add putchar to support printf

src/uart.c

@@ -0,0 +1,61 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <msp340g2553.h>
+
+#include "uart.h"
+#include "PontCoopScheduler.h"
+
+uint8_t txBuffer[UART_TX_BUFFER_SIZE+5];
+uint8_t txBufferReadIdx = 0;
+uint8_t txBufferWriteIdx = 0;
+
+
+void uartInit(void *handleArg) {
+  UCA0CTL1 |= UCSWRST;
+
+  P1SEL |= BIT1 | BIT2;
+  P1SEL2 |= BIT1 | BIT2;
+  UCA0CTL1 |= UCSSEL0; // ACLK
+  UCA0BR0 = 13;
+  UCA0BR1 = 0;
+  UCA0MCTL = UCBSR1 | UCBSR2;
+
+  UCA0CTL1 &= ~UCSWRST;
+}
+
+void uartExec(void *handleArg) {
+  if (txBufferReadIdx != txBufferWriteIdx) {
+    if ((IFG2 & UCA0TXIE) != 0) {
+      UCA0TXBUF = txBuffer[txBufferReadIdx];
+      txBufferReadIdx++;
+      if (txBufferReadIdx > UART_TX_BUFFER_SIZE) {
+	txBufferReadIdx = 0;
+      }
+    }
+  } else {
+    // stop transmitting
+    schDel(uartExec, NULL);
+  }
+}
+
+int putchar(int character) {
+  if (((txBufferWriteIdx == (UART_TX_BUFFER_SIZE - 1)) && (txBufferReadIdx == UART_TX_BUFFER_SIZE)) ||
+      ((txBufferWriteIdx != (UART_TX_BUFFER_SIZE - 1)) && (txBufferReadIdx == (txBufferWriteIdx + 1)))) {
+    return EOF;
+  }
+  txBuffer[txBufferWriteIdx] = (unsigned char)character;
+  txBufferWriteIdx++;
+
+  if (txBufferWriteIdx > UART_TX_BUFFER_SIZE) {
+    txBufferWriteIdx = 0;
+  }
+
+  // start transmitting
+  schAdd(uartExec, NULL, 0, 5);
+
+  return character;
+}
+  
+
+  
+  

src/uart.h

@@ -0,0 +1,14 @@
+#ifndef UART_H_
+#define UART_H_
+
+#include <stdint.h>
+
+
+#define UART_TX_BUFFER_SIZE 20
+
+
+void uartInit(void *handleArg);
+void uartExec(void *handleArg);
+int putchar(int character);
+
+#endif // UART_H_