TWI reading the same data from registers

RE: TWI reading the same data from registers

Edvin — Tue, 23 Jul 2019 09:23:22 GMT

Hello,

Sorry for the late reply. I was out of office for a couple of weeks, and we are in general a bit short staffed during the summer.

I don't know how to do this exactly, other than using the events and tasks, as described here, and using PPI to trigger the next task based on the events.

The PPI may not be too easy to get your head around. You can either use the ppi drivers that are used in the SDK\examples\peripheral\ppi, or you can use the PPI registers directly, like it is done in the example attached in my first reply in this ticket. Note that this is not TWI, but an example that uses PPI and a timer to generate PWM signals. The timer events triggers the GPIOTE tasks, so in your case, you would want the TWI events to trigger the next TWI tasks.

RE: TWI reading the same data from registers

sridharnaidu — Mon, 08 Jul 2019 12:54:20 GMT

Hi Edvin

Can you give input on implementing the mentioned Master repeated start sequence?

RE: TWI reading the same data from registers

Edvin — Thu, 04 Jul 2019 10:37:15 GMT

Hello,

Sorry for the late reply.

It looks like what you are looking for is not a standard NRF_DRV_TWI_XFER_TXRX, but rather a NRF_DRV_TWI_XFER_TXRXTXRX (with no STOP signal in between). This is not supported by the driver by default.

I can't find any mentions in the drivers regarding NO_STOP flags in TWI RX mode, only in TX, so I am not sure whether it is possible, although it looks like the TWIM peripheral supports this.

Maybe you can give it a go to use the TWI registeres as described in the link above to see if you can get the behavior that the sensor expects.