diff options
Diffstat (limited to 'platforms/avr/clockless_trinket.h')
| -rw-r--r-- | platforms/avr/clockless_trinket.h | 59 |
1 files changed, 51 insertions, 8 deletions
diff --git a/platforms/avr/clockless_trinket.h b/platforms/avr/clockless_trinket.h index f2dc14c9..5a9a96c6 100644 --- a/platforms/avr/clockless_trinket.h +++ b/platforms/avr/clockless_trinket.h @@ -63,6 +63,10 @@ template<> __attribute__((always_inline)) inline void _dc<10>(register uint8_t & // ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// +#if (!defined(NO_CORRECTION) || (NO_CORRECTION == 0)) && (FASTLED_ALLOW_INTERRUPTS == 0) +static uint8_t gTimeErrorAccum256ths; +#endif + template <uint8_t DATA_PIN, int T1, int T2, int T3, EOrder RGB_ORDER = RGB, int XTRA0 = 0, bool FLIP = false, int WAIT_TIME = 10> class ClocklessController : public CLEDController { typedef typename FastPin<DATA_PIN>::port_ptr_t data_ptr_t; @@ -105,14 +109,53 @@ protected: showRGBInternal(pixels); // Adjust the timer - #if (!defined(NO_CORRECTION) || (NO_CORRECTION == 0)) && (FASTLED_ALLOW_INTERRUPTS == 0) - uint32_t microsTaken = (uint32_t)nLeds * (uint32_t)CLKS_TO_MICROS(24 * (T1 + T2 + T3)); - if(microsTaken > 1024) { - MS_COUNTER += (microsTaken >> 10); - } else { - MS_COUNTER++; - } - #endif +#if (!defined(NO_CORRECTION) || (NO_CORRECTION == 0)) && (FASTLED_ALLOW_INTERRUPTS == 0) + uint32_t microsTaken = (uint32_t)nLeds * (uint32_t)CLKS_TO_MICROS(24 * (T1 + T2 + T3)); + + // adust for approximate observed actal runtime (as of January 2015) + // roughly 9.6 cycles per pixel, which is 0.6us/pixel at 16MHz + // microsTaken += nLeds * 0.6 * CLKS_TO_MICROS(16); + microsTaken += scale16by8(nLeds,(0.6 * 256) + 1) * CLKS_TO_MICROS(16); + + // if less than 1000us, there is NO timer impact, + // this is because the ONE interrupt that might come in while interrupts + // are disabled is queued up, and it will be serviced as soon as + // interrupts are re-enabled. + // This actually should technically also account for the runtime of the + // interrupt handler itself, but we're just not going to worry about that. + if( microsTaken > 1000) { + + // Since up to one timer tick will be queued, we don't need + // to adjust the MS_COUNTER for that one. + microsTaken -= 1000; + + // Now convert microseconds to 256ths of a second, approximately like this: + // 250ths = (us/4) + // 256ths = 250ths * (263/256); + uint16_t x256ths = microsTaken >> 2; + x256ths += scale16by8(x256ths,7); + + x256ths += gTimeErrorAccum256ths; + MS_COUNTER += (x256ths >> 8); + gTimeErrorAccum256ths = x256ths & 0xFF; + } + +#if 0 + // For pixel counts of 30 and under at 16Mhz, no correction is necessary. + // For pixel counts of 15 and under at 8Mhz, no correction is necessary. + // + // This code, below, is smaller, and quicker clock correction, which drifts much + // more significantly, but is a few bytes smaller. Presented here for consideration + // as an alternate on the ATtiny, which can't have more than about 150 pixels MAX + // anyway, meaning that microsTaken will never be more than about 4,500, which fits in + // a 16-bit variable. The difference between /1000 and /1024 only starts showing + // up in the range of about 100 pixels, so many ATtiny projects won't even + // see a clock difference due to the approximation there. + uint16_t microsTaken = (uint32_t)nLeds * (uint32_t)CLKS_TO_MICROS((24) * (T1 + T2 + T3)); + MS_COUNTER += (microsTaken >> 10); +#endif + +#endif sei(); mWait.mark(); |