Im not sure where i'm going wrong but SPI just won't work

CMakeLists.txt

@@ -6,10 +6,10 @@ endif()
 
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
-
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2")
+#
+# set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
+# set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
+# set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2")
 
 project(passr)
 

boards/nrf52840dk_nrf52840.overlay

@@ -15,20 +15,49 @@
 			low-power-enable;
 		};
 	};
+
+	spi_slave_default: spi_slave_default {
+		group1 {
+			psels = <NRF_PSEL(SPIS_SCK, 1, 1)>,
+					<NRF_PSEL(SPIS_MOSI, 1, 2)>,
+					<NRF_PSEL(SPIS_MISO, 1, 3)>,
+					<NRF_PSEL(SPIS_CSN, 1, 4)>;
+		};
+	};
+
+	spi_slave_sleep: spi_slave_sleep {
+		group1 {
+			psels = <NRF_PSEL(SPIS_SCK, 1, 1)>,
+					<NRF_PSEL(SPIS_MOSI, 1, 2)>,
+					<NRF_PSEL(SPIS_MISO, 1, 3)>,
+					<NRF_PSEL(SPIS_CSN, 1, 4)>;
+			low-power-enable;
+		};
+	};
 };
 
-spi_master: &spi0 {
+my_spi_master: &spi3 {
 	compatible = "nordic,nrf-spim";
 	status = "okay";
 	pinctrl-0 = <&spi_master_default>;
 	pinctrl-1 = <&spi_master_sleep>;
 	pinctrl-names = "default", "sleep";
 	cs-gpios = <&gpio0 28 GPIO_ACTIVE_LOW>;
-	reg_spi_master: spi-dev-a@0 {
+	reg_my_spi_master: spi-dev-a@0 {
 		reg = <0>;
 	};
 };
 
+my_spi_slave: &spi1 {
+	compatible = "nordic,nrf-spis";
+	status = "okay";
+	pinctrl-0 = <&spi_slave_default>;
+	pinctrl-1 = <&spi_slave_sleep>;
+	pinctrl-names = "default", "sleep";
+	def-char = <0x00>;
+};
+
+// By default uart1 will occupy P1.01 and P1.02. In order to make these pins available, disable uart1
 &uart1 {
 	status="disabled";
 };

src/main.c

@@ -1,39 +1,37 @@
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 #include <zephyr/kernel.h>
 #include <zephyr/device.h>
 #include <zephyr/devicetree.h>
 #include <zephyr/drivers/gpio.h>
 #include <zephyr/drivers/spi.h>
-#include <zephyr/sys/printk.h>
 
+/* 1000 msec = 1 sec */
 #define SLEEP_TIME_MS   1000
 
+/* The devicetree node identifier for the "led0" alias. */
 #define LED0_NODE DT_ALIAS(led0)
-#define SPI_MASTER DT_NODELABEL(spi_master)
-#define SPI_SLAVE  DT_NODELABEL(spi_slave)
 
-static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(LED0_NODE, gpios);
+#define MY_SPI_MASTER DT_NODELABEL(my_spi_master)
+
+#define MY_SPI_SLAVE  DT_NODELABEL(my_spi_slave)
 
 // SPI master functionality
 const struct device *spi_dev;
 static struct k_poll_signal spi_done_sig = K_POLL_SIGNAL_INITIALIZER(spi_done_sig);
 
-const struct spi_cs_control spim_cs = {
-	.gpio = SPI_CS_GPIOS_DT_SPEC_GET(DT_NODELABEL(reg_spi_master)),
+struct spi_cs_control spim_cs = {
+	.gpio = SPI_CS_GPIOS_DT_SPEC_GET(DT_NODELABEL(reg_my_spi_master)),
 	.delay = 0,
 };
 
-static const struct spi_config spi_cfg = {
-    .operation = SPI_WORD_SET(8) | SPI_TRANSFER_MSB |
-        SPI_MODE_CPOL | SPI_MODE_CPHA,
-    .frequency = 10000,
-    .slave = 0,
-    .cs = {{(const struct device*)&spim_cs}},
-};
-
 static void spi_init(void)
 {
-    printk("SPI master init\n");
-	spi_dev = DEVICE_DT_GET(SPI_MASTER);
+	spi_dev = DEVICE_DT_GET(MY_SPI_MASTER);
 	if(!device_is_ready(spi_dev)) {
 		printk("SPI master device not ready!\n");
 	}
@@ -42,6 +40,13 @@ static void spi_init(void)
 	}
 }
 
+static const struct spi_config spi_cfg = {
+	.operation = SPI_WORD_SET(8) | SPI_TRANSFER_MSB |
+				 SPI_MODE_CPOL | SPI_MODE_CPHA,
+	.frequency = 4000000,
+	.slave = 0,
+	.cs = &spim_cs,
+};
 
 static int spi_write_test_msg(void)
 {
@@ -58,7 +63,16 @@ static int spi_write_test_msg(void)
 		.count = 1
 	};
 
