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

[Dave_couling]

SPI and UART are two different data interfaces and two different drivers. So I'm confused what exactly you are trying to do here. Are you using UART or SPI?

NoteL UART is NOT a bus protocol. Meaning its ONLY one device to one device. SPI is a bus protocol so you can attached multiple devices on the data data lines. HOWEVER you need a different CS pin/line assigned to each sensor device.