LORA module RFM95 error sending message connected on custom SPI pins of MDBT42Q (nRF52832)

[Luis Felipe]

Hi, here I have a custom made board that has a MDBT42Q module (nRF52832 based) and has connected a RFM95W LoRA module, using this simple send lora code:

#include <zephyr/device.h>
#include <zephyr/drivers/lora.h>
#include <errno.h>
#include <zephyr/sys/util.h>
#include <zephyr/zephyr.h>


#define DEFAULT_RADIO_NODE DT_ALIAS(lora0)
BUILD_ASSERT(DT_NODE_HAS_STATUS(DEFAULT_RADIO_NODE, okay),
	     "No default LoRa radio specified in DT");

#define MAX_DATA_LEN 2

#define LOG_LEVEL CONFIG_LOG_DEFAULT_LEVEL
#include <zephyr/logging/log.h>

LOG_MODULE_REGISTER(lora_test);

char data[MAX_DATA_LEN] = {'h', 'e'};

void main(void)
{
        const struct device *lora_dev = DEVICE_DT_GET(DEFAULT_RADIO_NODE);
	struct lora_modem_config config;
	int ret;

	if (!device_is_ready(lora_dev)) {
		LOG_ERR("%s Device not ready", lora_dev->name);
		return;
	}

	config.frequency = 904300000;
	config.bandwidth = BW_125_KHZ;
	config.datarate = SF_6;
	config.preamble_len = 8;
	config.coding_rate = CR_4_5;
	config.tx_power = 4;

	config.tx = true;

	ret = lora_config(lora_dev, &config);
	if (ret < 0) {
		LOG_ERR("LoRa config failed");
		return;
	}

	while (1) {
                ret = lora_send(lora_dev, data, MAX_DATA_LEN);
		if (ret < 0) {
			LOG_ERR("LoRa send failed");
			return;
		}
		LOG_INF("Data sent!");
		k_sleep(K_MSEC(1000));
	}
}

I getting this error on RTT console (the custom board can only be accesses by JTAG, I'm using a JLink):

00> [00:00:00.201,507] <inf> sx127x: SX127x version 0x12 found
00> *** Booting Zephyr OS build v3.1.99-ncs1-1  ***
00> 
00> [00:00:00.272,399] <dbg> lorawan: lorawan_init: LoRaMAC Initialized
00> [00:00:00.284,454] <dbg> sx12xx_common: sx12xx_lora_send: Expected air time of 2 bytes = 19ms
00> [00:00:00.334,228] <err> sx12xx_common: Packet transmission failed!
00> [00:00:00.343,811] <inf> lora_test: Data sent!
00> [00:00:01.353,454] <dbg> sx12xx_common: sx12xx_lora_send: Expected air time of 2 bytes = 19ms
00> [00:00:01.403,228] <err> sx12xx_common: Packet transmission failed!
00> [00:00:01.412,811] <inf> lora_test: Data sent!
00> [00:00:02.422,454] <dbg> sx12xx_common: sx12xx_lora_send: Expected air time of 2 bytes = 19ms
00> [00:00:02.472,167] <err> sx12xx_common: Packet transmission failed!
00> [00:00:02.481,750] <inf> lora_test: Data sent!

Really i dont underestand why the packet transmission is failing, need help about how to debug this error, the device used to build the zephyr project is the nrf52dk_nrf52832, the command used was west build -b nrf52dk_nrf52832 .. The overlay that I'm using is:

// Custom PINS
&pinctrl {
	spi0_default: spi0_default {
		group1 {
			psels = <NRF_PSEL(SPIM_SCK, 0, 19)>,
				<NRF_PSEL(SPIM_MOSI, 0, 18)>,
				<NRF_PSEL(SPIM_MISO, 0, 14)>;
		};
	};

	spi0_sleep: spi0_sleep {
		group1 {
			psels = <NRF_PSEL(SPIM_SCK, 0, 19)>,
				<NRF_PSEL(SPIM_MOSI, 0, 18)>,
				<NRF_PSEL(SPIM_MISO, 0, 14)>;
			low-power-enable;
		};
	};
};


