| 1 | // pulseIn.c |
| 2 | // Reads pulse width on input GPIO pin |
| 3 | // Copyright (c) Joshua 'joshuas3' Stockin 2019 |
| 4 |
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| 5 | #include "driver/gpio.h" |
| 6 |
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| 7 | #define WAIT_FOR_PIN_STATE(state) \ |
| 8 | while (gpio_get_level(pin) != (state)) { \ |
| 9 | if (xthal_get_ccount() - func_start > 5000000) return 0; \ |
| 10 | } |
| 11 |
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| 12 | unsigned int pulseIn(unsigned char pin, unsigned char state) { |
| 13 | const unsigned int func_start = xthal_get_ccount(); |
| 14 | WAIT_FOR_PIN_STATE(!state); |
| 15 | WAIT_FOR_PIN_STATE(state); // wait until pin reaches state |
| 16 | const unsigned int pulse_start = xthal_get_ccount(); |
| 17 | WAIT_FOR_PIN_STATE(!state); // pin leaves state, record clock time elapsed |
| 18 | return xthal_get_ccount() - pulse_start; |
| 19 | } |
| 20 |
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