The receive routine called by the interrupt handler
| 123 | // The receive routine called by the interrupt handler |
| 124 | // |
| 125 | void SoftwareSerial::recv() |
| 126 | { |
| 127 | |
| 128 | #if GCC_VERSION < 40302 |
| 129 | // Work-around for avr-gcc 4.3.0 OSX version bug |
| 130 | // Preserve the registers that the compiler misses |
| 131 | // (courtesy of Arduino forum user *etracer*) |
| 132 | asm volatile( |
| 133 | "push r18 \n\t" |
| 134 | "push r19 \n\t" |
| 135 | "push r20 \n\t" |
| 136 | "push r21 \n\t" |
| 137 | "push r22 \n\t" |
| 138 | "push r23 \n\t" |
| 139 | "push r26 \n\t" |
| 140 | "push r27 \n\t" |
| 141 | ::); |
| 142 | #endif |
| 143 | |
| 144 | uint8_t d = 0; |
| 145 | |
| 146 | // If RX line is high, then we don't see any start bit |
| 147 | // so interrupt is probably not for us |
| 148 | if (_inverse_logic ? rx_pin_read() : !rx_pin_read()) |
| 149 | { |
| 150 | // Disable further interrupts during reception, this prevents |
| 151 | // triggering another interrupt directly after we return, which can |
| 152 | // cause problems at higher baudrates. |
| 153 | setRxIntMsk(false); |
| 154 | |
| 155 | // Wait approximately 1/2 of a bit width to "center" the sample |
| 156 | tunedDelay(_rx_delay_centering); |
| 157 | DebugPulse(_DEBUG_PIN2, 1); |
| 158 | |
| 159 | // Read each of the 8 bits |
| 160 | for (uint8_t i=8; i > 0; --i) |
| 161 | { |
| 162 | tunedDelay(_rx_delay_intrabit); |
| 163 | d >>= 1; |
| 164 | DebugPulse(_DEBUG_PIN2, 1); |
| 165 | if (rx_pin_read()) |
| 166 | d |= 0x80; |
| 167 | } |
| 168 | |
| 169 | if (_inverse_logic) |
| 170 | d = ~d; |
| 171 | |
| 172 | // if buffer full, set the overflow flag and return |
| 173 | uint8_t next = (_receive_buffer_tail + 1) % _SS_MAX_RX_BUFF; |
| 174 | if (next != _receive_buffer_head) |
| 175 | { |
| 176 | // save new data in buffer: tail points to where byte goes |
| 177 | _receive_buffer[_receive_buffer_tail] = d; // save new byte |
| 178 | _receive_buffer_tail = next; |
| 179 | } |
| 180 | else |
| 181 | { |
| 182 | DebugPulse(_DEBUG_PIN1, 1); |
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