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

[Chitrang Talaviya]

YEs you are right there is no official UART Tx pin. But I configured a GPIO as UART so that is why I am saying the UART Tx pin. In this configuration where the UART is acting as the CS driver, do you thank I sould use separate GPIOs for chip select. Do you think using the UART driver for chip select is giving the issue. Or do you think there is a connection issue like the wires I am using are having some noise so that I am reading the wrong WHO_AM_I values for some sensors(btw if I connect each sensor individually then I am able to read the correct values)