Improve WS2812 waveform timing

WS2812Serial.cpp

@@ -14,7 +14,7 @@ bool WS2812Serial::begin()
 	  case 26:
 	#endif
 		uart = &KINETISK_UART0;
-		divisor = BAUD2DIV(2400000);
+		divisor = BAUD2DIV(4000000);
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(3);
 		hwtrigger = DMAMUX_SOURCE_UART0_TX;
 		SIM_SCGC4 |= SIM_SCGC4_UART0;
@@ -27,7 +27,7 @@ bool WS2812Serial::begin()
 	  case 58:
 	#endif
 		uart = &KINETISK_UART1;
-		divisor = BAUD2DIV2(2400000);
+		divisor = BAUD2DIV2(4000000);
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(3);
 		hwtrigger = DMAMUX_SOURCE_UART1_TX;
 		SIM_SCGC4 |= SIM_SCGC4_UART1;
@@ -36,7 +36,7 @@ bool WS2812Serial::begin()
 	  case 8: // Serial3
 	  case 20:
 		uart = &KINETISK_UART2;
-		divisor = BAUD2DIV3(2400000);
+		divisor = BAUD2DIV3(4000000);
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(3);
 		hwtrigger = DMAMUX_SOURCE_UART2_TX;
 		SIM_SCGC4 |= SIM_SCGC4_UART2;
@@ -46,7 +46,7 @@ bool WS2812Serial::begin()
 	  case 32: // Serial4
 	  case 62:
 		uart = &KINETISK_UART3;
-		divisor = BAUD2DIV3(2400000);
+		divisor = BAUD2DIV3(4000000);
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(3);
 		hwtrigger = DMAMUX_SOURCE_UART3_TX;
 		SIM_SCGC4 |= SIM_SCGC4_UART3;
@@ -54,7 +54,7 @@ bool WS2812Serial::begin()
 
 	  case 33: // Serial5
 		uart = &KINETISK_UART4;
-		divisor = BAUD2DIV3(2400000);
+		divisor = BAUD2DIV3(4000000);
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(3);
 		hwtrigger = DMAMUX_SOURCE_UART4_RXTX;
 		SIM_SCGC1 |= SIM_SCGC1_UART4;
@@ -63,7 +63,7 @@ bool WS2812Serial::begin()
 	#if defined(__MK64FX512__)
 	  case 48: // Serial6
 		uart = &KINETISK_UART5;
-		divisor = BAUD2DIV3(2400000);
+		divisor = BAUD2DIV3(4000000);
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(3);
 		hwtrigger = DMAMUX_SOURCE_UART5_RXTX;
 		SIM_SCGC1 |= SIM_SCGC1_UART5;
@@ -74,21 +74,21 @@ bool WS2812Serial::begin()
 	  case 1: // Serial1
 	  case 5:
 		uart = &KINETISK_UART0;
-		divisor = 2;
+		divisor = 1;
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(3);
 		hwtrigger = DMAMUX_SOURCE_UART0_TX;
 		SIM_SCGC4 |= SIM_SCGC4_UART0;
 		break;
 	  case 4:
 		uart = &KINETISK_UART0;
-		divisor = 2;
+		divisor = 1;
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(2);
 		hwtrigger = DMAMUX_SOURCE_UART0_TX;
 		SIM_SCGC4 |= SIM_SCGC4_UART0;
 		break;
 	  case 24:
 		uart = &KINETISK_UART0;
-		divisor = 2;
+		divisor = 1;
 		portconfig = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(4);
 		hwtrigger = DMAMUX_SOURCE_UART0_TX;
 		SIM_SCGC4 |= SIM_SCGC4_UART0;
@@ -108,7 +108,7 @@ bool WS2812Serial::begin()
 #elif defined(KINETISL)
 	uart->BDH = (divisor >> 8) & 0x1F;
 	uart->BDL = divisor & 0xFF;
-	uart->C4 = 9;
+	uart->C4 = 11;
 #endif
 	uart->C1 = 0;
 	uart->C2 = UART_C2_TE | UART_C2_TIE;
@@ -136,16 +136,7 @@ void WS2812Serial::show()
 		yield();
 	}
 #endif
-	// wait 300us WS2812 reset time
-	uint32_t min_elapsed = ((numled * 34134) >> 10) + 300;
-	if (min_elapsed < 2500) min_elapsed = 2500;
-	uint32_t m;
-	while (1) {
-		m = micros();
-		if ((m - prior_micros) > min_elapsed) break;
-		yield();
-	}
-	prior_micros = m;
+	// copy drawing buffer to frame buffer
 	const uint8_t *p = drawBuffer;
 	const uint8_t *end = p + (numled * 3);
 	uint8_t *fb = frameBuffer;
@@ -162,26 +153,36 @@ void WS2812Serial::show()
 		  case WS2812_BRG: n = (b << 16) | (r << 8) | g; break;
 		  case WS2812_BGR: n = (b << 16) | (g << 8) | r; break;
 		}
-		const uint8_t *stop = fb + 8;
+		const uint8_t *stop = fb + 12;
 		do {
-			uint8_t x = 0x92;
-			if (!(n & 0x00800000)) x |= 0x01;
-			if (!(n & 0x00400000)) x |= 0x04;
-			if (!(n & 0x00200000)) x |= 0x20;
-			n <<= 3;
+			uint8_t x = 0x08;
+			if (!(n & 0x00800000)) x |= 0x07;
+			if (!(n & 0x00400000)) x |= 0xE0;
+			n <<= 2;
 			*fb++ = x;
 		} while (fb < stop);
 	}
+	// wait 300us WS2812 reset time
+	uint32_t min_elapsed = (numled * 30) + 300;
+	if (min_elapsed < 2500) min_elapsed = 2500;
+	uint32_t m;
+	while (1) {
+		m = micros();
+		if ((m - prior_micros) > min_elapsed) break;
+		yield();
+	}
+	prior_micros = m;
+	// start DMA transfer to update LEDs  :-)
 #if defined(KINETISK)
-	dma->sourceBuffer(frameBuffer, numled * 8);
+	dma->sourceBuffer(frameBuffer, numled * 12);
 	dma->transferSize(1);
-	dma->transferCount(numled * 8);
+	dma->transferCount(numled * 12);
 	dma->disableOnCompletion();
 	dma->enable();
 #elif defined(KINETISL)
 	dma->CFG->SAR = frameBuffer;
 	dma->CFG->DSR_BCR = 0x01000000;
-	dma->CFG->DSR_BCR = numled * 8;
+	dma->CFG->DSR_BCR = numled * 12;
 	dma->CFG->DCR = DMA_DCR_ERQ | DMA_DCR_CS | DMA_DCR_SSIZE(1) |
 		DMA_DCR_SINC | DMA_DCR_DSIZE(1) | DMA_DCR_D_REQ;
 #endif

examples/BasicTest/BasicTest.ino

@@ -10,7 +10,7 @@ const int pin = 1;
 //   Teensy 3.6:  1, 5, 8, 10, 20, 26, 32, 33
 
 byte drawingMemory[numled*3];
-DMAMEM byte displayMemory[numled*8];
+DMAMEM byte displayMemory[numled*12];
 
 WS2812Serial leds(numled, displayMemory, drawingMemory, pin, WS2812_GRB);