MSPM0G3507-Q1: SPI in 3-Wire mode with shared PICO and POCI wire

Dominik Maier

Part Number: MSPM0G3507-Q1
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hi guys,

i have the following 3-wire configuration

The PICO and POCI wire is shared, because the slave just a common IO SPI wire. Is this configuration possible because in CCS there is only Motorola 3-wire configuration without a cs wire possible?

Maybe the TI synchronous mode works for but I am not sure?

Is there a way to run such a configuration?

Thanks

Kind regards

Dominik

7 months ago

0 Diego Abad Sajamin 7 months ago

TI__Genius 14912 points

Hi Dominik,
SYSCONFIG only offers the configurations you currently see. However, you can manually control the cs wire through a GPIO. Moreover, as long as your external hardware is set and the proper code is configured in CCS, you should be able to run this mode.
Best Regards,
Diego Abad

0 Bruce McKenney 7 months ago

Guru 99245 points

What slave device are you using?

Generally, you can't share PICO and POCI since the master (controller) always drives PICO and the slave (peripheral) drives POCI as needed, so there is a bus conflict.

Microwire is a variant (kind of a "first cousin") of SPI which is capable of sharing PICO and POCI, but the wire-level signaling is different so your slave device needs to support it (thus my question).

The MSPM0 SPI unit implements Microwire, though it isn't really described in the TRM and you have to work around DriverLib a little to use it. But at the coding level it's pretty much the same as SPI.

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MSPM0G3507-Q1: SPI in 3-Wire mode with shared PICO and POCI wire