-    // Update the TX buffer with a rolling counter
+	struct spi_buf rx_buf = {
+		.buf = rx_buffer,
+		.len = sizeof(rx_buffer),
+	};
+	const struct spi_buf_set rx = {
+		.buffers = &rx_buf,
+		.count = 1
+	};
+
+	// Update the TX buffer with a rolling counter
 	tx_buffer[0] = counter++;
 	printk("SPI TX: 0x%.2x, 0x%.2x\n", tx_buffer[0], tx_buffer[1]);
 
@@ -66,7 +80,7 @@ static int spi_write_test_msg(void)
 	k_poll_signal_reset(&spi_done_sig);
 	
 	// Start transaction
-	int error = spi_transceive(spi_dev, &spi_cfg, &tx, NULL);
+	int error = spi_transceive_async(spi_dev, &spi_cfg, &tx, &rx, &spi_done_sig);
 	if(error != 0){
 		printk("SPI transceive error: %i\n", error);
 		return error;
@@ -81,6 +95,82 @@ static int spi_write_test_msg(void)
 	return 0;
 }
 
+// SPI slave functionality
+const struct device *spi_slave_dev;
+static struct k_poll_signal spi_slave_done_sig = K_POLL_SIGNAL_INITIALIZER(spi_slave_done_sig);
+
+static const struct spi_config spi_slave_cfg = {
+	.operation = SPI_WORD_SET(8) | SPI_TRANSFER_MSB |
+				 SPI_MODE_CPOL | SPI_MODE_CPHA | SPI_OP_MODE_SLAVE,
+	.frequency = 4000000,
+	.slave = 0,
+};
+
+static void spi_slave_init(void)
+{
+	spi_slave_dev = DEVICE_DT_GET(MY_SPI_SLAVE);
+	if(!device_is_ready(spi_dev)) {
+		printk("SPI slave device not ready!\n");
+	}
+}
+
+static uint8_t slave_tx_buffer[2];
+static uint8_t slave_rx_buffer[2];
+static int spi_slave_write_test_msg(void)
+{
+	static uint8_t counter = 0;
+
+
+	const struct spi_buf s_tx_buf = {
+		.buf = slave_tx_buffer,
+		.len = sizeof(slave_tx_buffer)
+	};
+	const struct spi_buf_set s_tx = {
+		.buffers = &s_tx_buf,
+		.count = 1
+	};
+
+	struct spi_buf s_rx_buf = {
+		.buf = slave_rx_buffer,
+		.len = sizeof(slave_rx_buffer),
+	};
+	const struct spi_buf_set s_rx = {
+		.buffers = &s_rx_buf,
+		.count = 1
+	};
+
+	// Update the TX buffer with a rolling counter
+	slave_tx_buffer[1] = counter++;
+	printk("SPI SLAVE TX: 0x%.2x, 0x%.2x\n", slave_tx_buffer[0], slave_tx_buffer[1]);
+
+	// Reset signal
+	k_poll_signal_reset(&spi_slave_done_sig);
+	
+	// Start transaction
+	int error = spi_transceive_async(spi_slave_dev, &spi_slave_cfg, &s_tx, &s_rx, &spi_slave_done_sig);
+	if(error != 0){
+		printk("SPI slave transceive error: %i\n", error);
+		return error;
+	}
+	return 0;
+}
+
+static int spi_slave_check_for_message(void)
+{
+	int signaled, result;
+	k_poll_signal_check(&spi_slave_done_sig, &signaled, &result);
+	if(signaled != 0){
+		return 0;
+	}
+	else return -1;
+}
+
+/*
+ * A build error on this line means your board is unsupported.
+ * See the sample documentation for information on how to fix this.
+ */
+static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(LED0_NODE, gpios);
+
 void main(void)
 {
 	int ret;
@@ -96,15 +186,26 @@ void main(void)
 
 	spi_init();
 
-	printk("SPI master started\n");
+	spi_slave_init();
+
+	printk("SPI master/slave example started\n");
+	
+	spi_slave_write_test_msg();
 
 	while (1) {
 		spi_write_test_msg();
 		ret = gpio_pin_toggle_dt(&led);
 		if (ret < 0) {
-            printk("Error toggling LED pin\n");
 			return;
 		}
 		k_msleep(SLEEP_TIME_MS);
+
+		if(spi_slave_check_for_message() == 0){
+			// Print the last received data
+			printk("SPI SLAVE RX: 0x%.2x, 0x%.2x\n", slave_rx_buffer[0], slave_rx_buffer[1]);
+			
+			// Prepare the next SPI slave transaction
+			spi_slave_write_test_msg();
+		}
 	}
 }