Added Audio TWI Slave functionality

AudioFirmware/main.c

@@ -27,6 +27,7 @@
 
 #include "adc.h"
 #include "eq.h"
+#include "twislave.h"
 
 #ifndef F_CPU
 #define F_CPU 16000000L
@@ -55,6 +56,7 @@ int main(void) {
 	DDRC = 0x0C;
 	DDRD = 0xFF;
 	
+	twiInit(0x42); // All TWI action happens completely in the background.
 	adcInit();
 	equalizerInit();
 

AudioFirmware/main.hex

@@ -1,86 +0,0 @@
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AudioFirmware/makefile

@@ -38,6 +38,7 @@ TARGET = main
 SRC = $(TARGET).c
 SRC += adc.c # Additional Source-File
 SRC += eq.c
+SRC += twislave.c
 
 # List Assembler source files here.
 # Make them always end in a capital .S.  Files ending in a lowercase .s

AudioFirmware/twislave.c

@@ -0,0 +1,92 @@
+/*
+ * twislave.h
+ *
+ * Copyright 2011 Thomas Buck <xythobuz@me.com>
+ * Copyright 2011 Max Nuding <max.nuding@gmail.com>
+ * Copyright 2011 Felix Bäder <baeder.felix@gmail.com>
+ *
+ * This file is part of LED-Cube.
+ *
+ * LED-Cube is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LED-Cube is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LED-Cube.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <stdint.h>
+
+uint8_t data[7] = { 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42 };
+uint8_t dataSent = 0;
+
+ISR(TWI_vect) {
+	static uint8_t dataPos = 0;
+	switch (TWSR & ~(7)) {
+		case 0xB0: case 0xA8: // We've been called
+			dataPos = 1; // Prepare next position
+			TWDR = data[0]; // Transmit first byte
+			TWCR |= (1 << TWEA); // More follows
+			dataSent = 0;
+			break;
+		case 0xB8: // We're doing fine
+			if (dataPos >= 6) {
+				// whoops, this shouldn't happen
+				// we transmit the last byte again and stop as if nothing happened
+				// we do this also if we reached the last byte
+				dataPos = 0;
+				TWDR = data[6];
+				TWCR &= ~(1 << TWEA); // Nothing follows
+				dataSent = 1;
+			} else {
+				TWDR = data[dataPos++]; // Transmit next byte
+				TWCR |= (1 << TWEA); // More follows
+				dataSent = 0;
+			}
+			break;
+		case 0xC0: case 0xC8: // We're done
+			TWCR |= (1 << TWEA);
+			dataSent = 1;
+			break;
+	}
+
+	TWCR |= (1 << TWINT); // Continue with bus operation
+}
+
+void twiInit(uint8_t address) {
+	if (address == 0) { // set slave address
+		TWAR = 1;
+	} else {
+		TWAR = address & ~(1);
+	}
+	TWCR = (1 << TWEN) | (1 << TWEA) | (1 << TWIE); // Enable twi, interrupt and acknowledge bit
+	
+	sei(); // Enable interrupts
+}
+
+void twiSetDataToSend(uint8_t *d) { // 7 bytes
+	// We don't care if it interrupts while we update the data.
+	// It will cause a single faulty frame. This will not be visible while showing many
+	// readouts in a short time.
+	uint8_t i;
+	for (i = 0; i < 7; i++) {
+		data[i] = d[i];
+	}
+}
+
+uint8_t twiDataWasSent() {
+	if (dataSent != 0) {
+		dataSent = 0;
+		return 1;
+	} else {
+		return 0;
+	}
+}

AudioFirmware/twislave.h

@@ -21,5 +21,6 @@
  * along with LED-Cube.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-void twiInit(uint8_t adress);
-void twiSetDataToSend(uint8_t *data);
+void twiInit(uint8_t address);
+void twiSetDataToSend(uint8_t *d); // 7 bytes
+uint8_t twiDataWasSent(void);