arduino Serial is not thread safe

ESP32/main.ino

@@ -53,12 +53,6 @@
 
 constexpr const char SERIAL_CFG_FILE[] = "/serial.json";
 
-#if defined(BUILD_FOR_RP2040)
-#define Serial_RS232 Serial1
-#elif defined(TTY_SERIAL_RX)
-HardwareSerial       Serial_RS232(2);
-#endif
-
 bus     *b    = nullptr;
 cpu     *c    = nullptr;
 tty     *tty_ = nullptr;
@@ -78,7 +72,7 @@ bool                 trace_output    { false      };
 
 ntp                 *ntp_            { nullptr    };
 
-void console_thread_wrapper_panel(void *const c)
+static void console_thread_wrapper_panel(void *const c)
 {
 	console *const cnsl = reinterpret_cast<console *>(c);
 
@@ -213,17 +207,12 @@ void start_network(console *const c)
 		dc11 *dc11_ = new dc11(1100, b);
 
 #if !defined(BUILD_FOR_RP2040) && defined(TTY_SERIAL_RX)
-		constexpr uint32_t hwSerialConfig = SERIAL_8N1;
+		uint32_t bitrate = load_serial_speed_configuration();
-		uint32_t           bitrate        = load_serial_speed_configuration();
 
 		Serial.printf("* Init TTY (on DC11), baudrate: %d bps, RX: %d, TX: %d", bitrate, TTY_SERIAL_RX, TTY_SERIAL_TX);
 		Serial.println(F(""));
 
-		Serial_RS232.begin(bitrate, hwSerialConfig, TTY_SERIAL_RX, TTY_SERIAL_TX);
+		dc11_->set_serial(bitrate, TTY_SERIAL_RX, TTY_SERIAL_TX);
-		Serial_RS232.setHwFlowCtrlMode(0);
-		Serial_RS232.println(F("Go!"));
-
-		dc11_->set_serial(&Serial_RS232);
 #endif
 		b->add_DC11(dc11_);
 
@@ -244,16 +233,6 @@ void recall_configuration(console *const cnsl)
 }
 #endif
 
-#if defined(TTY_SERIAL_RX)
-void set_tty_serial_speed(console *const c, const uint32_t bps)
-{
-	Serial_RS232.begin(bps);
-
-	if (save_serial_speed_configuration(bps) == false)
-		c->put_string_lf("Failed to store configuration file with serial settings");
-}
-#endif
-
 #if defined(ESP32)
 void heap_caps_alloc_failed_hook(size_t requested_size, uint32_t caps, const char *function_name)
 {

dc11.cpp

@@ -8,6 +8,7 @@
 #include <lwip/sockets.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>
+#include <driver/uart.h>
 #elif defined(_WIN32)
 #include <ws2tcpip.h>
 #include <winsock2.h>
@@ -26,6 +27,8 @@
 #include "utils.h"
 
 
+#define ESP32_UART UART_NUM_1
+
 const char *const dc11_register_names[] { "RCSR", "RBUF", "TSCR", "TBUF" };
 
 bool setup_telnet_session(const int fd)
@@ -89,10 +92,7 @@ dc11::~dc11()
 	delete [] pfds;
 
 #if defined(ESP32)
-	if (serial_th) {
+	// won't work due to freertos thread
-		serial_th->join();
-		delete serial_th;
-	}
 #endif
 }
 
@@ -241,18 +241,47 @@ void dc11::operator()()
 }
 
 #if defined(ESP32)
-void dc11::set_serial(Stream *const s)
+void dc11_thread_wrapper_serial_handler(void *const c)
 {
-	if (serial_th) {
+        dc11 *const d = reinterpret_cast<dc11 *>(c);
+
+        d->serial_handler();
+
+        vTaskSuspend(nullptr);
+}
+
+void dc11::set_serial(const int bitrate, const int rx, const int tx)
+{
+	if (serial_thread_running) {
 		DOLOG(info, true, "DC11: serial port already configured");
 		return;
 	}
 
-	std::unique_lock<std::mutex> lck(s_lock);
+	serial_thread_running = true;
-	this->s = s;
-	s->write("Press enter to connect");
 
