SPI overwrite by GPIO input

RE: SPI overwrite by GPIO input

Kenneth — Mon, 09 Dec 2019 17:04:57 GMT

How about using one of the SPIM instances that don't have hardware support for CSN (e.g 0-2), then you can configure/use the CSN pin as you see fit at any time. Just set CSN pin to NRFX_SPIM_PIN_NOT_USED during init of SPIM (then the driver will not use the CSN pin at all). Then you can from the application set CSN as any GPIO as you wish at any time, though you likely want to set it low before you start spi transfer, and clear it afterwards.

RE: SPI overwrite by GPIO input

Bar — Mon, 09 Dec 2019 16:58:28 GMT

Hi Kenneth. I found the reason for the current. The AD7770 with no power make a path threw the protecting diode from CS "1" to VDD "0". So I need an input. I try to make the SPI disable then the SEL.CS disconnect (there isn't unused in the SPI config). and then config that pin to GPIO input. But when I need again the SPI to active I need to reconfig it as in SPI_init. and for that I need first uninit to that SPI.

Bar.

RE: SPI overwrite by GPIO input

Kenneth — Mon, 09 Dec 2019 12:47:36 GMT

Not sure how the CS pin is drawing current, can it be that VDD to AD7770 is cut, and you are sourcing current through the CS pin to the AD7770? If you have an unused GPIO I assume you could just disable SPIM, reconfigure PSEL.CSN to unused pin, configure GPIO, and enable SPIM again.

Kenneth