Linux/AM3354: Access to clocks/timers in PRU assembly programs

Jonas Hjulstad

Part Number: AM3354

Tool/software: Linux

Hi!

I've been following basic examples for SPI-communication using Derek Molloy's PRU example:

One PRU is used as an adjustable clock for the communication here, but i was wondering if it is possible to access and use system clocks. (I have a purpose for the other PRU).

This is on the BeagleBone Black, where there are mcSPI-modules available. The purpose is however to demonstrate usage of PRU and its communication with the main processor.

over 7 years ago

0 Nick Saulnier over 7 years ago

TI__Guru** 110030 points

Hello Jonas,

What version of Linux are you using?

I am not sure I understand what you are asking. Could you restate what you are trying to accomplish?

As an FYI, there is also a TI design for interfacing with multiple ADCs by implementing SPI on the PRU here: www.ti.com/.../TIDA-01555

Regards,
Nick

0 Jonas Hjulstad over 7 years ago in reply to Nick Saulnier

Prodigy 160 points

What is the best way to use other clocks/timers to keep track of time in a PRU-assembler program?

0 Nick Saulnier over 7 years ago in reply to Jonas Hjulstad

TI__Guru** 110030 points

Hello Jonas,

The PRU-ICSS has two methods of keeping track of time: The Industrial Ethernet Peripheral timer (sometimes called IEP timer, sometimes called Industrial Ethernet Timer in the AM335x technical reference manual or TRM), and the cycle count register. The IEP timer is probably what you are looking for.

Regards,
Nick

0 Nick Saulnier over 7 years ago in reply to Nick Saulnier

TI__Guru** 110030 points

We do not have an assembly example of using the IEP timer, but we have a C example within the PRU Software support package (in your Linux Processor SDK under example-applications/pru-icss-x.x.x/examples/am335x/PRU_IEP, or at the git repo git.ti.com/.../ ).

General TI PRU resources are at processors.wiki.ti.com/.../PRU-ICSS

Regards,
Nick

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Linux/AM3354: Access to clocks/timers in PRU assembly programs