1 | /*##############################################################################
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2 | Name : USI TWI Slave driver - I2C/TWI-EEPROM
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3 | Version : 1.3 - Stable
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4 | autor : Martin Junghans jtronics@gmx.de
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5 | page : www.jtronics.de
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6 | License : GNU General Public License
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7 |
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8 | Created from Atmel source files for Application Note AVR312:
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9 | Using the USI Module as an I2C slave like a I2C-EEPROM.
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10 | //############################################################################*/
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11 |
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12 | #include <stdlib.h>
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13 | #include <avr/io.h>
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14 | #include <avr/interrupt.h>
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15 | #include <avr/pgmspace.h>
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16 |
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17 | //################################################################## USI-TWI-I2C
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18 |
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19 | #include "usiTwiSlave.h"
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20 |
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21 | // Note: The LSB is the I2C r/w flag and must not be used for addressing!
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22 | #define SLAVE_ADDR_ATTINY 0x52 // 0b00110100
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23 |
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24 | #ifndef F_CPU
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25 | #define F_CPU 16000000UL
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26 | #endif
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27 |
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28 | //####################################################################### Macros
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29 |
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30 | #define uniq(LOW,HEIGHT) ((HEIGHT << 8)|LOW) // Create 16 bit number from two bytes
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31 | #define LOW_BYTE(x) (x & 0xff) // Get low byte from 16 bit number
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32 | #define HIGH_BYTE(x) ((x >> 8) & 0xff) // Get high byte from 16 bit number
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33 |
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34 | #define sbi(ADDRESS,BIT) ((ADDRESS) |= (1<<(BIT))) // Set bit
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35 | #define cbi(ADDRESS,BIT) ((ADDRESS) &= ~(1<<(BIT)))// Clear bit
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36 | #define toggle(ADDRESS,BIT) ((ADDRESS) ^= (1<<BIT)) // Toggle bit
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37 |
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38 | #define bis(ADDRESS,BIT) (ADDRESS & (1<<BIT)) // Is bit set?
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39 | #define bic(ADDRESS,BIT) (!(ADDRESS & (1<<BIT))) // Is bit clear?
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40 |
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41 | //#################################################################### Variables
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42 |
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43 | uint16_t word=0; // Counter
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44 | uint8_t byte1, byte2;
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45 | uint16_t buffer;
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46 | uint8_t high,low = 0; // Variables used with uniq (high and low byte)
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47 |
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48 | //################################################################# Main routine
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49 | int main(void)
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50 | {
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51 | cli(); // Disable interrupts
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52 |
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53 | usiTwiSlaveInit(SLAVE_ADDR_ATTINY); // TWI slave init
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54 |
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55 | sei(); // Re-enable interrupts
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56 |
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57 | for (int i = 0; i < 10; i++) // Fill buffers with arbitrary data
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58 | txbuffer[i] = i + 10;
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59 |
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60 | for (int i = 0; i < 4; i++)
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61 | rxbuffer[i] = i + 20;
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62 |
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63 | while(1)
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64 | {
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65 | //############################################ Read data from reception buffer
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66 | // 8 bit variables
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67 | byte1 = rxbuffer[0];
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68 | byte2 = rxbuffer[1];
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69 |
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70 | // 2 8 bit variables converted into a 16 bit number
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71 | low = rxbuffer[2];
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72 | high = rxbuffer[3];
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73 | word = uniq(low,high);
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74 |
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75 | //########################################## Write data to transmission buffer
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76 | // 8 bit variables
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77 | txbuffer[0]= byte1;
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78 | txbuffer[1]= byte2;
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79 |
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80 | // 16 bit variable broken up into its high and low byte
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81 | buffer = word;
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82 | txbuffer[2] = LOW_BYTE(buffer);
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83 | txbuffer[3] = HIGH_BYTE(buffer);
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84 |
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85 | //############################################################################
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86 |
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87 | } //end.while
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88 | } //end.main
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