10.1. RPi 40-pin header programming

TI AM68A SK development board contain a 40 pin GPIO header, similar to the 40 pin header in the Raspberry Pi. These GPIOs can be controlled for digital input and output using the Python/CPP libraries provided in the TI GPIO Library packages. The libraries have the same API as the RPi.GPIO library for Raspberry Pi in order to provide an easy way to move applications running on the Raspberry Pi to the TI board.

TI GPIO Libraries are packaged under /opt directory. Run the below script to build and install the gpio libraries

/opt/edgeai-gst-apps# ./scripts/install_ti_gpio_libs.sh

By default, the 40-pin header is not enabled on AM69A SK board. This can be enabled by specifying the dtb overlay file k3-am68-sk-rpi-hdr-ehrpwm.dtbo in /run/media/BOOT-mmcblk1p1/uEnv.txt as given below.

name_overlays=k3-j721s2-edgeai-apps.dtbo k3-am68-sk-rpi-hdr-ehrpwm.dtbo

Reboot the board after editing and saving the file.

10.1.1. 40-pin header default configuration

The default pin configuration on the SK board is as follows. Any deviation from this needs modifications to the Linux DTBO. The table below lists pin numbers in all three supported modes, namely BOARD, BCM, and SOC.

BOARD: Physical Pin Number BCM : Broadcom SOC Numbering SOC : TI SOC Naming

../../../_images/am68sk_exp_hdr.png

BOARD

BCM

SOC

Function

3

2

GPIO0_4

I2C1 SDA

5

3

GPIO0_5

I2C1 SCL

7

4

WKUP_GPIO0_66

GPIO

8

14

GPIO0_1

GPIO

10

15

GPIO0_2

GPIO

11

17

GPIO0_42

GPIO

12

18

GPIO0_46

GPIO

13

27

GPIO0_36

GPIO

15

22

WKUP_GPIO0_49

GPIO

16

23

GPIO0_3

GPIO

18

24

GPIO0_13

GPIO

19

10

WKUP_GPIO0_1

GPIO

21

9

WKUP_GPIO0_2

GPIO

22

25

WKUP_GPIO0_67

GPIO

23

11

WKUP_GPIO0_0

GPIO

24

8

WKUP_GPIO0_3

GPIO

26

7

WKUP_GPIO0_15

GPIO

29

5

WKUP_GPIO0_56

GPIO

31

6

WKUP_GPIO0_57

GPIO

32

12

GPIO0_35

HW PWM

33

13

GPIO0_51

HW PWM

35

19

GPIO0_47

GPIO

36

16

GPIO0_41

HW PWM

37

26

GPIO0_27

GPIO

38

20

GPIO0_48

GPIO

40

21

GPIO0_45

GPIO

NOTE: Please refer to SK-AM68 User’s Guide for details on the expansion header pin names and functionality. Also refer to section 2.1.2 Power Budget Considerations for power/voltage limits on the expansion header pins.

10.1.2. Repositories

The Python and CPP projects are hosted on Texas Instruments GitHub. The links to the projects are given below. The details on installation and testing can be found in the respective project documentation.

Python Library: https://github.com/TexasInstruments/ti-gpio-py.git

CPP Library: https://github.com/TexasInstruments/ti-gpio-cpp.git

The above repositories are cloned and installed during the initialization process upon initial boot. The gpiozero library is also installed as a part fo the initialization.

10.1.3. Additional References

Please refer to the lik below for information on the 40-pin header numbering and naming conventions: