Add 9bit support to HardwareSerial

Squash and rebase of arduino/Arduino#2291

Supersedes arduino/Arduino#1221

Author: Bouni

cores/arduino/HardwareSerial.cpp

@@ -82,10 +82,25 @@ void HardwareSerial::_tx_udr_empty_irq(void)
 {
   // If interrupts are enabled, there must be more data in the output
   // buffer. Send the next byte
-  unsigned char c = _tx_buffer[_tx_buffer_tail];
-  _tx_buffer_tail = (_tx_buffer_tail + 1) % SERIAL_TX_BUFFER_SIZE;
 
-  *_udr = c;
+  if(bit_is_set(*_ucsrb, UCSZ02)) {
+    // If Uart is configured for 9 bit mode
+    unsigned char mb = _tx_buffer[_tx_buffer_tail];
+    unsigned char c = _tx_buffer[_tx_buffer_tail + 1];
+    _tx_buffer_tail = (_tx_buffer_tail + 2) % SERIAL_TX_BUFFER_SIZE;
+    if(mb & 0x01) {
+      sbi(*_ucsrb, TXB80);
+    } else {
+      cbi(*_ucsrb, TXB80);
+    }
+    *_udr = c;
+  } else {
+    // UART is configured for 5 to 8 bit modes
+    unsigned char c = _tx_buffer[_tx_buffer_tail];
+    _tx_buffer_tail = (_tx_buffer_tail + 1) % SERIAL_TX_BUFFER_SIZE;
+
+    *_udr = c;
+  }
 
   // clear the TXC bit -- "can be cleared by writing a one to its bit
   // location". This makes sure flush() won't return until the bytes
@@ -100,7 +115,7 @@ void HardwareSerial::_tx_udr_empty_irq(void)
 
 // Public Methods //////////////////////////////////////////////////////////////
 
-void HardwareSerial::begin(unsigned long baud, byte config)
+void HardwareSerial::begin(unsigned long baud, uint16_t config)
 {
   // Try u2x mode first
   uint16_t baud_setting = (F_CPU / 4 / baud - 1) / 2;
@@ -127,8 +142,12 @@ void HardwareSerial::begin(unsigned long baud, byte config)
 #if defined(__AVR_ATmega8__)
   config |= 0x80; // select UCSRC register (shared with UBRRH)
 #endif
-  *_ucsrc = config;
-  
+
+  if(config & 0x100) {
+    sbi(*_ucsrb, UCSZ02);
+  }
+  *_ucsrc = (uint8_t) config;
+
   sbi(*_ucsrb, RXEN0);
   sbi(*_ucsrb, TXEN0);
   sbi(*_ucsrb, RXCIE0);
@@ -151,15 +170,28 @@ void HardwareSerial::end()
 
 int HardwareSerial::available(void)
 {
-  return ((unsigned int)(SERIAL_RX_BUFFER_SIZE + _rx_buffer_head - _rx_buffer_tail)) % SERIAL_RX_BUFFER_SIZE;
+  unsigned int a = (unsigned int) (SERIAL_RX_BUFFER_SIZE + _rx_buffer_head - _rx_buffer_tail) % SERIAL_RX_BUFFER_SIZE;
+  if(bit_is_set(*_ucsrb, UCSZ02)) {
+    // If Uart is in 9 bit mode return only the half, because we use two bytes per 9 bit "byte".
+    return a / 2;
+  }
+  else {
+    // For 5 - 8 bit modes simply return the number
+    return a;
+  }
 }
 
 int HardwareSerial::peek(void)
 {
   if (_rx_buffer_head == _rx_buffer_tail) {
     return -1;
   } else {
-    return _rx_buffer[_rx_buffer_tail];
+    if(bit_is_set(*_ucsrb, UCSZ02)) {
+      // If Uart is in 9 bit mode read two bytes and merge them
+      return (_rx_buffer[_rx_buffer_tail] << 8) | _rx_buffer[_rx_buffer_tail + 1 % SERIAL_RX_BUFFER_SIZE];
+    } else {
+      return _rx_buffer[_rx_buffer_tail];
+    }
   }
 }
 
@@ -169,9 +201,17 @@ int HardwareSerial::read(void)
   if (_rx_buffer_head == _rx_buffer_tail) {
     return -1;
   } else {
-    unsigned char c = _rx_buffer[_rx_buffer_tail];
-    _rx_buffer_tail = (rx_buffer_index_t)(_rx_buffer_tail + 1) % SERIAL_RX_BUFFER_SIZE;
-    return c;
+    if(bit_is_set(*_ucsrb, UCSZ02)) {
+      // If Uart is in 9 bit mode read two bytes and merge them
+      unsigned char mb = _rx_buffer[_rx_buffer_tail];
+      unsigned char c = _rx_buffer[_rx_buffer_tail + 1];
+      _rx_buffer_tail = (rx_buffer_index_t)(_rx_buffer_tail + 2) % SERIAL_RX_BUFFER_SIZE;
+      return ((mb << 8) | c);
+    } else {
+      unsigned char c = _rx_buffer[_rx_buffer_tail];
+      _rx_buffer_tail = (rx_buffer_index_t)(_rx_buffer_tail + 1) % SERIAL_RX_BUFFER_SIZE;
+      return c;
+    }
   }
 }
 
@@ -210,20 +250,35 @@ void HardwareSerial::flush()
   // the hardware finished tranmission (TXC is set).
 }
 
-size_t HardwareSerial::write(uint8_t c)
+size_t HardwareSerial::write(uint16_t c)
 {
   _written = true;
   // If the buffer and the data register is empty, just write the byte
   // to the data register and be done. This shortcut helps
   // significantly improve the effective datarate at high (>
   // 500kbit/s) bitrates, where interrupt overhead becomes a slowdown.
   if (_tx_buffer_head == _tx_buffer_tail && bit_is_set(*_ucsra, UDRE0)) {
-    *_udr = c;
+    if(bit_is_set(*_ucsrb, UCSZ02)) {
+      // in 9 bit mode set TXB8 bit if necessary
+      if(c & 0x100) {
+        sbi(*_ucsrb, TXB80);
+      } else {
+        cbi(*_ucsrb, TXB80);
+      }
+    }
+    *_udr = (uint8_t) c;
     sbi(*_ucsra, TXC0);
     return 1;
   }
-  tx_buffer_index_t i = (_tx_buffer_head + 1) % SERIAL_TX_BUFFER_SIZE;
-	
+
+  tx_buffer_index_t i;
+
+  if(bit_is_set(*_ucsrb, UCSZ02)) {
+    i = ((_tx_buffer_head + 2) % SERIAL_TX_BUFFER_SIZE);
+  } else {
+    i = ((_tx_buffer_head + 1) % SERIAL_TX_BUFFER_SIZE);
+  }
+
   // If the output buffer is full, there's nothing for it other than to 
   // wait for the interrupt handler to empty it a bit
   while (i == _tx_buffer_tail) {
@@ -239,7 +294,13 @@ size_t HardwareSerial::write(uint8_t c)
     }
   }
 
-  _tx_buffer[_tx_buffer_head] = c;
+
+  if(bit_is_set(*_ucsrb, UCSZ02)) {
+    _tx_buffer[_tx_buffer_head] = (uint8_t) (c >> 8) & 0x01;
+    _tx_buffer[_tx_buffer_head + 1] = (uint8_t) c;
+  } else {
+    _tx_buffer[_tx_buffer_head] = (uint8_t) c;
+  }
   _tx_buffer_head = i;
 
   sbi(*_ucsrb, UDRIE0);

cores/arduino/HardwareSerial.h

@@ -65,30 +65,41 @@ typedef uint8_t rx_buffer_index_t;
 #endif
 
 // Define config for Serial.begin(baud, config);
-#define SERIAL_5N1 0x00
-#define SERIAL_6N1 0x02
-#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_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
+#define SERIAL_5N1 0x000 //0b000000000
+#define SERIAL_6N1 0x002 //0b000000010
+#define SERIAL_7N1 0x004 //0b000000100
+#define SERIAL_8N1 0x006 //0b000000110
+#define SERIAL_9N1 0x106 //0b100000110
+
+#define SERIAL_5N2 0x008 //0b000001000
+#define SERIAL_6N2 0x00A //0b000001010
+#define SERIAL_7N2 0x00C //0b000001100
+#define SERIAL_8N2 0x00E //0b000001110
+#define SERIAL_9N2 0x10E //0b100001110
+
+#define SERIAL_5E1 0x020 //0b000100000
+#define SERIAL_6E1 0x022 //0b000100010
+#define SERIAL_7E1 0x024 //0b000100100
+#define SERIAL_8E1 0x026 //0b000100110
+#define SERIAL_9E1 0x126 //0b100100110
+
+#define SERIAL_5E2 0x028 //0b000101000
+#define SERIAL_6E2 0x02A //0b000101010
+#define SERIAL_7E2 0x02C //0b000101100
+#define SERIAL_8E2 0x02E //0b000101110
+#define SERIAL_9E2 0x12E //0b100101110
+
+#define SERIAL_5O1 0x030 //0b000110000
+#define SERIAL_6O1 0x032 //0b000110010
+#define SERIAL_7O1 0x034 //0b000110100
+#define SERIAL_8O1 0x036 //0b000110110
+#define SERIAL_9O1 0x136 //0b100110110
+
+#define SERIAL_5O2 0x038 //0b000111000
+#define SERIAL_6O2 0x03A //0b000111010
+#define SERIAL_7O2 0x03C //0b000111100
+#define SERIAL_8O2 0x03E //0b000111110
+#define SERIAL_9O2 0x13E //0b100111110
 
 class HardwareSerial : public Stream
 {
@@ -119,18 +130,18 @@ class HardwareSerial : public Stream
       volatile uint8_t *ucsra, volatile uint8_t *ucsrb,
       volatile uint8_t *ucsrc, volatile uint8_t *udr);
     void begin(unsigned long baud) { begin(baud, SERIAL_8N1); }
-    void begin(unsigned long, uint8_t);
+    void begin(unsigned long, uint16_t);
     void end();
     virtual int available(void);
     virtual int peek(void);
     virtual int read(void);
     virtual int availableForWrite(void);
     virtual void flush(void);
-    virtual size_t write(uint8_t);
-    inline size_t write(unsigned long n) { return write((uint8_t)n); }
-    inline size_t write(long n) { return write((uint8_t)n); }
-    inline size_t write(unsigned int n) { return write((uint8_t)n); }
-    inline size_t write(int n) { return write((uint8_t)n); }
+    virtual size_t write(uint16_t);
+    inline size_t write(unsigned long n) { return write((uint16_t)n); }
+    inline size_t write(long n) { return write((uint16_t)n); }
+    inline size_t write(unsigned int n) { return write((uint16_t)n); }
+    inline size_t write(int n) { return write((uint16_t)n); }
     using Print::write; // pull in write(str) and write(buf, size) from Print
     operator bool() { return true; }
 

cores/arduino/HardwareSerial_private.h

@@ -48,6 +48,9 @@
 #define U2X0 U2X
 #define UPE0 UPE
 #define UDRE0 UDRE
+#define UCSZ02 UCSZ2
+#define TXB80 TXB8
+#define RXB80 RXB8
 #elif defined(TXC1)
 // Some devices have uart1 but no uart0
 #define TXC0 TXC1
@@ -58,6 +61,9 @@
 #define U2X0 U2X1
 #define UPE0 UPE1
 #define UDRE0 UDRE1
+#define UCSZ02 UCSZ12
+#define TXB80 TXB81
+#define RXB80 RXB81
 #else
 #error No UART found in HardwareSerial.cpp
 #endif
@@ -68,17 +74,17 @@
 // changed for future hardware.
 #if defined(TXC1) && (TXC1 != TXC0 || RXEN1 != RXEN0 || RXCIE1 != RXCIE0 || \
 		      UDRIE1 != UDRIE0 || U2X1 != U2X0 || UPE1 != UPE0 || \
-		      UDRE1 != UDRE0)
+		      UDRE1 != UDRE0 || UCSZ12 != UCSZ02 || TXB81 != TXB80 || RXB81 != RXB80)
 #error "Not all bit positions for UART1 are the same as for UART0"
 #endif
 #if defined(TXC2) && (TXC2 != TXC0 || RXEN2 != RXEN0 || RXCIE2 != RXCIE0 || \
 		      UDRIE2 != UDRIE0 || U2X2 != U2X0 || UPE2 != UPE0 || \
-		      UDRE2 != UDRE0)
+		      UDRE2 != UDRE0 || UCSZ22 != UCSZ02 || TXB82 != TXB80 || RXB82 != RXB80)
 #error "Not all bit positions for UART2 are the same as for UART0"
 #endif
 #if defined(TXC3) && (TXC3 != TXC0 || RXEN3 != RXEN0 || RXCIE3 != RXCIE0 || \
 		      UDRIE3 != UDRIE0 || U3X3 != U3X0 || UPE3 != UPE0 || \
-		      UDRE3 != UDRE0)
+		      UDRE3 != UDRE0 || UCSZ32 != UCSZ02 || TXB83 != TXB80 || TXB83 != TXB80)
 #error "Not all bit positions for UART3 are the same as for UART0"
 #endif
 
@@ -103,15 +109,34 @@ void HardwareSerial::_rx_complete_irq(void)
   if (bit_is_clear(*_ucsra, UPE0)) {
     // No Parity error, read byte and store it in the buffer if there is
     // room
-    unsigned char c = *_udr;
-    rx_buffer_index_t i = (unsigned int)(_rx_buffer_head + 1) % SERIAL_RX_BUFFER_SIZE;
+    rx_buffer_index_t i;
+    unsigned char mb;
+    unsigned char c;
+
+    if(bit_is_set(*_ucsrb, UCSZ02)) {
+      // If Uart is configured for 9 bit mode
+      i = (unsigned int)(_rx_buffer_head + 2) % SERIAL_RX_BUFFER_SIZE;
+      mb = (*_ucsrb >> RXB80) & 0x01;
+      c = *_udr;
+    } else {
+      // UART is configured for 5 to 8 bit modes
+      i = (unsigned int)(_rx_buffer_head + 1) % SERIAL_RX_BUFFER_SIZE;
+      c = *_udr;
+    }
 
     // if we should be storing the received character into the location
     // just before the tail (meaning that the head would advance to the
     // current location of the tail), we're about to overflow the buffer
     // and so we don't write the character or advance the head.
     if (i != _rx_buffer_tail) {
-      _rx_buffer[_rx_buffer_head] = c;
+      if(bit_is_set(*_ucsrb, UCSZ02)) {
+        // If Uart is configured for 9 bit mode
+        _rx_buffer[_rx_buffer_head] = mb;
+        _rx_buffer[_rx_buffer_head + 1] = c;
+      } else {
+        // UART is configured for 5 to 8 bit modes
+        _rx_buffer[_rx_buffer_head] = c;
+      }
       _rx_buffer_head = i;
     }
   } else {