topic DSPI communication in ColdFire/68K Microcontrollers and Processors

DSPI communication

johnsonzhang1 — Wed, 10 Jul 2019 07:55:58 GMT

SPI communication, the pin DSPIPCS0/1/2/5 are used out.

Can i use the another common GPIO to select the CS for SPI communication ?

Re: DSPI communication

Hui_Ma — Thu, 11 Jul 2019 08:39:54 GMT

Hi,

Yes, customer can use the GPIO pin to emulate SPI chip select signal.

Please make sure during SPI communication, the SPI chip select should be active. Thanks.

Have a great day,
Mike

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Re: DSPI communication

TomE — Thu, 11 Jul 2019 23:44:51 GMT

Yes, this is possible. But it prevents you using all of the advanced features of the QSPI. Using its own chip-selects you can load the QSPI RAM with up to 16 transfers to different chips and let it run all of them automatically. To use a GPIO instead of a chip select the driver has to program one transfer only in the QSPI RAM, and then assert and deassert the chip select around that transfer.

If you're not using these features and don't need the efficiency, CPU offloading and speed, then it doesn't matter.

It might be better to swap spare GPIOs with any of the QSPI Chip Selects that are being used as GPIOs.

Also, if you can free up one chip-select, to have two QSPI CS pins, then you can use an external address decoder to generate three chip-selects. Or three pins to generate seven chip-selects.

Tom