Thanks for the reply. I'm a big fan of LinuxCNC btw (use it on a couple of 
mills at my makerspace), so I think that's a very cool project.

I should have stated in my post that I did get a newer version of pasm 
(pasm_2 I think it is) and until then the XOUT was creating an assembler 
error when it hit the opcode.

I see in your code you're using scratch pad 0 (the 10 in your 
instructions). I'm trying to use the direct PRU to PRU version (14) and 
it's not working for me. I just tried your approach (pad 0, AKA 10) and it 
works fine.

Am I wrong in thinking you could use 14 and copy registers directly between 
the PRU's?

-Kent

On Wednesday, October 9, 2013 9:08:48 PM UTC-5, Charles Steinkuehler wrote:
>
> On 10/9/2013 3:58 PM, Kent Bowling wrote: 
> > I'm currently trying to us the scratch pad to do some PRU0<-->PRU1 
> > communication. I cannot get it working and I'm worried I'm missing some 
> > crucial initialization step of some sort. I've got other things working 
> > (including interrupts being sent between the two PRU's), but I can't get 
> > XOUT (or XIN) to work. 
> > 
> > Are there any examples or source code I can look at out there doing this 
> > successfully. 
>
> Those instructions work fine for me.  I've got a working example in my 
> PRU code for LinuxCNC.  I use the xout instruction to store the GPIO 
> addresses (which are only used once per task loop but take up four 
> registers) as part of system setup, the read them in a single 
> instruction cycle using xin. 
>
> Xout example: 
>
> https://github.com/cdsteinkuehler/linuxcnc/blob/MachineKit-ubc/src/hal/drivers/hal_pru_generic/pru_generic.p#L201
>  
>
> Xin example: 
>
> https://github.com/cdsteinkuehler/linuxcnc/blob/MachineKit-ubc/src/hal/drivers/hal_pru_generic/pru_wait.p#L69
>  
>
> Using the single-stepping debugger available with LinuxCNC, you can see 
> the instruction working properly. 
>
> NOTE:  You do need to make sure you're using a version of pasm that 
> supports these instructions.  The first version from TI didn't. 
>
> -- 
> Charles Steinkuehler 
> [email protected] <javascript:> 
>

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