SoftI2C fork with ack fix
SoftI2C.cpp@0:fee70b6fe0e9, 2016-11-22 (annotated)
- Committer:
- Sissors
- Date:
- Tue Nov 22 20:45:35 2016 +0000
- Revision:
- 0:fee70b6fe0e9
- Child:
- 1:05473196d133
Initial version
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
Sissors | 0:fee70b6fe0e9 | 1 | #include "SoftI2C.h" |
Sissors | 0:fee70b6fe0e9 | 2 | |
Sissors | 0:fee70b6fe0e9 | 3 | SoftI2C::SoftI2C(PinName sda, PinName scl) : _sda(sda), _scl(scl) { |
Sissors | 0:fee70b6fe0e9 | 4 | // Set defaults |
Sissors | 0:fee70b6fe0e9 | 5 | _sda.mode(PullNone); |
Sissors | 0:fee70b6fe0e9 | 6 | _scl.mode(PullNone); |
Sissors | 0:fee70b6fe0e9 | 7 | _sda.input(); |
Sissors | 0:fee70b6fe0e9 | 8 | _scl.input(); |
Sissors | 0:fee70b6fe0e9 | 9 | frequency(100000); |
Sissors | 0:fee70b6fe0e9 | 10 | |
Sissors | 0:fee70b6fe0e9 | 11 | active = false; |
Sissors | 0:fee70b6fe0e9 | 12 | |
Sissors | 0:fee70b6fe0e9 | 13 | } |
Sissors | 0:fee70b6fe0e9 | 14 | |
Sissors | 0:fee70b6fe0e9 | 15 | void SoftI2C::frequency(int hz) { |
Sissors | 0:fee70b6fe0e9 | 16 | delay_us = 1000000 / hz / 4; //delay is a quarter of the total period |
Sissors | 0:fee70b6fe0e9 | 17 | } |
Sissors | 0:fee70b6fe0e9 | 18 | |
Sissors | 0:fee70b6fe0e9 | 19 | int SoftI2C::read(int address, char *data, int length, bool repeated) { |
Sissors | 0:fee70b6fe0e9 | 20 | start(); |
Sissors | 0:fee70b6fe0e9 | 21 | |
Sissors | 0:fee70b6fe0e9 | 22 | // Write address with LSB to one |
Sissors | 0:fee70b6fe0e9 | 23 | if (write(address | 0x01) == 0) { |
Sissors | 0:fee70b6fe0e9 | 24 | return 1; |
Sissors | 0:fee70b6fe0e9 | 25 | } |
Sissors | 0:fee70b6fe0e9 | 26 | |
Sissors | 0:fee70b6fe0e9 | 27 | // Read the data |
Sissors | 0:fee70b6fe0e9 | 28 | for(int i = 0; i<length - 1; i++) { |
Sissors | 0:fee70b6fe0e9 | 29 | data[i] = read(1); |
Sissors | 0:fee70b6fe0e9 | 30 | } |
Sissors | 0:fee70b6fe0e9 | 31 | data[length-1] = read(0); |
Sissors | 0:fee70b6fe0e9 | 32 | |
Sissors | 0:fee70b6fe0e9 | 33 | if (repeated == false) { |
Sissors | 0:fee70b6fe0e9 | 34 | stop(); |
Sissors | 0:fee70b6fe0e9 | 35 | } |
Sissors | 0:fee70b6fe0e9 | 36 | return 0; |
Sissors | 0:fee70b6fe0e9 | 37 | } |
Sissors | 0:fee70b6fe0e9 | 38 | |
Sissors | 0:fee70b6fe0e9 | 39 | int SoftI2C::write(int address, const char *data, int length, bool repeated) { |
Sissors | 0:fee70b6fe0e9 | 40 | start(); |
Sissors | 0:fee70b6fe0e9 | 41 | |
Sissors | 0:fee70b6fe0e9 | 42 | // Write address with LSB to zero |
Sissors | 0:fee70b6fe0e9 | 43 | if (write(address & 0xFE) == 0) { |
Sissors | 0:fee70b6fe0e9 | 44 | return 1; |
Sissors | 0:fee70b6fe0e9 | 45 | } |
Sissors | 0:fee70b6fe0e9 | 46 | |
Sissors | 0:fee70b6fe0e9 | 47 | // Write the data |
Sissors | 0:fee70b6fe0e9 | 48 | for(int i = 0; i<length; i++) { |
Sissors | 0:fee70b6fe0e9 | 49 | if(write(data[i]) == 0) { |
Sissors | 0:fee70b6fe0e9 | 50 | return 1; |
