Rev 902 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
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| 771 | - | 1 | /**************************************************************************** |
| 1437 | - | 2 | * Copyright (C) 2009-2012 by Claas Anders "CaScAdE" Rathje * |
| 771 | - | 3 | * admiralcascade@gmail.com * |
| 4 | * Project-URL: http://www.mylifesucks.de/oss/c-strom/ * |
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| 5 | * * |
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| 6 | * This program is free software; you can redistribute it and/or modify * |
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| 7 | * it under the terms of the GNU General Public License as published by * |
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| 8 | * the Free Software Foundation; either version 2 of the License. * |
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| 9 | * * |
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| 10 | * This program is distributed in the hope that it will be useful, * |
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| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of * |
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| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
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| 13 | * GNU General Public License for more details. * |
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| 14 | * * |
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| 15 | * You should have received a copy of the GNU General Public License * |
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| 16 | * along with this program; if not, write to the * |
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| 17 | * Free Software Foundation, Inc., * |
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| 18 | * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * |
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| 19 | ****************************************************************************/ |
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| 20 | |||
| 21 | |||
| 22 | /**************************************************************************** |
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| 23 | * * |
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| 24 | * Most of the i²c/twi code is originally from * |
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| 25 | * http://www.rn-wissen.de/index.php/TWI_Slave_mit_avr-gcc * |
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| 26 | * * |
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| 27 | ****************************************************************************/ |
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| 28 | |||
| 29 | #include <avr/interrupt.h> |
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| 30 | #include <util/twi.h> |
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| 31 | #include "i2c_slave.h" |
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| 32 | #include "spi_union.h" |
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| 33 | |||
| 34 | void init_twi_slave(uint8_t address) { |
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| 35 | TWAR = address; |
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| 36 | TWCR &= ~(1 << TWSTA) | (1 << TWSTO); |
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| 37 | TWCR |= (1 << TWEA) | (1 << TWEN) | (1 << TWIE); |
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| 38 | i2c_buf_adr = 0xFF; |
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| 39 | //sei(); |
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| 40 | } |
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| 41 | |||
| 42 | ISR(TWI_vect) { |
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| 43 | uint8_t data = 0; |
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| 44 | //PORTD ^= (1 << PD7); // toggle LED for test |
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| 45 | switch (TW_STATUS) { |
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| 46 | case TW_SR_SLA_ACK: // 0x60 Slave Receiver, wurde adressiert |
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| 47 | TWCR_ACK; // next byte received |
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| 48 | i2c_buf_adr = 0xFF; // buf_adr undef |
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| 49 | break; |
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| 50 | case TW_SR_DATA_ACK: // 0x80 Slave Receiver,Daten empfangen |
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| 51 | data = TWDR; //Empfangene Daten auslesen |
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| 52 | if (i2c_buf_adr == 0xFF) {//erster Zugriff, Bufferposition setzen |
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| 53 | if (data <= I2C_BUFFER_SIZE) { //Kontrolle ob gewünschte Adresse im erlaubten bereich |
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| 54 | i2c_buf_adr = data; //Bufferposition wie adressiert setzen |
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| 55 | } else { |
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| 56 | i2c_buf_adr = 0; //Adresse auf Null setzen. Ist das sinnvoll? |
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| 57 | } |
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| 58 | TWCR_ACK; // nächstes Datenbyte empfangen, ACK danach, um nächstes Byte anzufordern |
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| 59 | } else {//weiterer Zugriff, Daten empfangen |
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| 60 | i2c_rx_buffer[i2c_buf_adr] = data; //Daten in Buffer schreiben |
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| 61 | i2c_buf_adr++; //Buffer-Adresse weiterzählen für nächsten Schreibzugriff |
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| 62 | if (i2c_buf_adr < (I2C_BUFFER_SIZE - 1)) {//im Buffer ist noch Platz für mehr als ein Byte |
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| 63 | TWCR_ACK; // nächstes Datenbyte empfangen, ACK danach, um nächstes Byte anzufordern |
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| 64 | } else {//es kann nur noch ein Byte kommen, dann ist der Buffer voll |
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| 65 | TWCR_NACK; //letztes Byte lesen, dann NACK, um vollen Buffer zu signaliseren |
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| 66 | } |
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| 67 | } |
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| 68 | break; |
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| 69 | case TW_ST_SLA_ACK: //?!? |
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| 70 | case TW_ST_DATA_ACK: //0xB8 Slave Transmitter, weitere Daten wurden angefordert |
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| 71 | if (i2c_buf_adr == 0xFF) {//zuvor keine Leseadresse angegeben! |
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| 72 | i2c_buf_adr = 0; |
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| 73 | } |
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| 74 | TWDR = i2c_tx_buffer[i2c_buf_adr]; //Datenbyte senden |
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| 75 | i2c_buf_adr++; //bufferadresse für nächstes Byte weiterzählen |
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| 76 | if (i2c_buf_adr < (I2C_BUFFER_SIZE - 1)) {//im Buffer ist mehr als ein Byte, das gesendet werden kann |
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| 77 | TWCR_ACK; //nächstes Byte senden, danach ACK erwarten |
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| 78 | } else { |
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| 79 | TWCR_NACK; //letztes Byte senden, danach NACK erwarten |
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| 80 | } |
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| 81 | break; |
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| 82 | case TW_ST_DATA_NACK: //0xC0 Keine Daten mehr gefordert |
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| 83 | case TW_SR_DATA_NACK: //0x88 |
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| 84 | case TW_ST_LAST_DATA: //0xC8 Last data byte in TWDR has been transmitted (TWEA = “0”); ACK has been received |
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| 85 | case TW_SR_STOP: // 0xA0 STOP empfangen |
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| 86 | default: |
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| 87 | TWCR_RESET; //Übertragung beenden, warten bis zur nächsten Adressierung |
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| 88 | break; |
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| 89 | } |
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| 90 | } |