SPIM MOSI sending 0x00 even though TX buffer is non-zero

[KarthikS27]

Hi, I'm using the following SPIM setup on the nrf54L15pdk evaluation board:

spi00: spi@4a000 {

compatible = "nordic,nrf-spim";
#address-cells = <1>;
#size-cells = <0>;
reg = <0x4a000 0x1000>;
interrupts = <74 NRF_DEFAULT_IRQ_PRIORITY>;
max-frequency = <DT_FREQ_M(32)>;
easydma-maxcnt-bits = <16>;
rx-delay-supported;
rx-delay = <1>;
status = "okay";
cs-gpios = <&gpio2 10 GPIO_ACTIVE_LOW>;
pinctrl-0 = <&spi00_default>;
pinctrl-names = "default";

spi_foo: spi_foo@0 {

reg = <0>;

spi-max-frequency = <2000000>;

label = "spi_foo";

};

};

spi00_default: spi00_default {

group1 {

psels =

<NRF_PSEL(SPIM_SCK, 2, 6)>,
<NRF_PSEL(SPIM_MOSI, 2, 2)>,
<NRF_PSEL(SPIM_MISO, 2, 9)>;

};

};

When I send a tx_buffer (for example, send {0xAA, 0xBB, 0xCC}) through spi_transceive_dt(), I see the MOSI line being held low to 0mV, but the SCK line is functional. I'm currently doing a loopback test where MOSI feeds into MISO and no peripheral is connected so that I can verify that MOSI and MISO works as expected. However, I still see MOSI being held at 0mV even when disconnected from the MISO pin.

What would I need configured to ensure data is being sent through the MOSI pin and likewise to ensure data is being received through the MISO pin?

[Maria Gilje]

Hello,

Have you followed the guidelines to use P2.02 as a GPIO instead of the default (memory)? This information can be found here, and in short you need to cut SB13 and short SB19.

P2.09 is connected to LED0 by default (source). Disable LED0 to use P2.09 for SPI_MISO instead with something like:

&led0 {
    status="disabled";
};

If the above does not help, you may need to also configure SPIS for the device.

Also, let me know if you don't have an nRF54L15DK available. We should be able to provide you with one/some if you don't them available. 

Best regards,

Maria

[KarthikS27]

Hi Maria,

Thanks for letting me know about the modifications needed for P2.02 and P2.09. I already have led0 disabled. For the sake of testing, I tried using P1.11 and P1.12 for MOSI and MISO respectively. I've been able to use these pins for I2C reliably, however, I still see the lines being held low for SPI.

My board version is 0.8.1 and I have been running DK firmware on it.

I'll try again after configuring SPIS for the device