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work around for first bit glitching

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forcing the pin low seems to fix the first bit having glitches in width.
This commit is contained in:
Makuna
2015-05-02 15:23:57 -07:00
parent 880552a4d9
commit d2c4b417a5
1 changed files with 25 additions and 14 deletions
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39
NeoPixelBus.cpp
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@@ -76,16 +76,16 @@ void NeoPixelBus::Begin(void)
#if defined(ESP8266) #if defined(ESP8266)
#define CYCLES_800_T0H (F_CPU / 2500000 - 2) // 0.4us #define CYCLES_800_T0H (F_CPU / 2500000 - 4) // 0.4us
#define CYCLES_800_T1H (F_CPU / 1250000 - 2) // 0.8us #define CYCLES_800_T1H (F_CPU / 1250000 - 4) // 0.8us
#define CYCLES_800 (F_CPU / 800000 - 2) // 1.25us per bit #define CYCLES_800 (F_CPU / 800000 - 4) // 1.25us per bit
#define CYCLES_400_T0H (F_CPU / 2000000 - 2) #define CYCLES_400_T0H (F_CPU / 2000000 - 4)
#define CYCLES_400_T1H (F_CPU / 833333 - 2) #define CYCLES_400_T1H (F_CPU / 833333 - 4)
#define CYCLES_400 (F_CPU / 400000 - 2) #define CYCLES_400 (F_CPU / 400000 - 4)
#define RSR_CCOUNT(r) __asm__ __volatile__("rsr %0,234":"=a" (r)) #define RSR_CCOUNT(r) __asm__ __volatile__("rsr %0,234":"=a" (r))
static inline ICACHE_FLASH_ATTR uint32_t get_ccount(void) static inline uint32_t get_ccount(void)
{ {
uint32_t ccount; uint32_t ccount;
RSR_CCOUNT(ccount); RSR_CCOUNT(ccount);
@@ -93,33 +93,40 @@ static inline ICACHE_FLASH_ATTR uint32_t get_ccount(void)
} }
static inline void ICACHE_FLASH_ATTR send_pixels_800(uint8_t* pixels, uint8_t* end, uint8_t pin) static inline void send_pixels_800(uint8_t* pixels, uint8_t* end, uint8_t pin)
{ {
const uint32_t pinRegister = _BV(pin); const uint32_t pinRegister = _BV(pin);
uint32_t mask; // 32 bit work is optimized for the chip uint8_t mask;
uint32_t subpix; // 32 bit work is optimized for the chip uint8_t subpix;
uint32_t cyclesStart; uint32_t cyclesStart;
// do not remove, this cleans up the initial bit
// set so that it is more stable
GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, pinRegister);
cyclesStart = get_ccount() + CYCLES_800; cyclesStart = get_ccount() + CYCLES_800;
while (pixels < end) while (pixels < end)
{ {
subpix = *pixels++; subpix = *pixels++;
for (mask = 0x80; mask; mask >>= 1) for (mask = 0x80; mask; mask >>= 1)
{ {
uint32_t nextBit = (subpix & mask); // do the check here while we are waiting on time to pass
bool nextBit = (subpix & mask);
uint32_t cyclesNext = cyclesStart; uint32_t cyclesNext = cyclesStart;
// after we have done as much work as needed for this next bit // after we have done as much work as needed for this next bit
// now wait for the HIGH // now wait for the HIGH
do do
{ {
// cache and use this count so we don't incur another
// instruction before we turn the bit high
cyclesStart = get_ccount(); cyclesStart = get_ccount();
} }
while ((cyclesStart - cyclesNext) < CYCLES_800); while ((cyclesStart - cyclesNext) < CYCLES_800);
// set high
GPIO_REG_WRITE(GPIO_OUT_W1TS_ADDRESS, pinRegister); GPIO_REG_WRITE(GPIO_OUT_W1TS_ADDRESS, pinRegister);
// wait for the LOW // wait for the LOW
if (nextBit) if (nextBit)
{ {
@@ -130,6 +137,7 @@ static inline void ICACHE_FLASH_ATTR send_pixels_800(uint8_t* pixels, uint8_t* e
while ((get_ccount() - cyclesStart) < CYCLES_800_T0H); while ((get_ccount() - cyclesStart) < CYCLES_800_T0H);
} }
// set low
GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, pinRegister); GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, pinRegister);
} }
} }
@@ -199,7 +207,10 @@ void NeoPixelBus::Show(void)
// subsequent round of data until the latch time has elapsed. This // subsequent round of data until the latch time has elapsed. This
// allows the mainline code to start generating the next frame of data // allows the mainline code to start generating the next frame of data
// rather than stalling for the latch. // rather than stalling for the latch.
while ((micros() - _endTime) < 50L); while ((micros() - _endTime) < 50L)
{
delayMicroseconds(1);
}
// _endTime is a private member (rather than global var) so that mutliple // _endTime is a private member (rather than global var) so that mutliple
// instances on different pins can be quickly issued in succession (each // instances on different pins can be quickly issued in succession (each
// instance doesn't delay the next). // instance doesn't delay the next).