AM2431: Help Using PRU for Data Encoding

Keito Katafuchi

Part Number: AM2431

I am trying to understand how to encode data with the PRU.
As an example, if you wanted to perform NRZ encoding on some data-stream sent out with the GPO Shift Out feature, you could add some external logic.
This logic might toggle the output state if the input was "1", or keep the output the same if the input was a "0".

This is usually done with external logic, or an FPGA if the project scale demands it.
I noticed the C2000 microcontrollers include "CLB" allowing custom logic block configurations...

1) Does the AM243x have some way to apply custom logic to inputs/outputs?

2) Could you recommend a way to achieve NRZ encoding on AM243x? (Some arbitrary data stored in DRAM0 is encoded, and pulled into R30/SH0/SH to be shifted out via GPO Shift Out feature)

over 2 years ago

+1 Dhaval Khandla over 2 years ago

TI__Mastermind 28384 points

Keito Katafuchi said:
1) Does the AM243x have some way to apply custom logic to inputs/outputs?

As you mentioned, PRU-ICSSG peripheral is an option for implementing custom IO logic. You can refer to https://software-dl.ti.com/processor-industrial-sw/esd/motor_control_sdk/am243x/09_00_00_05/mcu_plus_sdk/docs/api_guide_am243x/COMPONENT_PRU_GUIDE_INTRO.html from SDK docs and section 6.4 Programmable Real-Time Unit and Industrial Communication Subsystem - Gigabit (PRU_ICSSG) in https://www.ti.com/lit/ug/spruim2h/spruim2h.pdf?ts=1700634782033&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FAM2434 for more details.

Keito Katafuchi said:
2) Could you recommend a way to achieve NRZ encoding on AM243x? (Some arbitrary data stored in DRAM0 is encoded, and pulled into R30/SH0/SH to be shifted out via GPO Shift Out feature)

GPIO mode is one option. You can write a firmware keep writing data into R30 directly based on your timing requirements without using shift mode. Shift mode can also be used.

You can refer to following example from AM263x MCU SDK (same example can run on AM243x as well) which uses GPIO mode for generating a SENT protocol signal : https://software-dl.ti.com/mcu-plus-sdk/esd/AM263X/09_00_00_35/exports/docs/api_guide_am263x/EXAMPLES_SENT_ENCODER.html

Another option is to use three channel peripheral interface mode of PRU-ICSSG where you can configure the clock for data out and keep pushing data into a TX FIFO. We use this for implementing absolute position sense encoder interfaces like Hiperface DSL, EnDAT, Tamagawa, etc (https://software-dl.ti.com/processor-industrial-sw/esd/motor_control_sdk/am243x/09_00_00_05/docs/api_guide_am243x/POSITION_SENSE.html).

You can refer to section 6.4.5.2.2.3.6 Three Channel Peripheral Interface in https://www.ti.com/lit/ug/spruim2h/spruim2h.pdf?ts=1700634782033&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FAM2434 for more details on this IO mode.

Regards
Dhaval

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AM2431: Help Using PRU for Data Encoding