remove generic uart driver, integrate specialized uart handling into main

Makefile

@@ -5,7 +5,7 @@ MCU_TTY_BAUD   = 57600
 MCU_PROGRAMMER = arduino
 
 PRG            = main
-OBJ            = main.o uart.o
+OBJ            = main.o
 
 OPTIMIZE       = -O2
 DEFS           = -DF_CPU=$(MCU_FREQ) -DBAUDRATE=$(MCU_TTY_BAUD)

main.c

@@ -2,24 +2,14 @@
 #include <avr/io.h>
 #include <util/delay.h>
 #include <avr/interrupt.h>
-#include "uart.h"
+
+#define BAUD_PRESCALE (((F_CPU/(BAUDRATE*8UL)))-1)
 
 /* Button matrix between PB3-PB4, PC0-PC3
  * PC0-PC3 are inputs, default pull-up
  * PB3-PB4 are pulled to ground (alternating) while the above are read
  */
 
-void print_nibble(uint8_t nibble) {
-        nibble += 0x30;
-        if (nibble > 0x39) nibble += 7;
-        uart_putc(nibble);
-}
-
-void print_int8hex(uint8_t val) {
-        print_nibble(val >> 4);
-        print_nibble(val & 0x0F);
-}
-
 uint8_t getButtonState() {
         uint8_t val = 0;
 
@@ -79,6 +69,23 @@ void setrelay(uint8_t n, uint8_t s) {
 	}
 }
 
+char umode = 't';
+ISR(USART_RX_vect) {
+        uint8_t c = UDR0;
+	if (c == 't' || c == 'e' || c == 'd') {
+		umode = c;
+	} else if (c >= '0' && c <= '7') {
+		c = c - '0';
+		if (umode == 'e') {
+			setrelay(c,1);
+		} else if (umode == 'd') {
+			setrelay(c,0);
+		} else if (umode == 't') {
+			setrelay(c,1 - getrelay(c));
+		}
+	}
+}
+
 int main() {
 	DDRC &= ~(0b1111); // This sets PC0 to PC3 to input
 	PORTC |= 0b1111; // This makes dito pull-up per default
@@ -92,7 +99,16 @@ int main() {
 	PORTD |= 0b11111100;
 	PORTB |= 0b00000011;
 
+	// Init uart
+        UCSR0A = (1<<U2X0);
+	// Transmit is enabled to set PIN levels, but we will never write
+        UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0);
+        UCSR0C = (1<<UCSZ00) | (1<<UCSZ01); // 8N1
+        UBRR0 = BAUD_PRESCALE;
+
 	sei();
+
+	// Now handle button inputs
 	uint8_t c,p,d,i;
 	p = 0;
 
@@ -103,9 +119,6 @@ int main() {
 		for (i = 0; i<8; i++) {
 			if (d & c & 0x80) {
 				setrelay(i, 1 - getrelay(i));
-				print_nibble(i);
-				uart_putc('\r');
-				uart_putc('\n');
 			}
 			d = d << 1;
 			c = c << 1;

uart.c

@@ -1,82 +0,0 @@
-#include <avr/io.h>
-#include <avr/interrupt.h>
-#include <util/atomic.h>
-
-#include "uart.h"
-
-#define UART_BUFSIZE 64
-
-typedef volatile struct {
-	char data[UART_BUFSIZE];
-	uint8_t r;
-	uint8_t w;
-} buf;
-
-buf __attribute__ ((section (".noinit"))) uart_rxbuf;
-buf __attribute__ ((section (".noinit"))) uart_txbuf;
-
-#define BAUD_PRESCALE (((F_CPU/(BAUDRATE*8UL)))-1)
-
-void __attribute__ ((naked)) __attribute__ ((section (".init5"))) uart_init() {
-	uart_rxbuf.r = 0;
-	uart_rxbuf.w = 0;
-
-	uart_txbuf.r = 0;
-	uart_txbuf.w = 0;
-
-	UCSR0A = (1<<U2X0);
-	UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0);
-	UCSR0C = (1<<UCSZ00) | (1<<UCSZ01); // 8N1
-	UBRR0 = BAUD_PRESCALE;
-}
-
-void __attribute__ ((naked)) __attribute__ ((section (".fini5"))) uart_deinit() {
-	while ((UCSR0B & (1 << UDRIE0))) {};
-	while (!(UCSR0A & (1 << TXC0))) {};
-}
-
-// RX Facilities
-ISR(USART_RX_vect) {
-	uint8_t c = UDR0;
-
-	if (((uart_rxbuf.w - uart_rxbuf.r) & (UART_BUFSIZE - 1)) == 1) return;
-	uart_rxbuf.data[uart_rxbuf.w++] = c;
-	uart_rxbuf.w = uart_rxbuf.w & (UART_BUFSIZE - 1);
-}
-
-uint8_t uart_getc() {
-	uint8_t c;
-	while (uart_rxbuf.w == uart_rxbuf.r) {};
-
-	// Disable interrupt to avoid race condition
-	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
-		c = uart_rxbuf.data[uart_rxbuf.r++];
-		uart_rxbuf.r = uart_rxbuf.r & (UART_BUFSIZE - 1);
-	}
-
-	return c;
-}
-
-// TX Facilities
-ISR(USART_UDRE_vect) {
-	if ((uart_txbuf.w != uart_txbuf.r) && (UCSR0B & (1<<TXEN0))) {
-		UDR0 = uart_txbuf.data[uart_txbuf.r++];
-		uart_txbuf.r = uart_txbuf.r & (UART_BUFSIZE - 1);
-	} else {
-		UCSR0B &= ~(1<<UDRIE0); // UDRE off
-	}
-}
-
-uint8_t uart_putc(unsigned char c) {
-	while (((uart_txbuf.r - uart_txbuf.w) & (UART_BUFSIZE - 1)) == 1) {};
-
-	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
-		uart_txbuf.data[uart_txbuf.w++] = c;
-		uart_txbuf.w = uart_txbuf.w & (UART_BUFSIZE - 1);
-	}
-
-	UCSR0B |= (1<<UDRIE0); // UDRE on
-
-	return 1;
-}
-

uart.h

@@ -1,4 +0,0 @@
-#include <stdint.h>
-
-uint8_t uart_getc();
-uint8_t uart_putc(unsigned char c);