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