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- /*
- * twislave.c
- *
- * 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
- }
-
- 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];
- }
- dataSent = 0;
- }
-
- uint8_t twiDataWasSent(void) {
- if (dataSent != 0) {
- return 1;
- } else {
- return 0;
- }
- }
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