GPIOs on DIMM-MX53 under Linux

Enabeling GPIO control

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

echo 40 > /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/gpio40/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/gpio40/valuecat /sys/class/gpio/gpio40/value

The list of GPIO numbers can be found below.

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

Connector	Pin	Signal	Signal on MX53	Bank and pin	GPIO Number
J12	4	GPIO_0	GPIO_A	2-8	40
J12	6	GPIO_1	GPIO_B	2-9	41
J12	8	GPIO_2	GPIO_C	2-10	42
J12	10	GPIO_3	GPIO_D	2-11	43
J12	12	GPIO_4	GPIO_E	2-12	44
J12	14	GPIO_5	GPIO_F	2-13	45
J12	16	GPIO_6	GPIO_G	2-14	46
J12	18	GPIO_7	GPIO_H	2-15	47
J16	3	GPIO_I2C_0			224
J16	4	GPIO_I2C_8			232
J16	5	GPIO_I2C_1			225
J16	6	GPIO_I2C_9			233
J16	7	GPIO_I2C_2			226
J16	8	GPIO_I2C_10			234
J16	9	GPIO_I2C_3			227
J16	10	GPIO_I2C_11			235
J16	11	GPIO_I2C_4			228
J16	12	GPIO_I2C_12			236
J16	13	GPIO_I2C_5			229
J16	14	GPIO_I2C_13			237
J16	15	GPIO_I2C_6			230
J16	17	GPIO_I2C_7			231

The Lothron 3 has 8 accessible GPIO pins on J25.

Connector	Pin	Signal	Signal on MX53	Bank and pin	GPIO Number
J25	11	GPIO_0	GPIO_A	2-8	40
J25	12	GPIO_1	GPIO_B	2-9	41
J25	13	GPIO_2	GPIO_C	2-10	42
J25	14	GPIO_3	GPIO_D	2-11	43
J25	15	GPIO_4	GPIO_E	2-12	44
J25	16	GPIO_5	GPIO_F	2-13	45
J25	17	GPIO_6	GPIO_G	2-14	46
J25	18	GPIO_7	GPIO_H	2-15	47