-	serial_th = new std::thread(&dc11::serial_handler, this);
+	// Configure UART parameters
+	static uart_config_t uart_config = {
+		.baud_rate = bitrate,
+		.data_bits = UART_DATA_8_BITS,
+		.parity    = UART_PARITY_DISABLE,
+		.stop_bits = UART_STOP_BITS_1,
+		.flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
+		.rx_flow_ctrl_thresh = 122,
+	};
+	ESP_ERROR_CHECK(uart_param_config(ESP32_UART, &uart_config));
+
+	ESP_ERROR_CHECK(uart_set_pin(ESP32_UART, tx, rx, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE));
+
+	// Setup UART buffered IO with event queue
+	const int uart_buffer_size = 1024 * 2;
+	static QueueHandle_t uart_queue;
+	// Install UART driver using an event queue here
+	ESP_ERROR_CHECK(uart_driver_install(ESP32_UART, uart_buffer_size, uart_buffer_size, 10, &uart_queue, 0));
+
+	const char msg[] = "Press enter to connect\r\n";
+	uart_write_bytes(ESP32_UART, msg, sizeof(msg) - 1);
+
+	xTaskCreate(&dc11_thread_wrapper_serial_handler, "dc11_tty", 3072, this, 1, nullptr);
 }
 
 void dc11::serial_handler()
@@ -260,15 +289,14 @@ void dc11::serial_handler()
 	while(!stop_flag) {
 		yield();
 
+		size_t n_available = 0;
+		ESP_ERROR_CHECK(uart_get_buffered_data_len(ESP32_UART, &n_available));
+		if (n_available == 0)
+			continue;
+
 		char c = 0;
-
+		if (uart_read_bytes(ESP32_UART, &c, 1, 100) == 0)
-		{
+			continue;
-			std::unique_lock<std::mutex> lck(s_lock);
-			if (s->available() == 0)
-				continue;
-
-			c = s->read();
-		}
 
 		// 3 is reserved for a serial port
 		constexpr const int serial_line = 3;
@@ -416,11 +444,8 @@ void dc11::write_word(const uint16_t addr, const uint16_t v)
 
 #if defined(ESP32)
 		if (line_nr == 3) {
-			if (s != nullptr) {
+			if (serial_thread_running)
-				std::unique_lock<std::mutex> lck(s_lock);
+				uart_write_bytes(ESP32_UART, &c, 1);
-
-				s->write(c);
-			}
 
 			if (is_tx_interrupt_enabled(line_nr))
 				trigger_interrupt(line_nr, true);

dc11.h

@@ -49,9 +49,7 @@ private:
 	std::vector<char> recv_buffers[dc11_n_lines];
         std::mutex        input_lock[dc11_n_lines];
 #if defined(ESP32)
-	std::mutex        s_lock;
+	std::atomic_bool  serial_thread_running { false };
-	Stream           *s                { nullptr };
-	std::thread      *serial_th        { nullptr };
 	bool              serial_enabled   { false   };
 #endif
 
@@ -70,7 +68,7 @@ public:
 
 	void reset();
 #if defined(ESP32)
-	void set_serial(Stream *const s);
+	void set_serial(const int bitrate, const int rx, const int tx);
 	void serial_handler();
 #endif
 

debugger.cpp

@@ -43,8 +43,6 @@
 void configure_network(console *const cnsl);
 void check_network(console *const cnsl);
 void start_network(console *const cnsl);
-
-void set_tty_serial_speed(console *const c, const uint32_t bps);
 #endif
 
 #if !defined(BUILD_FOR_RP2040) && !defined(linux) && !defined(_WIN32)
@@ -891,21 +889,6 @@ void debugger(console *const cnsl, bus *const b, std::atomic_uint32_t *const sto
 
 				continue;
 			}
-#if defined(CONSOLE_SERIAL_RX)
-			else if (parts.at(0) == "serspd") {
-				if (parts.size() == 2) {
-					uint32_t speed = std::stoi(parts.at(1), nullptr, 10);
-					set_tty_serial_speed(cnsl, speed);
-
-					cnsl->put_string_lf(format("Set baudrate to %d", speed));
-				}
-				else {
-					cnsl->put_string_lf("serspd requires an (decimal) parameter");
-				}
-
-				continue;
-			}
-#endif
 #endif
 			else if (cmd == "stats") {
 				show_run_statistics(cnsl, c);
@@ -1112,9 +1095,6 @@ void debugger(console *const cnsl, bus *const b, std::atomic_uint32_t *const sto
 					"cfgnet        - configure network (e.g. WiFi)",
 					"startnet      - start network",
 					"chknet        - check network status",
-#if defined(CONSOLE_SERIAL_RX)
-					"serspd x      - set serial speed in bps (8N1 are default)",
-#endif
 #endif
 					"cfgdisk       - configure disk",
 					"log ...       - log a message to the logfile",