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Green pixel fix #110

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merged 1 commit into from
Jan 28, 2016
Merged

Green pixel fix #110

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196 changes: 73 additions & 123 deletions libraries/Adafruit_NeoPixel/Adafruit_NeoPixel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1021,143 +1021,93 @@ void Adafruit_NeoPixel::show(void) {

// Arduino 101 -----------------------------------------------------------

PinDescription *pindesc = &g_APinDescription[pin];
uint8_t *p = pixels, *end = p + numBytes;
register uint8_t pix, mask;
#define NOPx7{ __builtin_arc_nop(); \
__builtin_arc_nop(); __builtin_arc_nop(); \
__builtin_arc_nop(); __builtin_arc_nop(); \
__builtin_arc_nop(); __builtin_arc_nop(); }

PinDescription *pindesc = &g_APinDescription[pin];
register uint32_t loop = 8 * numBytes; // one loop to handle all bytes and all bits
register uint8_t *p = pixels;
register uint32_t currByte = (uint32_t) (*p);
register uint32_t currBit = 0x80 & currByte;
register uint32_t bitCounter = 0;
register uint32_t first = 1;

// The loop is unusual. Very first iteration puts all the way LOW to the wire -
// constant LOW does not affect NEOPIXEL, so there is no visible effect displayed.
// During that very first iteration CPU caches instructions in the loop.
// Because of the caching process, "CPU slows down". NEOPIXEL pulse is very time sensitive
// that's why we let the CPU cache first and we start regular pulse from 2nd iteration
if (pindesc->ulGPIOType == SS_GPIO) {
register uint32_t reg = pindesc->ulGPIOBase + SS_GPIO_SWPORTA_DR;
register uint32_t reg_val = __builtin_arc_lr((volatile uint32_t)reg);
uint32_t reg_val = __builtin_arc_lr((volatile uint32_t)reg);
register uint32_t reg_bit_high = reg_val | (1 << pindesc->ulGPIOId);
register uint32_t reg_bit_low = reg_val & ~(1 << pindesc->ulGPIOId);

while(p < end) {
pix = *p++;
for(mask = 0x80; mask; mask >>= 1) {
__builtin_arc_sr(reg_bit_high, (volatile uint32_t)reg);
if(pix & mask) {
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_sr(reg_bit_low, (volatile uint32_t)reg);
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
} else {
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_sr(reg_bit_low, (volatile uint32_t)reg);
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
}
loop += 1; // include first, special iteration
while(loop--) {
if(!first) {
currByte <<= 1;
bitCounter++;
}

// 1 is >550ns high and >450ns low; 0 is 200..500ns high and >450ns low
__builtin_arc_sr(first ? reg_bit_low : reg_bit_high, (volatile uint32_t)reg);
if(currBit) { // ~400ns HIGH (740ns overall)
NOPx7
NOPx7
}
// ~340ns HIGH
NOPx7
__builtin_arc_nop();

// 820ns LOW; per spec, max allowed low here is 5000ns */
__builtin_arc_sr(reg_bit_low, (volatile uint32_t)reg);
NOPx7
NOPx7

if(bitCounter >= 8) {
bitCounter = 0;
currByte = (uint32_t) (*++p);
}

currBit = 0x80 & currByte;
first = 0;
}
} else if(pindesc->ulGPIOType == SOC_GPIO) {
register uint32_t reg = pindesc->ulGPIOBase + SOC_GPIO_SWPORTA_DR;
register uint32_t reg_val = MMIO_REG_VAL(reg);
uint32_t reg_val = MMIO_REG_VAL(reg);
register uint32_t reg_bit_high = reg_val | (1 << pindesc->ulGPIOId);
register uint32_t reg_bit_low = reg_val & ~(1 << pindesc->ulGPIOId);

while(p < end) {
pix = *p++;
for(mask = 0x80; mask; mask >>= 1) {
MMIO_REG_VAL(reg) = reg_bit_high;
if(pix & mask) {
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
MMIO_REG_VAL(reg) = reg_bit_low;
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
} else {
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
MMIO_REG_VAL(reg) = reg_bit_low;
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
__builtin_arc_nop();
}
loop += 1; // include first, special iteration
while(loop--) {
if(!first) {
currByte <<= 1;
bitCounter++;
}
MMIO_REG_VAL(reg) = first ? reg_bit_low : reg_bit_high;
if(currBit) { // ~430ns HIGH (740ns overall)
NOPx7
NOPx7
__builtin_arc_nop();
}
// ~310ns HIGH
NOPx7

// 850ns LOW; per spec, max allowed low here is 5000ns */
MMIO_REG_VAL(reg) = reg_bit_low;
NOPx7
NOPx7

if(bitCounter >= 8) {
bitCounter = 0;
currByte = (uint32_t) (*++p);
}

currBit = 0x80 & currByte;
first = 0;
}
}

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