Jetson Identifying the GPIO Number

URL : https://docs.nvidia.com/jetson/archives/r35.1/DeveloperGuide/text/HR/JetsonModuleAdaptationAndBringUp/JetsonAgxOrinSeries.html#identifying-the-gpio-number

 

Identifying the GPIO Number

If you designed your own carrier board, to translate from SOM connector pins to actual GPIO numbers, you must understand the following GPIO mapping formula. The translated GPIO numbers can be controlled by the driver.

Because the Jetson module dynamically registers GPIOs, search the kernel messages to check the GPIO allocation ranges for each GPIO group. The command and resulting output are similar to the following:

root@jetson:/home/ubuntu# **dmesg** | **grep gpiochip**
[    5.726492] gpiochip0: registered GPIOs 348 to 511 on **tegra234-gpio**
[    5.732478] gpiochip1: registered GPIOs 316 to 347 on **tegra234-gpio-aon**
root@jetson:/home/ubuntu#

As shown in the output above, there are two Jetson GPIO ports with different base indices:

• tegra234-gpio, at base index 348
• tegra234-gpio-aon, at base index 316

You can check the GPIO number in one of the following ways:

• Using a calculation.

Before you get started, you need to know how you plan to configure the offset at each available port.

Here is the list of the tegra234 GPIO ports and offset mapping:

Port	Number of Pins	Port Offset
PORT_A	8	0
PORT_B	1	8
PORT_C	8	9
PORT_D	4	17
PORT_E	8	21
PORT_F	6	29
PORT_G	8	35
PORT_H	8	43
PORT_I	7	51
PORT_J	6	58
PORT_K	8	64
PORT_L	4	72
PORT_M	8	76
PORT_N	8	84
PORT_P	8	92
PORT_Q	8	100
PORT_R	6	108
PORT_X	8	114
PORT_Y	8	122
PORT_Z	8	130
PORT_AC	8	138
PORT_AD	4	146
PORT_AE	2	150
PORT_AF	4	152
PORT_AG	8	156
PORT_AA	8	0
PORT_BB	4	8
PORT_CC	8	12
PORT_DD	3	20
PORT_EE	8	23
PORT_GG	1	31

 

 

• Search for the pin details from the Orin pinmux table (see Pinmux Changes).
  For example SOC_GPIO08, which is GPIO3_PB.00.
• Identify the port as B and the Pin_offset as 0.
• Calculate the pin number with the following formula:
  base + port_offset + pin_offset
• Verify the following values:

• Using Kernel debugfs.

 

Note

To use a pin as GPIO, ensure that E_IO_HV field is disabled in corresponding pinmux register of the GPIO pin. You can disable the 3.3V Tolerance Enable field in the pinmux spreadsheet and reflash the board with the updated pinmux file.