diff options
Diffstat (limited to 'cores/arduino')
| -rw-r--r-- | cores/arduino/wiring_pulse.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/cores/arduino/wiring_pulse.c b/cores/arduino/wiring_pulse.c index 0d96886..830c454 100644 --- a/cores/arduino/wiring_pulse.c +++ b/cores/arduino/wiring_pulse.c @@ -61,9 +61,25 @@ unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout) width++; } - // convert the reading to microseconds. The loop has been determined - // to be 20 clock cycles long and have about 16 clocks between the edge - // and the start of the loop. There will be some error introduced by + // convert the reading to microseconds. There will be some error introduced by // the interrupt handlers. - return clockCyclesToMicroseconds(width * 21 + 16); + + // Conversion constants are compiler-dependent, different compiler versions + // have different levels of optimization. +#if __GNUC__==4 && __GNUC_MINOR__==3 && __GNUC_PATCHLEVEL__==2 + // avr-gcc 4.3.2 + return clockCyclesToMicroseconds(width * 21 + 16); +#elif __GNUC__==4 && __GNUC_MINOR__==8 && __GNUC_PATCHLEVEL__==1 + // avr-gcc 4.8.1 + return clockCyclesToMicroseconds(width * 24 + 16); +#elif __GNUC__<=4 && __GNUC_MINOR__<=3 + // avr-gcc <=4.3.x + #warning "pulseIn() results may not be accurate" + return clockCyclesToMicroseconds(width * 21 + 16); +#else + // avr-gcc >4.3.x + #warning "pulseIn() results may not be accurate" + return clockCyclesToMicroseconds(width * 24 + 16); +#endif + } |