| 89 | |
| 90 | |
| 91 | uint8_t PCF8591::analogRead(uint8_t channel, uint8_t mode) |
| 92 | { |
| 93 | if (mode > 3) |
| 94 | { |
| 95 | _error = PCF8591_MODE_ERROR; |
| 96 | return 0; |
| 97 | } |
| 98 | _control &= 0b01000100; // clear all except flags |
| 99 | _control |= (mode << 4); |
| 100 | |
| 101 | _error = PCF8591_CHANNEL_ERROR; |
| 102 | switch(mode) |
| 103 | { |
| 104 | case 0: |
| 105 | if (channel > 3) return 0; |
| 106 | _control |= channel; |
| 107 | break; |
| 108 | case 1: |
| 109 | if (channel > 2) return 0; |
| 110 | _control |= (channel << 4); |
| 111 | break; |
| 112 | case 2: |
| 113 | if (channel > 2) return 0; |
| 114 | _control |= (channel << 4); |
| 115 | break; |
| 116 | case 3: |
| 117 | if (channel > 1) return 0; |
| 118 | _control |= (channel << 4); |
| 119 | break; |
| 120 | default: |
| 121 | return 0; |
| 122 | } |
| 123 | _error = PCF8591_OK; |
| 124 | |
| 125 | // NOTE: one must read two values to get an up to date value. |
| 126 | // Page 8 datasheet. |
| 127 | _wire->beginTransmission(_address); |
| 128 | _wire->write(_control); |
| 129 | _error = _wire->endTransmission(); // default == 0 == PCF8591_OK |
| 130 | if (_error != 0) return PCF8591_I2C_ERROR; |
| 131 | |
| 132 | if (_wire->requestFrom(_address, (uint8_t)2) != 2) |
| 133 | { |
| 134 | _error = PCF8591_I2C_ERROR; |
| 135 | return _adc[channel]; // known last value |
| 136 | } |
| 137 | _wire->read(); |
| 138 | _adc[channel] = _wire->read(); |
| 139 | return _adc[channel]; |
| 140 | } |
| 141 | |
| 142 | |
| 143 | uint8_t PCF8591::analogRead4() |