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// Original version from https://github.com/adafruit/Adafruit_NeoPixel
// Modifications by dpgeorge to support auto-CPU-frequency detection
// This is a mash-up of the Due show() code + insights from Michael Miller's
// ESP8266 work for the NeoPixelBus library: github.com/Makuna/NeoPixelBus
// Needs to be a separate .c file to enforce ICACHE_RAM_ATTR execution.
#include "c_types.h"
#include "eagle_soc.h"
#include "user_interface.h"
#include "espneopixel.h"
#define NEO_KHZ400 (1)
static uint32_t _getCycleCount(void) __attribute__((always_inline));
static inline uint32_t _getCycleCount(void) {
uint32_t ccount;
__asm__ __volatile__("rsr %0,ccount":"=a" (ccount));
return ccount;
}
void /*ICACHE_RAM_ATTR*/ esp_neopixel_write(uint8_t pin, uint8_t *pixels, uint32_t numBytes, bool is800KHz) {
uint8_t *p, *end, pix, mask;
uint32_t t, time0, time1, period, c, startTime, pinMask;
pinMask = 1 << pin;
p = pixels;
end = p + numBytes;
pix = *p++;
mask = 0x80;
startTime = 0;
uint32_t fcpu = system_get_cpu_freq() * 1000000;
#ifdef NEO_KHZ400
if(is800KHz) {
#endif
time0 = fcpu / 2500000; // 0.4us
time1 = fcpu / 1250000; // 0.8us
period = fcpu / 800000; // 1.25us per bit
#ifdef NEO_KHZ400
} else { // 400 KHz bitstream
time0 = fcpu / 2000000; // 0.5uS
time1 = fcpu / 833333; // 1.2us
period = fcpu / 400000; // 2.5us per bit
}
#endif
for(t = time0;; t = time0) {
if(pix & mask) t = time1; // Bit high duration
while(((c = _getCycleCount()) - startTime) < period); // Wait for bit start
GPIO_REG_WRITE(GPIO_OUT_W1TS_ADDRESS, pinMask); // Set high
startTime = c; // Save start time
while(((c = _getCycleCount()) - startTime) < t); // Wait high duration
GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, pinMask); // Set low
if(!(mask >>= 1)) { // Next bit/byte
if(p >= end) break;
pix = *p++;
mask = 0x80;
}
}
while((_getCycleCount() - startTime) < period); // Wait for last bit
}
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