Hello group,
I cannot understand of how the XCHG PRU instruction works (or cannot make it working as expected). I expect that "XCHG 10, r1, 4" should exchange the contents of r1 with the scratch pad bank0.r1, 4 bytes: put r1 contents there, and get S-pad data, simultaneously. However I see the XCHG behaviour exactly the same as the XIN instruction, that is scratchpad is being read OK, but nothing is written to the scratchpad. The code: mov r1, 0x01 XOUT 10, r1, 4 // init the S-pad to value of 0x01 mov r1, 0x02 XCHG 10, r1, 4 // Make S-pad=0x02, r1 = 0x01 SBCO r1, C24, 0x00, 4 // r1 -> RAM<0..3>, and I see the RAM0 = 0x01 - OK mov r1, 0x03 XCHG 10, r1, 4 // Make S-pad=0x03, r1 = 0x02 SBCO r1, C24, 0x04, 4 // r1 -> RAM<4..7>, but I see the RAM4 = 0x01 - BAD! Should be 0x02 Could somebody please confirm that XCHG instruction works, or does not work, or how to make it exchanging the data reg<->scratchpad? (no register shifting used: PRUCFG.SPP=0) Thanks! -- 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/d/optout.
