Fix Serial config

Fix stm32duino#50
Arduino defined several configs (data, parity and stop bits) values
for Serial.begin(speed, config)
See: https://www.arduino.cc/en/Serial/Begin
Below configs could not be supported by STM32 as minimum
wordlength (data + parity) is UART_WORDLENGTH_7B (7 bits).
SERIAL_5N1
SERIAL_5N2
SERIAL_5E1
SERIAL_5E2
SERIAL_5O1
SERIAL_5O2
SERIAL_6N1
SERIAL_6N2

Signed-off-by: Frederic Pillon <[email protected]>

Author: fpistm

Diff for: cores/arduino/HardwareSerial.cpp

@@ -26,6 +26,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <inttypes.h>
+#include <assert.h>
 #include "Arduino.h"
 #include "HardwareSerial.h"
 
@@ -83,15 +84,32 @@ int HardwareSerial::_tx_complete_irq(serial_t* obj)
 
 void HardwareSerial::begin(unsigned long baud, byte config)
 {
+  uint32_t databits = 0;
+
   _serial.baudrate = (uint32_t)baud;
 
-  // Could be 8 or 9 bits. Could match with Arduino small data length?
-  _serial.databits = UART_WORDLENGTH_8B;
+  // Manage databits
+  switch(config & 0x07) {
+    case 0x02:
+      databits = 6;
+      break;
+    case 0x04:
+      databits = 7;
+      break;
+    case 0x06:
+      databits = 8;
+      break;
+    default:
+      databits = 0;
+      break;
+  }
 
   if((config & 0x30) == 0x30) {
     _serial.parity = UART_PARITY_ODD;
+    databits++;
   } else if((config & 0x20) == 0x20) {
     _serial.parity = UART_PARITY_EVEN;
+    databits++;
   } else {
     _serial.parity = UART_PARITY_NONE;
   }
@@ -102,6 +120,25 @@ void HardwareSerial::begin(unsigned long baud, byte config)
     _serial.stopbits = UART_STOPBITS_1;
   }
 
+  switch(databits) {
+#ifdef UART_WORDLENGTH_7B
+    case 7:
+      _serial.databits = UART_WORDLENGTH_7B;
+      break;
+#endif
+    case 8:
+      _serial.databits = UART_WORDLENGTH_8B;
+      break;
+    case 9:
+      _serial.databits = UART_WORDLENGTH_9B;
+      break;
+    default:
+	case 0:
+      databits = 0;
+      break;
+  }
+  assert(databits!=0);
+
   uart_init(&_serial);
   uart_attach_rx_callback(&_serial, _rx_complete_irq);
 }

Diff for: cores/arduino/HardwareSerial.h

@@ -57,28 +57,32 @@ typedef uint8_t rx_buffer_index_t;
 #endif
 
 // Define config for Serial.begin(baud, config);
-#define SERIAL_5N1 0x00
-#define SERIAL_6N1 0x02
+// below configs are not supported by STM32
+//#define SERIAL_5N1 0x00
+//#define SERIAL_5N2 0x08
+//#define SERIAL_5E1 0x20
+//#define SERIAL_5E2 0x28
+//#define SERIAL_5O1 0x30
+//#define SERIAL_5O2 0x38
+//#define SERIAL_6N1 0x02
+//#define SERIAL_6N2 0x0A
+
+#ifdef UART_WORDLENGTH_7B
 #define SERIAL_7N1 0x04
-#define SERIAL_8N1 0x06
-#define SERIAL_5N2 0x08
-#define SERIAL_6N2 0x0A
 #define SERIAL_7N2 0x0C
-#define SERIAL_8N2 0x0E
-#define SERIAL_5E1 0x20
 #define SERIAL_6E1 0x22
+#define SERIAL_6E2 0x2A
+#define SERIAL_6O1 0x32
+#define SERIAL_6O2 0x3A
+#endif
+#define SERIAL_8N1 0x06
+#define SERIAL_8N2 0x0E
 #define SERIAL_7E1 0x24
 #define SERIAL_8E1 0x26
-#define SERIAL_5E2 0x28
-#define SERIAL_6E2 0x2A
 #define SERIAL_7E2 0x2C
 #define SERIAL_8E2 0x2E
-#define SERIAL_5O1 0x30
-#define SERIAL_6O1 0x32
 #define SERIAL_7O1 0x34
 #define SERIAL_8O1 0x36
-#define SERIAL_5O2 0x38
-#define SERIAL_6O2 0x3A
 #define SERIAL_7O2 0x3C
 #define SERIAL_8O2 0x3E