	4	GPIO_I2C_8		136
J16	5	GPIO_I2C_1		129
J16	6	GPIO_I2C_9		137
J16	7	GPIO_I2C_2		130
J16	8	GPIO_I2C_10		138
J16	9	GPIO_I2C_3		131
J16	10	GPIO_I2C_11		139
J16	11	GPIO_I2C_4		132
J16	12	GPIO_I2C_12		140
J16	13	GPIO_I2C_5		133
J16	14	GPIO_I2C_13		141
J16	15	GPIO_I2C_6		134
J16	17	GPIO_I2C_7		135

The Lothron 3 has 8 accessible GPIO pins on J25.

Connector	Pin	Signal	Bank and pin	GPIO Number
J25	11	GPIO_0	0-7	7
J25	13	GPIO_2	1-21	53
J25	15	GPIO_4	2-19	83
J25	16	GPIO_5	3-9	105
J25	17	GPIO_6	2-18	82
J25	18	GPIO_7	3-10	106
J25	19	GPIO_8	0-13	13
J25	20	GPIO_9	0-12	12