Sissors | 0:fee70b6fe0e9 | 51 | } |
Sissors | 0:fee70b6fe0e9 | 52 | } |
Sissors | 0:fee70b6fe0e9 | 53 | |
Sissors | 0:fee70b6fe0e9 | 54 | if (repeated == false) { |
Sissors | 0:fee70b6fe0e9 | 55 | stop(); |
Sissors | 0:fee70b6fe0e9 | 56 | } |
Sissors | 0:fee70b6fe0e9 | 57 | return 0; |
Sissors | 0:fee70b6fe0e9 | 58 | } |
Sissors | 0:fee70b6fe0e9 | 59 | |
Sissors | 0:fee70b6fe0e9 | 60 | int SoftI2C::read(int ack) { |
Sissors | 0:fee70b6fe0e9 | 61 | int retval = 0; |
Sissors | 0:fee70b6fe0e9 | 62 | |
Sissors | 0:fee70b6fe0e9 | 63 | // Shift the bits out, msb first |
Sissors | 0:fee70b6fe0e9 | 64 | for (int i = 7; i>=0; i--) { |
Sissors | 0:fee70b6fe0e9 | 65 | //SCL low |
Sissors | 0:fee70b6fe0e9 | 66 | _scl.output(); |
Sissors | 0:fee70b6fe0e9 | 67 | _scl.write(0); |
Sissors | 0:fee70b6fe0e9 | 68 | _sda.input(); |
Sissors | 0:fee70b6fe0e9 | 69 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 70 | |
Sissors | 0:fee70b6fe0e9 | 71 | //read SDA |
Sissors | 0:fee70b6fe0e9 | 72 | retval |= _sda.read() << i; |
Sissors | 0:fee70b6fe0e9 | 73 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 74 | |
Sissors | 0:fee70b6fe0e9 | 75 | //SCL high again |
Sissors | 0:fee70b6fe0e9 | 76 | _scl.input(); |
Sissors | 0:fee70b6fe0e9 | 77 | wait_us(delay_us << 1); //wait two delays |
Sissors | 0:fee70b6fe0e9 | 78 | } |
Sissors | 0:fee70b6fe0e9 | 79 | |
Sissors | 0:fee70b6fe0e9 | 80 | // Last cycle to set the ACK |
Sissors | 0:fee70b6fe0e9 | 81 | _scl.output(); |
Sissors | 0:fee70b6fe0e9 | 82 | _scl.write(0); |
Sissors | 0:fee70b6fe0e9 | 83 | if ( ack ) { |
Sissors | 0:fee70b6fe0e9 | 84 | _sda.output(); |
Sissors | 0:fee70b6fe0e9 | 85 | _sda.write(0); |
Sissors | 0:fee70b6fe0e9 | 86 | } else { |
Sissors | 0:fee70b6fe0e9 | 87 | _sda.input(); |
Sissors | 0:fee70b6fe0e9 | 88 | } |
Sissors | 0:fee70b6fe0e9 | 89 | wait_us(delay_us << 1); |
Sissors | 0:fee70b6fe0e9 | 90 | |
Sissors | 0:fee70b6fe0e9 | 91 | _scl.input(); |
Sissors | 0:fee70b6fe0e9 | 92 | wait_us(delay_us << 1); |
Sissors | 0:fee70b6fe0e9 | 93 | |
Sissors | 0:fee70b6fe0e9 | 94 | |
Sissors | 0:fee70b6fe0e9 | 95 | return retval; |
Sissors | 0:fee70b6fe0e9 | 96 | } |
Sissors | 0:fee70b6fe0e9 | 97 | |
Sissors | 0:fee70b6fe0e9 | 98 | int SoftI2C::write(int data) { |
Sissors | 0:fee70b6fe0e9 | 99 | // Shift the bits out, msb first |
Sissors | 0:fee70b6fe0e9 | 100 | for (int i = 7; i>=0; i--) { |
Sissors | 0:fee70b6fe0e9 | 101 | //SCL low |
Sissors | 0:fee70b6fe0e9 | 102 | _scl.output(); |
Sissors | 0:fee70b6fe0e9 | 103 | _scl.write(0); |
Sissors | 0:fee70b6fe0e9 | 104 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 105 | |
Sissors | 0:fee70b6fe0e9 | 106 | //Change SDA depending on the bit |
Sissors | 0:fee70b6fe0e9 | 107 | if ( (data >> i) & 0x01 ) { |
Sissors | 0:fee70b6fe0e9 | 108 | _sda.input(); |
Sissors | 0:fee70b6fe0e9 | 109 | } else { |
