Greetings,
Using SDK v3.1.1 the SPI MISO signal appears to be actively driven by the nRF5280 for both my SPI1 and SPI2 configurations. In both cases there are no active SPI Slaves connected - just a loopback connection from MOSI to MISO. A SPI Master should NEVER drive MISO, only pull it down for when CS is negated. I suspect there's some magic pin configuration somewhere that's missing in the devicetree but I can't find anything. I read some other questions regarding this same problem that suggested a MISO pin should be explicitly configured as a GPIO input but that doesn't work either.
Here's my overlay portions for SPI1:
&spi1 {
compatible = "nordic,nrf-spim";
status = "okay";
pinctrl-0 = <&spi1_default>;
pinctrl-1 = <&spi1_sleep>;
pinctrl-names = "default", "sleep";
easydma-maxcnt-bits = <16>;
cs-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>, <&gpio0 11 GPIO_ACTIVE_LOW>;
module_nvm: module_nvm@0 {
compatible = "jedec,spi-nor"; /* TODO FIXME this needs to be set up for the module's non-volatile memory. */
reg = < 0 >;
spi-max-frequency = < 8000000 >;
label = "MODULE_MEMORY";
};
module_rtc: module_rtc@1 {
compatible = "jedec,spi-nor"; /* TODO FIXME this needs to be set up for the module's RTC. */
reg = < 0 >;
spi-max-frequency = < 8000000 >;
label = "MODULE_RTC";
};
};
&pinctrl {
spi1_default {
group1 {
psels = <NRF_PSEL(SPIM_SCK, 1, 8)>,
<NRF_PSEL(SPIM_MOSI, 1, 10)>;
};
group2 {
psels = <NRF_PSEL(SPIM_MISO, 1, 9)>;
bias-pull-down;
};
};
spi1_sleep {
group1 {
psels = <NRF_PSEL(SPIM_SCK, 1, 8)>,
<NRF_PSEL(SPIM_MOSI, 1, 10)>;
};
group2 {
psels = <NRF_PSEL(SPIM_MISO, 1, 9)>;
bias-pull-down;
};
};
};
