Pin Mux

To do pin muxing, look at the pin names and modes in the BeagleBone reference manual:
 
Then, locate the pin you want to map. Find the name. Find the mode you want to set.
 
The name is the name that you find in the table for mode 0 in the reference manual.

In this example, we want to set mode to 6 for pin 14 on connector P9 (named gpmc_a2) to get the signal we want (ehrpwm1A_mux1) out :
  • echo 6 > /sys/kernel/debug/omap_mux/gpmc_a2

The value that is written is a combination of both the mode number and some flags:
  • Bit 5: 1 - Input, 0 - Output
  • Bit 4: 1 - Pull up, 0 - Pull down
  • Bit 3: 1 - Pull disabled, 0 - Pull enabled
  • Bit 2 \
  • Bit 1 |- Mode
  • Bit 0 /
From just a quick test, it seems the pull-up resistor is about 34kOhm in size.

 
 
The gadget spec URL could not be found
Comments