How many max SPI slave sensor I can connect with Nrf52840 via SPIM

[Chitrang Talaviya]

Hello Folks,

I am using PCA 10056 Eval board. I am using SPIM0 to connect 5 slave sensors. The Chip select is done by the UART Tx pin. So If I send 0x01 over UARt then the sensor- 1 will be selected.

UART Tx byte -- Sensor 0x01 -- 1 0x02 -- 2 etc

Sensors are LSM6DSL

I have five sensors connected via SPIM0 to nordic nrf52840. I am only able to get the reading from 1 or 2 sensors only which is connected closely to nordic. Is there any max limit with the current SPIM hardware and software limitations in terms of max slaves?

ALso, How to change the CS duration and RX delay timing of the SPIM hardware using the SDK 14?

Thank you

[RK]

If that's actually the case, that after the UART byte has been clocked out fully then the chip needs 15us more before the output is ready (not that I see anything like that kind of delay on the spec sheet for the SLG46536V, it's a few hundred nanos in most cases) then using a delay is fine. If the 15us is the time taken for the UART data to be sent, then a fixed delay is the wrong thing to use and you should poll/interrupt the UART to know when it's finished sending. The latter is what I see more often than I'd like.