251209_uart

recv/pixmod_recv_1v0/main.c

@@ -100,3 +100,57 @@ void setPixelColor(uint8_t n, uint8_t r, uint8_t g, uint8_t b) {
 
 
 
+int uart_putchar(char c, FILE *stream);
+
+void uart_init(void) {
+    UART_TX_DDR |= (1 << UART_TX_PIN); // set to output
+    
+    UART_TX_PORT |= (1 << UART_TX_PIN); // set to HIGH - idle state in UART
+
+    fdevopen(uart_putchar, NULL);
+}
+
+void uart_transmit(uint8_t data) {
+    uint8_t i;
+    
+    UART_TX_PORT &= ~(1 << UART_TX_PIN); // LOW for start bit
+    _delay_us(UART_BIT_DELAY_US);
+
+    // send 8 bits LSB
+    for (i = 0; i < 8; i++) {
+        if (data & (1 << i)) {
+            UART_TX_PORT |= (1 << UART_TX_PIN); // set high
+        } else {
+            UART_TX_PORT &= ~(1 << UART_TX_PIN); // set low
+        }
+        
+        _delay_us(UART_BIT_DELAY_US); 
+    }
+
+    UART_TX_PORT |= (1 << UART_TX_PIN); // high for stop bit
+    _delay_us(UART_BIT_DELAY_US); 
+}
+
+void uart_print_str(const char* str) {
+    while (*str) {
+        uart_transmit(*str++);
+    }
+}
+
+int uart_putchar(char c, FILE *stream) {
+    uint8_t sreg = SREG;
+    cli();
+
+    if (c == '\n') {
+        uart_transmit('\r');
+    }
+    uart_transmit(c);
+
+    SREG = sreg;
+    sei();
+
+    return 0;
+}
+
+
+