1 files changed, 53 insertions, 0 deletions
diff --git a/ports/esp32/espneopixel.c b/ports/esp32/espneopixel.c
new file mode 100644
index 000000000..829c8b1c8
--- /dev/null
+++ b/ports/esp32/espneopixel.c
@@ -0,0 +1,53 @@
+// 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 "py/mpconfig.h"
+#include "py/mphal.h"
+#include "modesp.h"
+
+void IRAM_ATTR esp_neopixel_write(uint8_t pin, uint8_t *pixels, uint32_t numBytes, uint8_t timing) {
+    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 = ets_get_cpu_frequency() * 1000000;
+
+    if (timing == 1) {
+        // 800 KHz
+        time0 = (fcpu * 0.35) / 1000000; // 0.35us
+        time1 = (fcpu * 0.8) / 1000000; // 0.8us
+        period = (fcpu * 1.25) / 1000000; // 1.25us per bit
+    } else {
+        // 400 KHz
+        time0 = (fcpu * 0.5) / 1000000; // 0.35us
+        time1 = (fcpu * 1.2) / 1000000; // 0.8us
+        period = (fcpu * 2.5) / 1000000; // 1.25us per bit
+    }
+
+    uint32_t irq_state = mp_hal_quiet_timing_enter();
+    for (t = time0;; t = time0) {
+        if (pix & mask) t = time1;                                  // Bit high duration
+        while (((c = mp_hal_ticks_cpu()) - startTime) < period);    // Wait for bit start
+        GPIO_REG_WRITE(GPIO_OUT_W1TS_REG, pinMask);                 // Set high
+        startTime = c;                                              // Save start time
+        while (((c = mp_hal_ticks_cpu()) - startTime) < t);         // Wait high duration
+        GPIO_REG_WRITE(GPIO_OUT_W1TC_REG, pinMask);                 // Set low
+        if (!(mask >>= 1)) {                                        // Next bit/byte
+            if(p >= end) break;
+            pix  = *p++;
+            mask = 0x80;
+        }
+    }
+    while ((mp_hal_ticks_cpu() - startTime) < period); // Wait for last bit
+    mp_hal_quiet_timing_exit(irq_state);
+}