Shift register PRU

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1

Hi folks,

i’m currently working with the PRU of the beagle bone black to read and decode a SSI Protocol.
Therefore I want to use the build in 28 bit shift register of the PRU. I found out, that the shift register is configured via the GPCFG0 (pru0) register.
Can anyone explain to me, how I can use the shift register?
I also haven’t found the basic-adress of register GPCFG0, just the offset with 0x08.

With best regards
Christian

2

Hi folks,

i'm currently working with the PRU of the beagle bone black to read and
decode a SSI Protocol.
Therefore I want to use the build in 28 bit shift register of the PRU. I
found out, that the shift register is configured via the GPCFG0 (pru0)
register.
Can anyone explain to me, how I can use the shift register?

I am not aware of anyone in the BeagleBone community who has used the
shift register for an application, so I don't know of any example
code. You will have to refer to the PRU Reference Guide for usage
details.

Note that it doesn't look like you can use an external clock for the
28-bit shift register, so hopefully your data rate is stable and maps
nicely to the available clock frequencies.

I also haven't found the basic-adress of register GPCFG0, just the offset
with 0x08.

In section 3.1.2 "Local Data Memory Map", it shows the base address of
the CFG block is 0x0002_6000.

3

Thanks a lot. I think I missed the part with the Local Data Memory Map.
I’ll try it out and post the code when it works as expected.

Christian