Linux/AM4378: Motion control in PRU

sr su

Part Number: AM4378

Tool/software: Linux

Hi sir,

I am running a real time control project using processor AM4378. In this project a minimum latency is required, and it is possible to implement the control function in the PRU as described in spry246b .

There are few questions as follows :

1. How much memory size can be used to implement the control algorithm ? Is there any limitation except for the RAM size ?

2. The control algrithm may use some math functions like sin /cos/ tan/... etc, and some types of variables such as float, double,... Is it okay to do it in PRU ?

3. Can ETHERCAT master be executed in PRU for the same reason of a minimun latency?

Best regards,

richard

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

I cannot find the document you refer as "spry246b". There is a TI document www.ti.com/.../spry246.pdf which discusses video codecs. Can you please post the link to the document you refer?

0 sr su over 7 years ago in reply to Biser Gatchev-XID

Prodigy 140 points

Here is the link:

www.ti.com/.../spry264b.pdf

0 Biser Gatchev-XID over 7 years ago in reply to sr su

TI__Guru**** 393215 points

Thanks, I have asked the PRU experts to comment.

0 melissaw over 7 years ago in reply to Biser Gatchev-XID

TI__Genius 15990 points

Hi Richard,

If you use Linux’s RemoteProc & RPMsg drivers to load the PRU firmware, then you’ll need to reserve at least 1K of the IRAM for the RemoteProc & RPMsg framework. Below are a few links about this framework:
The PRU hardware is not optimized for math functions, especially floats and doubles. As such, performing these type of operations on the PRU are expensive in terms of code size, PRU cycles, and power. Our general advice is to run these type of operations on the A9 core.
Ethercat slave is available on the AM437x PRU-ICSS. However, Ethercat master is only available on the AM437x CPSW. Additional details about this Ethercat master solution are available at https://www.acontis.com/en/ethercat-for-ti-processors.html.

Regards,

Melissa

Processors

Processors forum

Linux/AM4378: Motion control in PRU