&spi0 {
    status = "okay";
    compatible = "nordic,nrf-spi";

    pinctrl-0 = <&spi0_default>;
    pinctrl-1 = <&spi0_sleep>;
    pinctrl-names = "default", "sleep";

    cs-gpios = <&gpio0 20 GPIO_ACTIVE_LOW>;
    
    lora: sx1276@0 {
        compatible = "semtech,sx1276";
        reg = <0>;
        label = "sx1276";

        reset-gpios = <&gpio0 4 GPIO_ACTIVE_LOW>;

        dio-gpios = <&gpio0 11 (GPIO_PULL_DOWN | GPIO_ACTIVE_HIGH)>,
            <&gpio0 12 (GPIO_PULL_DOWN | GPIO_ACTIVE_HIGH)>,
            <&gpio0 13 (GPIO_PULL_DOWN | GPIO_ACTIVE_HIGH)>;

        spi-max-frequency = <10000000>;
        power-amplifier-output = "pa-boost";
    };
};

/ {
    aliases {
       lora0 = &lora;
  };
};

with this prj.conf:

CONFIG_LOG=y
CONFIG_SHELL=y
CONFIG_LOG_MODE_DEFERRED=n
CONFIG_LOG_MODE_IMMEDIATE=y

CONFIG_DEBUG_THREAD_INFO=y
CONFIG_PRINTK=y

CONFIG_USE_SEGGER_RTT=y
CONFIG_RTT_CONSOLE=y

CONFIG_BOOTLOADER_MCUBOOT=y

CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048

# Enable SPI
CONFIG_SPI=y
CONFIG_SPI_NRFX=y

# Enable the SX12XX radio driver for Lora
CONFIG_LORA=y
CONFIG_LORA_LOG_LEVEL_DBG=y
CONFIG_LORA_SX12XX=y
CONFIG_LORA_SX127X=y

# Enable the LoraWAN stack
CONFIG_LORAWAN=y
CONFIG_LORAWAN_LOG_LEVEL_DBG=y
CONFIG_HAS_SEMTECH_LORAMAC=y
CONFIG_HAS_SEMTECH_SOFT_SE=y
CONFIG_HAS_SEMTECH_RADIO_DRIVERS=y

# Configure LoraWAN Region to be used
CONFIG_LORAMAC_REGION_US915=y

The reference of the custom board connections are:

[Sigurd]

Hi,

For issues with this lora driver, I would recommend checking if someone in the zephyr community(Zephyr Discord) might have some clues.

https://docs.zephyrproject.org/latest/develop/getting_started/index.html#asking-for-help

But here is some things you can try to change in the overlay:

1) Use compatible = "nordic,nrf-spim"; , instead of compatible = "nordic,nrf-spi";

2) Reduce SPI frequency. Set it to spi-max-frequency = <8000000>;

[Luis Felipe]

Thanks for response, i made these changes but now with the "nordic,nrf-spim" compatible sems that i missed something on the overlay that i need to add because:

/zephyr/drivers/lora/sx127x.c:177: undefined reference to `__device_dts_ord_106'

[Sigurd]

It could be that the lora driver only works with nordic,nrf-spi. You could also try to only apply the frequency changes, and see if that itself fixes anything.

[Luis Felipe]

Tested already without success, i think that the problem is with the definition of the device, because i have a code with the "old" FreeRTOS framework that's works, but is not mine, so I am coding this new using the zephyr framework. So I think that the selection of the "nrf52dk_nrf52832" zephyr board can have some definitions that break something. Example I changed the SPIO-0 definition because who made the board connect the LORA module to others ports and not to default ones, but works because the other code is working.

[Sigurd]

Ok, I see. Also, if you think there is something wrong with the SPI communication, then probing the GPIO SPI pins with a logic analyzer might be useful as well.