isr + uart + thread testing

prj.conf

@@ -3,5 +3,6 @@ CONFIG_GPIO=y
 CONFIG_SERIAL=y
 CONFIG_CONSOLE=y
 CONFIG_UART_CONSOLE=y
-CONFIG_PRINTK=y
 CONFIG_UART_INTERRUPT_DRIVEN=y
+CONFIG_RING_BUFFER=y
+CONFIG_PRINTK=y

src/main.c

@@ -1,37 +1,130 @@
-#include <zephyr/devicetree.h>
-#include <zephyr/drivers/gpio.h>
 #include <zephyr/kernel.h>
+#include <zephyr/device.h>
+#include <zephyr/devicetree.h>
 #include <zephyr/drivers/uart.h>
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/sys/ring_buffer.h>
 
-#define SLEEP_MS 2000
+#include <string.h>
 
 #define LED_NODE DT_ALIAS(led0)
-#if !DT_NODE_HAS_STATUS(LED_NODE, okay)
-#error "led0 not enabled in devicetree"
-#endif
+
+#define UART_DEVICE_NODE DT_CHOSEN(zephyr_shell_uart)
+
+#define RX_BUF_SIZE 256
+#define LINE_BUF_SIZE 128
+#define THREAD_STACK 1024
+#define THREAD_PRIO 5
+
+// Ring buffer: callback writes, thread reads (could probably be a msg_queue too)
+RING_BUF_DECLARE(rx_buf, RX_BUF_SIZE);
+
+// Semaphore to wake the thread (name, initial count, max count)
+K_SEM_DEFINE(rx_sem, 0, 1);
+
+K_THREAD_STACK_DEFINE(rx_stack, THREAD_STACK);
+static struct k_thread rx_thread_data;
 
 static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(LED_NODE, gpios);
+static const struct device *uart = DEVICE_DT_GET(DT_NODELABEL(lpuart1));
+
+void uart_print(const char buffer[]);
+void uart_println(const char buffer[]);
+void uart_cb(const struct device *dev, void *user_data);
+static void rx_thread(void *p1, void *p2, void *p3);
 
 int main(void)
 {
-  printk("app started\n");
-
-  if (!gpio_is_ready_dt(&led))
+  if (!device_is_ready(uart))
   {
-    printk("LED GPIO not ready\n");
-    return 0;
+    printk("UART not ready\n");
+    return -1;
   }
 
-  int ret = gpio_pin_configure_dt(&led, GPIO_OUTPUT_ACTIVE);
-  if (ret < 0)
-  {
-    printk("LED GPIO configure failed: %d\n", ret);
+  // Set up interrupt-driven RX
+  uart_irq_callback_set(uart, uart_cb);
+  uart_irq_rx_enable(uart);
+
+  // Spawn the processing thread
+  k_thread_create(&rx_thread_data, rx_stack,
+                  THREAD_STACK,
+                  rx_thread, NULL, NULL, NULL,
+                  THREAD_PRIO, 0, K_NO_WAIT);
+
+  printk("UART ready — type something!\r\n");
+
   return 0;
+}
+
+// ============= Helpers =============
+
+void uart_print(const char buffer[])
+{
+  size_t len = strlen(buffer);
+  for (size_t i = 0; i < len; i++)
+    uart_poll_out(uart, buffer[i]);
+}
+
+void uart_println(const char buffer[])
+{
+  uart_print(buffer);
+  uart_poll_out(uart, '\r');
+  uart_poll_out(uart, '\n');
+}
+
+// ============= Callbacks =============
+void uart_cb(const struct device *dev, void *user_data)
+{
+  uint8_t byte;
+  while (uart_irq_update(dev) && uart_irq_rx_ready(dev))
+  {
+    if (uart_fifo_read(dev, &byte, 1) == 1)
+    {
+      ring_buf_put(&rx_buf, &byte, 1);
+    }
   }
 
-  char incoming;
-  int i = 0;
+  // wake up thread
+  k_sem_give(&rx_sem);
+}
+
+// ============= Threads =============
+static void rx_thread(void *p1, void *p2, void *p3)
+{
+  char line[LINE_BUF_SIZE];
+  size_t pos = 0;
+
   while (1)
   {
+    k_sem_take(&rx_sem, K_FOREVER);
+
+    uint8_t byte;
+    while (ring_buf_get(&rx_buf, &byte, 1) == 1)
+    {
+
+      // Echo the character back
+      uart_poll_out(uart, byte);
+
+      if (byte == '\r' || byte == '\n')
+      {
+        if (pos > 0)
+        {
+          line[pos] = '\0';
+
+          printk("\r\n");
+          printk("─────────────────────────────\r\n");
+          printk("│ RX: %-24s \r\n", line);
+          printk("│ Len: %-3d, Time: %-10u \r\n",
+                 pos, k_uptime_get_32());
+          printk("─────────────────────────────\r\n");
+
+          pos = 0;
+        }
+      }
+      else if (pos < LINE_BUF_SIZE - 1)
+      {
+        line[pos++] = byte;
+      }
+    }
   }
 }