ESP32: add support for RS485 (#2559)

* ESP32: add support for RS485

This commit adds support for switching UART mode to RS485/IRDA.
Also included are patches for memory leaks then handling UART events other than data.

* ESP32: Documentation for uart.setmode()

components/base_nodemcu/uart.c

@@ -172,6 +172,20 @@ static int uart_setup( lua_State* L )
   return 1;
 }
 
+static int uart_setmode(lua_State* L)
+{
+	unsigned id, mode;
+	uint32_t res;
+	
+	id = luaL_checkinteger( L, 1 );
+	MOD_CHECK_ID( uart, id );
+	mode = luaL_checkinteger( L, 2 );
+	
+	platform_uart_setmode(id, mode);
+	
+	return 0;
+}
+
 // Lua: write( id, string1, [string2], ..., [stringn] )
 static int uart_write( lua_State* L )
 {
@@ -231,6 +245,7 @@ static const LUA_REG_TYPE uart_map[] =  {
   { LSTRKEY( "start" ), LFUNCVAL( uart_start ) },
   { LSTRKEY( "stop" ), LFUNCVAL( uart_stop ) },
   { LSTRKEY( "on" ),    LFUNCVAL( uart_on ) },
+  { LSTRKEY( "setmode" ), LFUNCVAL( uart_setmode ) },
   { LSTRKEY( "STOPBITS_1" ),   LNUMVAL( PLATFORM_UART_STOPBITS_1 ) },
   { LSTRKEY( "STOPBITS_1_5" ), LNUMVAL( PLATFORM_UART_STOPBITS_1_5 ) },
   { LSTRKEY( "STOPBITS_2" ),   LNUMVAL( PLATFORM_UART_STOPBITS_2 ) },
@@ -240,6 +255,11 @@ static const LUA_REG_TYPE uart_map[] =  {
   { LSTRKEY( "FLOWCTRL_NONE" ),   LNUMVAL( PLATFORM_UART_FLOW_NONE ) },
   { LSTRKEY( "FLOWCTRL_CTS" ),   LNUMVAL( PLATFORM_UART_FLOW_CTS ) },
   { LSTRKEY( "FLOWCTRL_RTS" ),   LNUMVAL( PLATFORM_UART_FLOW_RTS ) },
+  { LSTRKEY( "MODE_UART" ),   LNUMVAL( PLATFORM_UART_MODE_UART ) },
+  { LSTRKEY( "MODE_RS485_COLLISION_DETECT" ),   LNUMVAL( PLATFORM_UART_MODE_RS485_COLLISION_DETECT ) },
+  { LSTRKEY( "MODE_RS485_APP_CONTROL" ),   LNUMVAL( PLATFORM_UART_MODE_RS485_APP_CONTROL ) },
+  { LSTRKEY( "MODE_RS485_HALF_DUPLEX" ),   LNUMVAL( PLATFORM_UART_MODE_HALF_DUPLEX ) },
+  { LSTRKEY( "MODE_IRDA" ),   LNUMVAL( PLATFORM_UART_MODE_IRDA ) },
   { LNILKEY, LNILVAL }
 };
 

components/platform/include/platform.h

@@ -50,6 +50,15 @@ int platform_gpio_output_exists( unsigned gpio );
 
 #define UART_BUFFER_SIZE    512
 
+enum 
+{
+	PLATFORM_UART_MODE_UART = 0x0,
+	PLATFORM_UART_MODE_RS485_COLLISION_DETECT = 0x1,
+	PLATFORM_UART_MODE_RS485_APP_CONTROL = 0x2,
+	PLATFORM_UART_MODE_HALF_DUPLEX = 0x3,
+	PLATFORM_UART_MODE_IRDA = 0x4
+};
+
 // Parity
 enum
 {
@@ -107,6 +116,7 @@ typedef struct {
 // The platform UART functions
 static inline int platform_uart_exists( unsigned id ) { return id < NUM_UART; }
 uint32_t platform_uart_setup( unsigned id, uint32_t baud, int databits, int parity, int stopbits, uart_pins_t* pins );
+void platform_uart_setmode(unsigned id, unsigned mode);
 void platform_uart_send_multi( unsigned id, const char *data, size_t len );
 void platform_uart_send( unsigned id, uint8_t data );
 void platform_uart_flush( unsigned id );

components/platform/platform.c

@@ -76,7 +76,6 @@ void uart_event_task( task_param_t param, task_prio_t prio ) {
     }
     
     free(post->data);
-    free(post);
   } else {
     char *err;
     switch(post->type) {
@@ -92,6 +91,7 @@ void uart_event_task( task_param_t param, task_prio_t prio ) {
     }
     uart_on_error_cb(id, err, strlen(err));
   }
+  free(post);
 }
 
 static void task_uart( void *pvParameters ){
@@ -130,6 +130,7 @@ static void task_uart( void *pvParameters ){
           }
           post->id = id;
           post->type = PLATFORM_UART_EVENT_BREAK;
+		  break;
         case UART_FIFO_OVF:
         case UART_BUFFER_FULL:
         case UART_PARITY_ERR:
@@ -242,6 +243,26 @@ uint32_t platform_uart_setup( unsigned id, uint32_t baud, int databits, int pari
   }
 }
 
+void platform_uart_setmode(unsigned id, unsigned mode)
+{
+	uart_mode_t uartMode;
+	
+	switch(mode)
+	{
+		case PLATFORM_UART_MODE_IRDA:
+			uartMode = UART_MODE_IRDA; break;
+		case PLATFORM_UART_MODE_RS485_COLLISION_DETECT:
+			uartMode = UART_MODE_RS485_COLLISION_DETECT; break;
+		case PLATFORM_UART_MODE_RS485_APP_CONTROL:
+			uartMode = UART_MODE_RS485_APP_CTRL; break;
+		case PLATFORM_UART_MODE_HALF_DUPLEX:
+			uartMode = UART_MODE_RS485_HALF_DUPLEX; break;
+		case PLATFORM_UART_MODE_UART:
+		default:
+			uartMode = UART_MODE_UART; break;
+	}
+	uart_set_mode(id, uartMode);
+}
 
 void platform_uart_send_multi( unsigned id, const char *data, size_t len )
 {

docs/en/modules/uart.md

@@ -131,6 +131,26 @@ Stop the UART. You should not call `stop()` on the console uart.
 `nil`
 
 
+## uart.setmode()
+
+Set UART controllers communication mode
+
+#### Syntax
+
+`uart.setmode(id, mode)`
+
+#### Parameters
+- `id` uart id
+- `mode` value should be one of
+    - `uart.MODE_UART` default UART mode, is set after uart.setup() call
+    - `uart.MODE_RS485_COLLISION_DETECT` receiver must be always enabled, transmitter is automatically switched using RTS pin, collision is detected by UART hardware (note: no event is generated on collision, limitation of esp-idf)
+    - `uart.MODE_RS485_APP_CONTROL` receiver/transmitter control is left to the application
+    - `uart.MODE_RS485_HALF_DUPLEX` receiver/transmitter are controlled by RTS pin
+    - `uart.MODE_IRDA`
+    
+#### Returns
+`nil`
+
 ## uart.write()
 
 Write string or byte to the UART.