Sissors | 0:fee70b6fe0e9 | 110 | _sda.output(); |
Sissors | 0:fee70b6fe0e9 | 111 | _sda.write(0); |
Sissors | 0:fee70b6fe0e9 | 112 | } |
Sissors | 0:fee70b6fe0e9 | 113 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 114 | |
Sissors | 0:fee70b6fe0e9 | 115 | //SCL high again |
Sissors | 0:fee70b6fe0e9 | 116 | _scl.input(); |
Sissors | 0:fee70b6fe0e9 | 117 | wait_us(delay_us << 1); //wait two delays |
Sissors | 0:fee70b6fe0e9 | 118 | } |
Sissors | 0:fee70b6fe0e9 | 119 | |
Sissors | 0:fee70b6fe0e9 | 120 | // Last cycle to get the ACK |
Sissors | 0:fee70b6fe0e9 | 121 | _scl.output(); |
Sissors | 0:fee70b6fe0e9 | 122 | _scl.write(0); |
Sissors | 0:fee70b6fe0e9 | 123 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 124 | |
Sissors | 0:fee70b6fe0e9 | 125 | _sda.input(); |
Sissors | 0:fee70b6fe0e9 | 126 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 127 | |
Sissors | 0:fee70b6fe0e9 | 128 | _scl.input(); |
Sissors | 0:fee70b6fe0e9 | 129 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 130 | int retval = ~_sda.read(); //Read the ack |
Sissors | 0:fee70b6fe0e9 | 131 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 132 | |
Sissors | 0:fee70b6fe0e9 | 133 | return retval; |
Sissors | 0:fee70b6fe0e9 | 134 | } |
Sissors | 0:fee70b6fe0e9 | 135 | |
Sissors | 0:fee70b6fe0e9 | 136 | void SoftI2C::start(void) { |
Sissors | 0:fee70b6fe0e9 | 137 | if (active) { //if repeated start |
Sissors | 0:fee70b6fe0e9 | 138 | //Set SDA high, toggle scl |
Sissors | 0:fee70b6fe0e9 | 139 | _sda.input(); |
Sissors | 0:fee70b6fe0e9 | 140 | _scl.output(); |
Sissors | 0:fee70b6fe0e9 | 141 | _scl.write(0); |
Sissors | 0:fee70b6fe0e9 | 142 | wait_us(delay_us << 1); |
Sissors | 0:fee70b6fe0e9 | 143 | _scl.input(); |
Sissors | 0:fee70b6fe0e9 | 144 | wait_us(delay_us << 1); |
Sissors | 0:fee70b6fe0e9 | 145 | } |
Sissors | 0:fee70b6fe0e9 | 146 | // Pull SDA low |
Sissors | 0:fee70b6fe0e9 | 147 | _sda.output(); |
Sissors | 0:fee70b6fe0e9 | 148 | _sda.write(0); |
Sissors | 0:fee70b6fe0e9 | 149 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 150 | active = true; |
Sissors | 0:fee70b6fe0e9 | 151 | } |
Sissors | 0:fee70b6fe0e9 | 152 | |
Sissors | 0:fee70b6fe0e9 | 153 | void SoftI2C::stop(void) { |
Sissors | 0:fee70b6fe0e9 | 154 | // Float SDA high |
Sissors | 0:fee70b6fe0e9 | 155 | _scl.output(); |
Sissors | 0:fee70b6fe0e9 | 156 | _scl.write(0); |
Sissors | 0:fee70b6fe0e9 | 157 | _sda.output(); |
Sissors | 0:fee70b6fe0e9 | 158 | _sda.write(0); |
Sissors | 0:fee70b6fe0e9 | 159 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 160 | _scl.input(); |
Sissors | 0:fee70b6fe0e9 | 161 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 162 | _sda.input(); |
Sissors | 0:fee70b6fe0e9 | 163 | wait_us(delay_us); |
Sissors | 0:fee70b6fe0e9 | 164 | |
Sissors | 0:fee70b6fe0e9 | 165 | active = false; |
Sissors | 0:fee70b6fe0e9 | 166 | } |