Issue with the connection between nrf54l15dk and sx1261m2bas shield

[Aanjaneya24]

Hello ,

I am currently working on a project to interface an nRF54L15 Development Kit (PCA10156) with a Semtech SX1261 LoRa module (specifically, the SX1261MB2BAS shield). I am using the nRF Connect SDK and am facing a persistent issue with establishing basic SPI communication.
My initial goal is to perform a simple sanity check: read a known register from the SX1261 to verify that the physical and logical connections are working. Despite my efforts and debugging, I am unable to get a valid response from the SX1261. Kindly help me out, at a point i'm stuck with it. Sharing my whole problem status please help me out.
=987655.pdf
OUTPUT RECEIVING : Transmission failed

CODE FILE :
aanjaneyapandey@Mac lora_trx_app % tree
.
├── boards
│ └── nrf54l15dk_nrf54l15_cpuapp.overlay
├── CMakeLists.txt
├── prj.conf
└── src
└── main.c
nrf54l15dk_nrf54l15_cpuapp.overlay :
&spi00{
status = "okay";
cs-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>; // P2.05 - CS
lora0: sx1261@0 {
compatible = "semtech,sx1261";
reg = <0>; // CS index
spi-max-frequency = <8000000>;
reset-gpios = <&gpio2 6 GPIO_ACTIVE_LOW>; // P2.06
dio1-gpios = <&gpio1 15 GPIO_ACTIVE_HIGH>; // P1.15
busy-gpios = <&gpio1 11 GPIO_ACTIVE_HIGH>; // P1.11
};
};
Main.c :
#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/lora.h>
#include <zephyr/logging/log.h>
#include <string.h>
LOG_MODULE_REGISTER(main, LOG_LEVEL_DBG); // Enables serial log over UART
/**

• @brief Main function of the LoRa transmitter app.
• Initializes LoRa, sends periodic packets, and logs transmission status.
• @return int Always returns 0.
  */
  int main(void) {
  const struct device *lora_dev = DEVICE_DT_GET(DT_NODELABEL(lora0));
  if (!device_is_ready(lora_dev)) {
  LOG_ERR("LoRa device not ready");
  return;
  }
  struct lora_modem_config config = {
  .frequency = 868000000, // Use 433E6 / 915E6 if needed
  .bandwidth = BW_125_KHZ,
  .datarate = SF_7,
  .preamble_len = 8,
  .coding_rate = CR_4_5,
  .tx_power = 14,
  .tx = true
  };
  int ret = lora_config(lora_dev, &config);
  if (ret < 0) {
  LOG_ERR("Failed to configure LoRa: %d"
  , ret);
  return;
  }
  LOG_INF("LoRa config done. Waiting before transmit...");
  k_sleep(K_MSEC(200)); // Give time to settle
  char msg[] = "Hello from nRF54L15 + SX1261!";
  while (1) {
  ret = lora_send(lora_dev, msg, strlen(msg));
  if (ret == -11) {
  LOG_WRN("SX1261 busy. Retrying...");
  k_sleep(K_MSEC(100)); // Wait before retry
  continue;
  } else if (ret < 0) {
  LOG_ERR("LoRa send failed: %d", ret);
  } else {
  LOG_INF("Message sent: %s", msg);
  }
  k_sleep(K_SECONDS(5));
  }
  return 0;
  }
  CMakeLists.txt :
  cmake_minimum_required(VERSION 3.20.0)
  find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
  project(lora_trx_app)
  target_sources(app PRIVATE src/main.c)
  prj.conf :

Core

CONFIG_GPIO=y
CONFIG_SPI=y

LoRa

CONFIG_LORA=y
CONFIG_LORA_INIT_PRIORITY=90

Serial + Logging

CONFIG_SERIAL=y
CONFIG_CONSOLE=y
CONFIG_UART_CONSOLE=y
CONFIG_LOG=y
CONFIG_LOG_MODE_DEFERRED=y
CONFIG_LOG_BACKEND_UART=y
CONFIG_LOG_DEFAULT_LEVEL=3
SDK : nRF Connect SDK v2.9.1
Toolchain : nRF Connect SDK Toolchain v2.9.1
Circuit Diagram and Pin connection :