Hi John, Is there a way to enable ADC without using device tree? I couldn't find a way to do it in the reference manual. Thank you.
Regards, Nhan On Sunday, February 23, 2014 3:05:39 AM UTC+1, john3909 wrote: > > > > From: Nhan Nguyen <chinh...@gmail.com <javascript:>> > Reply-To: <beagl...@googlegroups.com <javascript:>> > Date: Saturday, February 22, 2014 at 5:40 PM > To: <beagl...@googlegroups.com <javascript:>> > Subject: Re: [beagleboard] PRUSS and accessing ADC registers on > Beaglebone Black > > Hi Charles, > > Thank you very much for your answer. I manage to access it after enable > ADC using 'echo BB-ADC > /sys/devices/bone.capemgr.*/slots' . Though I > could only do it in kernel 3.8, later kernel (3.12) gives an error saying > symbol ocp could not be found. I do not really know how to change the .dts > to get it working . Anyhow, I will work with 3.8 for now. > > There is no cape manager in V3.12 > > Regards, > John > > > Sincere, > Nhan Nguyen > > On Wednesday, February 19, 2014 2:57:31 PM UTC+1, Charles Steinkuehler > wrote: >> >> On 2/19/2014 7:43 AM, Nhan Nguyen wrote: >> > Hi everyone, >> > >> > I have been trying to use PRU to read multiple ADC inputs. Unfornately, >> I >> > am stuck at accessing to the ADC registers (chapter 12 on AM335x >> technical >> > reference manual). I set the OCP registers, checked the PMAO registers >> on >> > PRU to ensure access to external host. For example, I read the ADC >> REVISION >> > as below: (tried to write to STEPCONFIG and STEPENABLE, etc.) >> > >> > MOV r13, 0x44E0D000 //ADC REVISION >> > LBBO r5, r13, 0, 4 >> > SBCO r5, C28, 4, 4 //store REVISION to shared memory to show with C >> > program >> > >> > .. but everything returns 0. >> > >> > I install Ubuntu 13.04 on Beaglebone Black, tried kernels 3.8, 3.12. >> PRU >> > worked with shared memory accessing, and GPIO1 registers (I am not sure >> > what to try next) . I haven't tried it on the official Angstrom image, >> > because I still couldn't get PRU to work right away on it. >> >> I suggest you remove the PRU from the setup temporarily and try directly >> reading the memory from C. This will be a lot easier to debug, and the >> PRU has no chance of reading ADC values if you can't read them from the >> ARM. >> >> As a guess, I suspect you don't have the ADC hardware setup properly and >> are getting bus faults when reading. This will show up as an error if >> you try to read the memory location from the ARM (making it easier to >> debug). Make sure you have loaded a device tree overlay that enables >> the TSC hardware (Touch Screen Controller = ADC) and populates an >> appropriate state-machine instruction table to digitize the values you >> are interested in. Unlike simpler microcontrollers, each major >> subsystem in the AM335x can be powered up or shut down, and by default >> most systems (ADC, PWM, etc) are powered down with their clocks disabled >> until you explicitly enable them. >> >> Once you can properly read the values from a raw memory location using >> the ARM, the PRU should be able to read them as well. >> >> -- >> Charles Steinkuehler >> cha...@steinkuehler.net >> > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard...@googlegroups.com <javascript:>. > For more options, visit https://groups.google.com/groups/opt_out. > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
