paul@0 | 1 | /* |
paul@0 | 2 | * Ben NanoNote I2C communication. |
paul@0 | 3 | * |
paul@0 | 4 | * Copyright (C) 2013 Paul Boddie |
paul@0 | 5 | * |
paul@0 | 6 | * This program is free software; you can redistribute it and/or modify |
paul@0 | 7 | * it under the terms of the GNU General Public License as published by |
paul@0 | 8 | * the Free Software Foundation; either version 2 of the License, or |
paul@0 | 9 | * (at your option) any later version. |
paul@0 | 10 | */ |
paul@0 | 11 | |
paul@0 | 12 | #include <time.h> |
paul@0 | 13 | #include "i2c.h" |
paul@0 | 14 | |
paul@0 | 15 | extern uint32_t I2C_SCL, I2C_SDA; |
paul@0 | 16 | |
paul@0 | 17 | void wait() |
paul@0 | 18 | { |
paul@0 | 19 | /* NOTE: Would want 600ns or 1300ns, but nanosleep appears too slow. |
paul@0 | 20 | struct timespec ts = {0, 600}; |
paul@0 | 21 | nanosleep(&ts, NULL); */ |
paul@0 | 22 | |
paul@0 | 23 | uint8_t i; |
paul@0 | 24 | for (i = 0; i < 200; i++); |
paul@0 | 25 | } |
paul@0 | 26 | |
paul@0 | 27 | /** |
paul@0 | 28 | * Declare the pins for initial I2C communications. |
paul@0 | 29 | */ |
paul@0 | 30 | void i2c_init() |
paul@0 | 31 | { |
paul@0 | 32 | OUT(I2C_SCL); |
paul@0 | 33 | OUT(I2C_SDA); |
paul@0 | 34 | } |
paul@0 | 35 | |
paul@0 | 36 | /** |
paul@0 | 37 | * Initiate an I2C transaction. |
paul@0 | 38 | */ |
paul@0 | 39 | void i2c_start() |
paul@0 | 40 | { |
paul@0 | 41 | OUT(I2C_SDA); |
paul@0 | 42 | CLR(I2C_SCL); |
paul@0 | 43 | wait(); |
paul@0 | 44 | SET(I2C_SDA); |
paul@0 | 45 | SET(I2C_SCL); |
paul@0 | 46 | wait(); |
paul@0 | 47 | CLR(I2C_SDA); |
paul@0 | 48 | } |
paul@0 | 49 | |
paul@0 | 50 | /** |
paul@0 | 51 | * Terminate an I2C transaction. |
paul@0 | 52 | */ |
paul@0 | 53 | void i2c_stop() |
paul@0 | 54 | { |
paul@0 | 55 | OUT(I2C_SDA); |
paul@0 | 56 | CLR(I2C_SCL); |
paul@0 | 57 | wait(); |
paul@0 | 58 | CLR(I2C_SDA); |
paul@0 | 59 | SET(I2C_SCL); |
paul@0 | 60 | wait(); |
paul@0 | 61 | SET(I2C_SDA); |
paul@0 | 62 | } |
paul@0 | 63 | |
paul@0 | 64 | /** |
paul@0 | 65 | * Send an I2C acknowledgement to a transmitting device. |
paul@0 | 66 | */ |
paul@0 | 67 | void i2c_ack(bool ack) |
paul@0 | 68 | { |
paul@0 | 69 | OUT(I2C_SDA); |
paul@0 | 70 | |
paul@0 | 71 | if (ack) |
paul@0 | 72 | CLR(I2C_SDA); |
paul@0 | 73 | else |
paul@0 | 74 | SET(I2C_SDA); |
paul@0 | 75 | |
paul@0 | 76 | SET(I2C_SCL); |
paul@0 | 77 | wait(); |
paul@0 | 78 | CLR(I2C_SCL); |
paul@0 | 79 | |
paul@0 | 80 | IN(I2C_SDA); |
paul@0 | 81 | } |
paul@0 | 82 | |
paul@0 | 83 | /** |
paul@0 | 84 | * Receive a single byte from an I2C device as part of a transaction. |
paul@0 | 85 | */ |
paul@0 | 86 | uint8_t i2c_recv() |
paul@0 | 87 | { |
paul@0 | 88 | uint8_t mask, result = 0; |
paul@0 | 89 | |
paul@0 | 90 | IN(I2C_SDA); |
paul@0 | 91 | CLR(I2C_SCL); |
paul@0 | 92 | |
