Implement SerialUSB

Author: facchinm

cores/arduino/Arduino.h

@@ -108,5 +108,6 @@ int digitalPinToInterrupt(pin_size_t pin);
 
 #include <variant.h>
 #ifdef __cplusplus
+#include <SerialUSB.h>
 #include <zephyrSerial.h>
-#endif // __cplusplus
+#endif // __cplusplus

cores/arduino/SerialUSB.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2024 Arduino SA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include <zephyrSerial.h>
+
+namespace arduino {
+
+class SerialUSB_ : public ZephyrSerial {
+
+public:
+	SerialUSB_(const struct device *dev) : ZephyrSerial(dev) { }
+	void begin(unsigned long baudrate, uint16_t config);
+	void begin(unsigned long baudrate) { begin(baudrate, SERIAL_8N1); }
+
+	operator bool() override;
+
+protected:
+	uint32_t dtr = 0;
+	uint32_t baudrate;
+	void _baudChangeHandler();
+	static void _baudChangeDispatch(struct k_timer *timer);
+
+private:
+	struct k_timer baud_timer;
+	bool started = false;
+};
+}  // namespace arduino
+
+#if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), cdc_acm)
+extern arduino::SerialUSB_ Serial;
+#endif

cores/arduino/USB.cpp

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2024 Arduino SA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+// Make PluggableUSB link happy
+#include "api/PluggableUSB.h"
+
+static uint8_t _epBuffer[1];
+void* epBuffer(unsigned int n) {
+    return &_epBuffer[n];
+};
+
+arduino::PluggableUSB_::PluggableUSB_() {}
+
+#include <zephyr/devicetree.h>
+#include <zephyr/drivers/uart.h>
+#include <zephyr/drivers/uart/cdc_acm.h>
+#include <zephyr/usb/usb_device.h>
+#include <SerialUSB.h>
+
+#if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), cdc_acm)
+const struct device *const usb_dev = DEVICE_DT_GET(DT_PHANDLE_BY_IDX(DT_PATH(zephyr_user), cdc_acm, 0));
+
+void usb_status_cb(enum usb_dc_status_code cb_status, const uint8_t *param) {
+    if (cb_status == USB_DC_CONFIGURED) {
+
+    }
+}
+
+void __attribute__((weak)) _on_1200_bps() {
+    NVIC_SystemReset();
+}
+
+void arduino::SerialUSB_::_baudChangeHandler()
+{
+    uart_line_ctrl_get(uart, UART_LINE_CTRL_BAUD_RATE, &baudrate);
+    if (baudrate == 1200) {
+        usb_disable();
+        _on_1200_bps();
+    }
+}
+
+static void _baudChangeHandler(const struct device *dev, uint32_t rate)
+{
+    if (rate == 1200) {
+        usb_disable();
+        _on_1200_bps();
+    }
+}
+
+void arduino::SerialUSB_::_baudChangeDispatch(struct k_timer *timer) {
+    arduino::SerialUSB_* dev = (arduino::SerialUSB_*)k_timer_user_data_get(timer);
+    dev->_baudChangeHandler();
+}
+
+
+void arduino::SerialUSB_::begin(unsigned long baudrate, uint16_t config) {
+    if (!started) {
+        usb_enable(NULL);
+        #ifndef CONFIG_CDC_ACM_DTE_RATE_CALLBACK_SUPPORT
+        k_timer_init(&baud_timer, SerialUSB_::_baudChangeDispatch, NULL);
+        k_timer_user_data_set(&baud_timer, this);
+        k_timer_start(&baud_timer, K_MSEC(100), K_MSEC(100));
+        #else
+        cdc_acm_dte_rate_callback_set(usb_dev, ::_baudChangeHandler);
+        #endif
+        ZephyrSerial::begin(baudrate, config);
+        started = true;
+    }
+}
+
+arduino::SerialUSB_::operator bool() {
+    uart_line_ctrl_get(uart, UART_LINE_CTRL_DTR, &dtr);
+    return dtr;
+}
+
+arduino::SerialUSB_ Serial(usb_dev);
+#endif

cores/arduino/main.cpp

@@ -10,6 +10,9 @@
 #endif
 
 int main(void) {
+#if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), cdc_acm)
+  Serial.begin(115200);
+#endif
   setup();
 
   for (;;) {

cores/arduino/zephyrSerial.cpp

@@ -9,6 +9,7 @@
 
 #include <api/HardwareSerial.h>
 #include <zephyrSerial.h>
+#include <Arduino.h>
 
 namespace
 {
@@ -164,7 +165,10 @@ size_t arduino::ZephyrSerial::write(const uint8_t *buffer, size_t size)
 }
 
 #if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), serials)
+#if !DT_NODE_HAS_PROP(DT_PATH(zephyr_user), cdc_acm)
+// If CDC USB, use that object as Serial (and SerialUSB)
 arduino::ZephyrSerial Serial(DEVICE_DT_GET(DT_PHANDLE_BY_IDX(DT_PATH(zephyr_user), serials, 0)));
+#endif
 #if (DT_PROP_LEN(DT_PATH(zephyr_user), serials) > 1)
 #define ARDUINO_SERIAL_DEFINED_0 1
 

cores/arduino/zephyrSerial.h

@@ -7,8 +7,6 @@
 #pragma once
 
 #include <zephyr/sys/ring_buffer.h>
-
-#include <Arduino.h>
 #include <api/HardwareSerial.h>
 
 namespace arduino {
@@ -38,7 +36,7 @@ class ZephyrSerial : public HardwareSerial
 	template <int SZ>
 	class ZephyrSerialBuffer
 	{
-	      friend arduino::ZephyrSerial;
+		friend arduino::ZephyrSerial;
 		struct ring_buf ringbuf;
 		uint8_t buffer[SZ];
 		struct k_sem sem;
@@ -53,10 +51,15 @@ class ZephyrSerial : public HardwareSerial
 	ZephyrSerial(const struct device *dev) : uart(dev) { }
 	void begin(unsigned long baudrate, uint16_t config);
 	void begin(unsigned long baudrate) { begin(baudrate, SERIAL_8N1); }
-	void flush() { }
+	void flush() {
+		while (ring_buf_size_get(&tx.ringbuf) > 0) {
+			k_yield();
+		}
+	}
 	void end() { }
 	size_t write(const uint8_t *buffer, size_t size);
 	size_t write(const uint8_t data) { return write(&data, 1); }
+	using Print::write; // pull in write(str) and write(buf, size) from Print
 	int available();
 	int peek();
 	int read();
@@ -66,6 +69,8 @@ class ZephyrSerial : public HardwareSerial
 		return true;
 	}
 
+	friend class SerialUSB_;
+
 protected:
 	void IrqHandler();
 	static void IrqDispatch(const struct device *dev, void *data);
@@ -79,7 +84,10 @@ class ZephyrSerial : public HardwareSerial
 }   // namespace arduino
 
 #if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), serials)
+#if !DT_NODE_HAS_PROP(DT_PATH(zephyr_user), cdc_acm)
+// If CDC USB, use that object as Serial (and SerialUSB)
 extern arduino::ZephyrSerial Serial;
+#endif
 #if (DT_PROP_LEN(DT_PATH(zephyr_user), serials) > 1)
 #define SERIAL_DEFINED_0		 1
 #define EXTERN_SERIAL_N(i)		 extern arduino::ZephyrSerial Serial##i;