SPI master and slave loop back test, but the slave is receive 0x00 bytes at all

[huaminhtuan]

Hi everyone,

I am using NRF52832 and I use SPI as communication protocol. I check my SPI master by connect its MOSI and MISO pins together, and it works correctly. Now I want to check my SPI slave. I connect SPI slave and SPI master as below:

SPI master------SPI slave
MOSI-------------MOSI
MISO-------------MISO
SCK--------------SCK
CSN--------------CSN

When I send the string "Nordic is the best" from SPI master to SPI slave, all slave bytes received i s 20 0x00 bytes. Can you help me please? Thanks for reading!

[huaminhtuan]

hi Jørgen Holmefjord,

I set up SPIM0 as master and SPIS1 as slave and I use pins below

SPI master------SPI slave
p13 MOSI-------------MOSI p17
p14 MISO-------------MISO p18
p12 SCK--------------SCK p16
p11 CSN--------------CSN p15

I also check SPI lines with a oscilloscope and it work correctly.

[Jørgen Holmefjord]

Have you modified the PCA10040 board? Note that P0.13-P0.18 is used for buttons and LEDs, and might not work with other peripherals without modification to the board and application. Could you upload your code for debugging?

[PartTimeCode]

Hi Jorgen,

I am new to Nordic. I am also trying to create an SPI master and Slave on a single nRF52832 (PCA10040) Development board with SDK Version 15.0. I have created a slave instance in the SPI example (using SPIS example as reference).

Pin mapping:

#	PIN NAME	MASTER	SLAVE
1	MISO	Pin 28	Pin 05
2	MOSI	Pin 04	Pin 06
3	CSN	Pin 29	Pin 07
4	CLK	Pin 03	Pin 08

My issue is that the master is receiving the correct data but the slave is not.

I have checked on logic anlayzer, data on MOSI pin is valid, however, slave receive buffer does not show me correct data.

[Jørgen Holmefjord]

GPIOs P0.05-P0.08 is used for the UART interface on the nRF52 DK. Did you cut SB22-25 to disconnect the pins from the interface MCU, and make sure you do not initialize UART or NRF_LOG with UART backend in your application?

[PartTimeCode]

I changed the slave pins to GPIO Pins (with no additional functionality) which gives me correct output. Thanks