You are right! I can read any pin with a simply:
LSR r3, r31.b0, 3 //shift and mask
AND r3, r3, 0x01
How can I increment a register eg. r4 bit by bit with the last state of
r3 ? what I need is add bits to register.
I tried with SET but without luck.
On 06/23/2014 11:57 AM, [email protected] wrote:
----Ursprungligt meddelande----
Från: [email protected]
Datum: 2014-06-23 14:04
Till: <[email protected]>
Kopia: <[email protected]>
Ärende: Re: [beagleboard] Re: BBB PRU input test
On 6/23/2014 6:52 AM, TJF wrote:
Am Montag, 23. Juni 2014 06:19:52 UTC+2 schrieb [email protected]:
why "set r3, r31.t16" results in r3=0x08 ?
I'd like the pru asm compiler just reject this code as it seems of
little
sense.
Yes, I agree. pasm should output the same error message as for
MOV r3, r31.t16
which is
???.p(?) Error: Operand 2 use of .T field not allowed here
There is no error from pasm because this is a valid form of the SET
command (Format 3, Source Abbreviated).
The problem here is that you are reading from R31 using the SET
command,
which the PRU reference guide explicitly states does not work. The
reference guide indicates the source will be NULL, which one might
*assume* means all zeros, but in reality could mean just about anything
(including something like "the source input pins on the ALU are
floating").
So if you *REALLY* want to know, go ask TI if they'll share details
about what happens when using R31 as a source for the SET/CLR
operations, but I don't think you'll get very far.
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