These tables are based on the BeagleBone Black System Reference Manual (Creative Commons) by Gerald Coley of BeagleBoard.org. They aren't really available anywhere else on the internet, so I thought I'd transcribe them into a more available format.
The PROC column is the pin number on the processor.
The PIN column is the pin number on the expansion header.
The MODE columns are the mode setting for each pin. Setting each mode to align with the mode column will give that function on that pin. Each pin's mode can be set individually.
Note that the MODE5 column is absent. That is not a typo. It just doesn't do anything. The only exception is GPIO0_7 in expansion header P9 has a mmc0_sdwp
* some pins are used by the internal storage (eMMC), and HDMI. 11-21 are used by eMMC. 27-46 are used by HDMI.
Using the "everything is a file" sys directory, you can use BASH or whatever to change the mode number for the pin in the NAME column.
echo 7 > /sys/kernel/debug/omap_mux/gpmc_ad4
echo 36 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio32/direction
echo 1 > /sys/class/gpio/gpio32/value
If you are using windows, TI has this GUI you can use called PinMuxTool / Pin Mux Utility. The BBB is AM335x r2 based.
The above only works if you're using the older kernel. The new 3.8 based kernel is missing this nifty pin mux feature. However, you can still check what they're muxed at even if you can't change them easily at runtime by looking at
/sys/kernel/debug/pinctrl/44e10800.pinmux/pingroups
root@arm:/sys/kernel/debug/pinctrl/44e10800.pinmux# cat pingroups
registered pin groups:
group: pinmux_userled_pins
pin 21 (44e10854)
pin 22 (44e10858)
pin 23 (44e1085c)
pin 24 (44e10860)
group: pinmux_rstctl_pins
pin 20 (44e10850)
group: pinmux_i2c0_pins
pin 98 (44e10988)
pin 99 (44e1098c)
group: pinmux_i2c2_pins
pin 94 (44e10978)
pin 95 (44e1097c)
group: pinmux_emmc2_pins
pin 32 (44e10880)
pin 33 (44e10884)pin 0 (44e10800)pin 1 (44e10804)pin 2 (44e10808)pin 3 (44e1080c)pin 4 (44e10810)pin 5 (44e10814)pin 6 (44e10818)pin 7 (44e1081c)group: pinmux_userled_pinspin 21 (44e10854)pin 22 (44e10858)pin 23 (44e1085c)pin 24 (44e10860)group: mcasp0_pinspin 107 (44e109ac)pin 103 (44e1099c)pin 101 (44e10994)pin 100 (44e10990)pin 106 (44e109a8)group: nxp_hdmi_bonelt_pinspin 108 (44e109b0)pin 40 (44e108a0)pin 41 (44e108a4)pin 42 (44e108a8)pin 43 (44e108ac)pin 44 (44e108b0)pin 45 (44e108b4)pin 46 (44e108b8)pin 47 (44e108bc)pin 48 (44e108c0)pin 49 (44e108c4)pin 50 (44e108c8)pin 51 (44e108cc)pin 52 (44e108d0)pin 53 (44e108d4)pin 54 (44e108d8)pin 55 (44e108dc)pin 56 (44e108e0)pin 57 (44e108e4)pin 58 (44e108e8)pin 59 (44e108ec)group: nxp_hdmi_bonelt_off_pinspin 108 (44e109b0)
root@beaglebone:~# cat /sys/kernel/debug/gpio GPIOs 0-31, gpio: GPIOs 32-63, gpio: gpio-52 (eMMC_RSTn ) out lo gpio-53 (beaglebone:green:usr) out lo gpio-54 (beaglebone:green:usr) out lo gpio-55 (beaglebone:green:usr) out hi gpio-56 (beaglebone:green:usr) out lo gpio-59 (McASP Clock Enable P) out hi GPIOs 64-95, gpio: GPIOs 96-127, gpio:
Be careful about this one, there are some much lower limits than you might be used to
▼ Expand
* VDD only works when the 5V barrel jack is used
It is recommended that you use I2C2 on pins 19 and 20 with the /dev/i2c-3 device.
To check which i2c interfaces are avaible, check
root@arm:~# ls -l /dev/i2c*
crw-rw---- 1 root i2c 89, 0 Jun 5 04:34 /dev/i2c-0 crw-rw---- 1 root i2c 89, 1 Jun 5 04:34 /dev/i2c-1
To see what addresses are being used, try the i2cdetect command. In the below example, I have a temperature sensor hooked up to pins 19 and 20 that is using 48. Also note that the UU addresses are being used by the system and are unavailable.
root@beaglebone:~# i2cdetect -y -r 3 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- 48 -- -- -- -- -- -- -- 50: -- -- -- -- UU UU UU UU -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --