Added support for UART break generation.

Author: Bogdan Marinescu

libraries/mbed/api/Serial.h

@@ -121,6 +121,10 @@ class Serial : public Stream {
         }
     }
 
+    /** Generate a break condition on the serial line
+     */
+    void send_break();
+
     static void _irq_handler(uint32_t id, SerialIrq irq_type);
 
 protected:
@@ -129,6 +133,7 @@ class Serial : public Stream {
 
     serial_t        _serial;
     FunctionPointer _irq[2];
+    int             _baud;
 };
 
 } // namespace mbed

libraries/mbed/common/Serial.cpp

@@ -14,18 +14,21 @@
  * limitations under the License.
  */
 #include "Serial.h"
+#include "wait_api.h"
 
 #if DEVICE_SERIAL
 
 namespace mbed {
 
 Serial::Serial(PinName tx, PinName rx, const char *name) : Stream(name) {
     serial_init(&_serial, tx, rx);
+    _baud = 9600;
     serial_irq_handler(&_serial, Serial::_irq_handler, (uint32_t)this);
 }
 
 void Serial::baud(int baudrate) {
     serial_baud(&_serial, baudrate);
+    _baud = baudrate;
 }
 
 void Serial::format(int bits, Parity parity, int stop_bits) {
@@ -65,6 +68,20 @@ int Serial::_putc(int c) {
     return c;
 }
 
+void Serial::send_break() {
+  // Wait for 1.5 frames before clearing the break condition
+  // This will have different effects on our platforms, but should
+  // ensure that we keep the break active for at least one frame.
+  // We consider a full frame (1 start bit + 8 data bits bits + 
+  // 1 parity bit + 2 stop bits = 12 bits) for computation.
+  // One bit time (in us) = 1000000/_baud
+  // Twelve bits: 12000000/baud delay
+  // 1.5 frames: 18000000/baud delay
+  serial_break_set(&_serial);
+  wait_us(18000000/_baud);
+  serial_break_clear(&_serial);
+}
+
 } // namespace mbed
 
 #endif

libraries/mbed/hal/serial_api.h

@@ -55,6 +55,9 @@ int  serial_readable   (serial_t *obj);
 int  serial_writable   (serial_t *obj);
 void serial_clear      (serial_t *obj);
 
+void serial_break_set  (serial_t *obj);
+void serial_break_clear(serial_t *obj);
+
 void serial_pinout_tx(PinName tx);
 
 #ifdef __cplusplus

libraries/mbed/targets/hal/TARGET_Freescale/TARGET_KL05Z/serial_api.c

@@ -277,3 +277,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
     pinmap_pinout(tx, PinMap_UART_TX);
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->C2 |= UART0_C2_SBK_MASK; 
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->C2 &= ~UART0_C2_SBK_MASK;
+}
+

libraries/mbed/targets/hal/TARGET_Freescale/TARGET_KL25Z/serial_api.c

@@ -294,3 +294,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
     pinmap_pinout(tx, PinMap_UART_TX);
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->C2 |= UART_C2_SBK_MASK; 
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->C2 &= ~UART_C2_SBK_MASK;
+}
+

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/serial_api.c

@@ -271,3 +271,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
     pinmap_pinout(tx, PinMap_UART_TX);
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->LCR |= (1 << 6);
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->LCR &= ~(1 << 6);
+}
+

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC13XX/serial_api.c

@@ -271,3 +271,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
     pinmap_pinout(tx, PinMap_UART_TX);
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->LCR |= (1 << 6);
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->LCR &= ~(1 << 6);
+}
+

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/serial_api.c

@@ -307,3 +307,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
     pinmap_pinout(tx, PinMap_UART_TX);
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->LCR |= (1 << 6);
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->LCR &= ~(1 << 6);
+}
+

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC23XX/serial_api.c

@@ -307,3 +307,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
     pinmap_pinout(tx, PinMap_UART_TX);
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->LCR |= (1 << 6);
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->LCR &= ~(1 << 6);
+}
+

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/serial_api.c

@@ -300,3 +300,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
     pinmap_pinout(tx, PinMap_UART_TX);
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->LCR |= (1 << 6);
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->LCR &= ~(1 << 6);
+}
+

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC43XX/serial_api.c

@@ -281,3 +281,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
     pinmap_pinout(tx, PinMap_UART_TX);
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->LCR |= (1 << 6);
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->LCR &= ~(1 << 6);
+}
+

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC81X/serial_api.c

@@ -59,6 +59,8 @@ static int get_available_uart(void) {
 #define RXRDY         (0x01<<0)
 #define TXRDY         (0x01<<2)
 
+#define TXBRKEN       (0x01<<1)
+
 static uint32_t UARTSysClk;
 
 static uint32_t serial_irq_ids[UART_NUM] = {0};
@@ -267,3 +269,12 @@ void serial_clear(serial_t *obj) {
 void serial_pinout_tx(PinName tx) {
 
 }
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->CTRL |= TXBRKEN;
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->CTRL &= ~TXBRKEN;
+}
+