Beaglebone Black ADC with 11-BETAs?

Brian McGovern (bmcgover) bmcgover at cisco.com
Wed Aug 3 20:52:45 UTC 2016


Its been 6+ months since I've worked with a BBB and the analog inputs. "Back in the day", I used the interface as described by ti_adc(4) man page. However, the last couple of days, I've built up an image using the code that is on the 11.0 release path. The problem I'm seeing is that the ADC controller appear to be disabled in this builds...

root at beaglebone:~ # dmesg | grep adc
ti_adc0: <TI ADC controller> mem 0x44e0d000-0x44e0dfff disabled on simplebus0
ti_adc0: scheme: 0x1 func: 0x730 rtl: 0 rev: 0.1 custom rev: 0


... and the sysctl interface seems to be similarly truncated....

root at beaglebone:~ # sysctl -a | grep adc
dev.ti_adc.0.clockdiv: 2400
dev.ti_adc.0.%parent: simplebus0
dev.ti_adc.0.%pnpinfo: name=tscadc at 44e0d000 compat=ti,am3359-tscadc
dev.ti_adc.0.%location: 
dev.ti_adc.0.%driver: ti_adc
dev.ti_adc.0.%desc: TI ADC controller
dev.ti_adc.%parent: 

I noticed in the /boot/msdos/bboneblk.dts file that tscadc at 44e0d000 had a status = "disabled". I changed it to "okay" per other nodes, recompiled it to bboneblk.dtb via dtc, rebooted, and still no joy.

Is the boot process using these files, or is the device tree built in to the kernel (meaning I have to make fixes elsewhere and re-run the build)?


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