How shall the SPI0 pins be configured for the SPI communication to work in loopback mode

General Discussion
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1

Hi support

I am working with the SPI communication in the BeagleBone Black. I want the SPI0 to act as a SPI master. Before connecting in a SPI slave, I want to test the SPI full duplex communication in loopback mode which simply means I am connecting a jumper between P9.18 (spi0_d0) and P9.21 (spi0_d1). But is there any specific pinmux configuration that is recommended for this loopback communication to work?

This is what I am currently using:
0x950 0x30 /* spi0_sclk, PIN_INPUT_PULLUP | MUX_MODE0 /
0x954 0x30 / spi0_d0, PIN_INPUT_PULLUP | MUX_MODE0 /
0x958 0x10 / spi0_d1, PIN_OUTPUT_PULLUP | MUX_MODE0 /
0x95C 0x10 / spi0_cs0, PIN_OUTPUT_PULLUP | MUX_MODE0 */

Any suggestion/comment would be much appreciated.

Kind regards
Aravindh

2

Hi @arre24 there’s a known ‘bug’ in the spi pinmux on am335x, that TI documented a few years ago…

These need to be set as PIN_INPUT/MODE0, for spi to work properly.

Regards,

3

Hi

Now the SPI0 full duplex loopback communication is working. Thanks for the support.

Kind regards
Aravindh