[arm-allstar] txmixb Enable

[rt707]

Could someone possibly tell me how to "turn on" txmixb or the right channel
in simpleusb? I am using a Motorola m-1225LS for a RF link to my repeater
with a RIM-Maxtrac and would like to feed TX audio in via pin 5 of the
radio's accessory connector for "flat audio" going out. On the RIM-Maxtrac
schematic, pin 5 is connected to txmixb or the right audio channel. Thanks
for any help you can provide.
Dan
KE7NLT