paul@0 | 93 | for (mask = 0x80; mask; mask >>= 1) |
paul@0 | 94 | { |
paul@0 | 95 | SET(I2C_SCL); |
paul@0 | 96 | wait(); |
paul@0 | 97 | |
paul@0 | 98 | if (PIN(I2C_SDA)) |
paul@0 | 99 | result |= mask; |
paul@0 | 100 | |
paul@0 | 101 | CLR(I2C_SCL); |
paul@0 | 102 | wait(); |
paul@0 | 103 | } |
paul@0 | 104 | |
paul@0 | 105 | return result; |
paul@0 | 106 | } |
paul@0 | 107 | |
paul@0 | 108 | /** |
paul@0 | 109 | * Receive into a buffer a transmission of the given length in bytes. |
paul@0 | 110 | */ |
paul@0 | 111 | void i2c_recvmany(uint8_t *data, uint8_t len) |
paul@0 | 112 | { |
paul@0 | 113 | uint8_t *end = data + len; |
paul@0 | 114 | |
paul@0 | 115 | for (; data != end; data++, len--) |
paul@0 | 116 | { |
paul@0 | 117 | *data = i2c_recv(); |
paul@0 | 118 | i2c_ack(len > 1); |
paul@0 | 119 | } |
paul@0 | 120 | } |
paul@0 | 121 | |
paul@0 | 122 | void i2c_wait() |
paul@0 | 123 | { |
paul@0 | 124 | IN(I2C_SCL); |
paul@0 | 125 | while (!PIN(I2C_SCL)); |
paul@0 | 126 | OUT(I2C_SCL); |
paul@0 | 127 | } |
paul@0 | 128 | |
paul@0 | 129 | /** |
paul@0 | 130 | * Send a single byte of data to an I2C device as part of a transaction, |
paul@0 | 131 | * returning whether the transmission succeeded. |
paul@0 | 132 | */ |
paul@0 | 133 | bool i2c_send(uint8_t data) |
paul@0 | 134 | { |
paul@0 | 135 | uint8_t mask; |
paul@0 | 136 | bool status; |
paul@0 | 137 | |
paul@0 | 138 | OUT(I2C_SDA); |
paul@0 | 139 | CLR(I2C_SCL); |
paul@0 | 140 | |
paul@0 | 141 | for (mask = 0x80; mask; mask >>= 1) |
paul@0 | 142 | { |
paul@0 | 143 | wait(); |
paul@0 | 144 | |
paul@0 | 145 | if (data & mask) |
paul@0 | 146 | SET(I2C_SDA); |
paul@0 | 147 | else |
paul@0 | 148 | CLR(I2C_SDA); |
paul@0 | 149 | |
paul@0 | 150 | SET(I2C_SCL); |
paul@0 | 151 | wait(); |
paul@0 | 152 | CLR(I2C_SCL); |
paul@0 | 153 | } |
paul@0 | 154 | |
paul@0 | 155 | /* Wait for acknowledgement, failing if none is given. */ |
paul@0 | 156 | |
paul@0 | 157 | IN(I2C_SDA); |
paul@0 | 158 | SET(I2C_SCL); |
paul@0 | 159 | wait(); |
paul@0 | 160 | |
paul@0 | 161 | status = PIN(I2C_SDA); |
paul@0 | 162 | CLR(I2C_SCL); |
paul@0 | 163 | return !status; |
paul@0 | 164 | } |
paul@0 | 165 | |
paul@0 | 166 | /** |
paul@0 | 167 | * Send from the buffer provided a transmission with the given length to an I2C |
paul@0 | 168 | * device. |
paul@0 | 169 | */ |
paul@0 | 170 | bool i2c_sendmany(uint8_t *data, uint8_t len) |
paul@0 | 171 | { |
paul@0 | 172 | uint8_t *end = data + len; |
paul@0 | 173 | |
paul@0 | 174 | for (; data != end; data++) |
paul@0 | 175 | { |
paul@0 | 176 | if (!i2c_send(*data)) |
paul@0 | 177 | return false; |
paul@0 | 178 | |
paul@0 | 179 | /* NOTE: Should test for the slave holding the clock signal low. */ |
paul@0 | 180 | } |
paul@0 | 181 | |
paul@0 | 182 | return true; |
paul@0 | 183 | } |