From 683703a4720681107d17f44eae774d8c50797af7 Mon Sep 17 00:00:00 2001
From: Thomas White <taw@physics.org>
Date: Sun, 1 Oct 2023 08:44:30 +0200
Subject: Backup before messing with DMA

---
 pixelhub.cpp | 129 ++++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 92 insertions(+), 37 deletions(-)

diff --git a/pixelhub.cpp b/pixelhub.cpp
index 506e1a1..660ecc7 100644
--- a/pixelhub.cpp
+++ b/pixelhub.cpp
@@ -35,24 +35,66 @@ struct pixel_strip
 	uint offset;
 	uint32_t pixelbuf[256];
 	int rgbw;
+	uint dma_chan;
 };
 
 
-static inline void put_pixel(struct pixel_strip *p, uint32_t pixel_grb) {
+static inline void put_pixel(struct pixel_strip *p, uint32_t pixel_grb)
+{
 	pio_sm_put_blocking(p->pio, p->pio_sm, pixel_grb);
 }
 
 
-static inline uint32_t urgb_u32(uint8_t r, uint8_t g, uint8_t b) {
+static inline uint32_t urgb_u32(uint8_t r, uint8_t g, uint8_t b)
+{
 	return ((uint32_t)(g)<<24) | ((uint32_t)(r)<<16) | ((uint32_t)(b)<<8);
 }
 
 
-static inline uint32_t wrgb_u32(uint8_t r, uint8_t g, uint8_t b, uint8_t w) {
+static inline uint32_t wrgb_u32(uint8_t r, uint8_t g, uint8_t b, uint8_t w)
+{
 	return ((uint32_t)(g)<<24) | ((uint32_t)(r)<<16) | ((uint32_t)(b)<<8) | (uint32_t)(w);
 }
 
 
+uint dma_chan;
+dma_channel_config dma_conf;
+struct pixel_strip strips[8];
+int n_strips;
+int cur_strip = 0;
+
+
+static void set_dma()
+{
+	struct pixel_strip *p = &strips[cur_strip];
+	channel_config_set_dreq(&dma_conf,
+	                        pio_get_dreq(p->pio, p->pio_sm, true));
+	dma_channel_configure(p->dma_chan, &dma_conf,
+	                      &p->pio->txf[p->pio_sm],  /* Dest */
+	                      &p->pixelbuf,             /* Source */
+	                      p->num_pixels,
+	                      true);
+}
+
+
+static int64_t next_strip(alarm_id_t id, void *vp)
+{
+	cur_strip++;
+	if ( cur_strip >= n_strips ) cur_strip = 0;
+	set_dma();
+	return 0;
+}
+
+
+static void dma_complete()
+{
+	if ( dma_hw->ints0 & 1<<dma_chan ) {
+		dma_hw->ints0 = 1<<dma_chan;
+		add_alarm_in_us(400, next_strip, NULL, true);
+	}
+}
+
+
 static void init_pixel_strip(struct pixel_strip *p)
 {
 	int i;
@@ -62,66 +104,79 @@ static void init_pixel_strip(struct pixel_strip *p)
 	ws2812_program_init(p->pio, p->pio_sm, p->offset, p->pin, 800000, p->rgbw);
 
 	for ( i=0; i<p->num_pixels; i++ ) {
-		p->pixelbuf[i] = 0;
+		p->pixelbuf[i] = 127;
 	}
-
 }
 
 
 int main()
 {
 	DmxInput dmx_in;
-	struct pixel_strip p1;
-	struct pixel_strip p2;
 	uint8_t dmxbuf[512];
 	int i;
 	int blink = 1;
 
-	p1.pin = 2;
-	p1.num_pixels = 8;
-	p1.rgbw = false;
-	p1.pio = pio0;
+	strips[0].pin = 2;
+	strips[0].num_pixels = 8;
+	strips[0].rgbw = false;
+	strips[0].pio = pio0;
 
-	p2.pin = 3;
-	p2.num_pixels = 1;
-	p2.rgbw = true;
-	p2.pio = pio0;
+	strips[1].pin = 3;
+	strips[1].num_pixels = 1;
+	strips[1].rgbw = true;
+	strips[1].pio = pio0;
+
+	n_strips = 1;
 
 	/* Initialise DMX */
 	dmx_in.begin(dmx_rx_pin, 1, 512);
 
 	/* Initialise Neopixels */
-	init_pixel_strip(&p1);
-	init_pixel_strip(&p2);
-	int npx = 8;
+	init_pixel_strip(&strips[0]);
+	init_pixel_strip(&strips[1]);
+
+	/* Start DMA */
+	dma_chan = dma_claim_unused_channel(true);
+	dma_conf = dma_channel_get_default_config(dma_chan);
+	channel_config_set_read_increment(&dma_conf, true);
+	channel_config_set_write_increment(&dma_conf, false);
+	//irq_set_exclusive_handler(DMA_IRQ_0, dma_complete);
+	//dma_channel_set_irq0_enabled(dma_chan, true);
+	//irq_set_enabled(DMA_IRQ_0, true);
+	cur_strip = 0;
+	//set_dma();
+
+	struct pixel_strip *p = &strips[0];
+	channel_config_set_dreq(&dma_conf,
+	                        pio_get_dreq(p->pio, p->pio_sm, true));
+	dma_channel_configure(p->dma_chan, &dma_conf,
+	                      &p->pio->txf[p->pio_sm],  /* Dest */
+	                      p->pixelbuf,             /* Source */
+	                      p->num_pixels,
+	                      true);
 
 	/* Status LED */
 	gpio_init(PICO_DEFAULT_LED_PIN);
 	gpio_set_dir(PICO_DEFAULT_LED_PIN, GPIO_OUT);
 
+	int loop = 0;
 	while (1) {
 
-		dmx_in.read(dmxbuf);
-
-		int dmxpos = 1;  /* Numbering starts at 1 */
-		for ( i=0; i<p1.num_pixels; i++) {
-			p1.pixelbuf[i] = urgb_u32(dmxbuf[dmxpos++],
-			                          dmxbuf[dmxpos++],
-			                          dmxbuf[dmxpos++]);
-		}
-		for ( i=0; i<p2.num_pixels; i++) {
-			p2.pixelbuf[i] = wrgb_u32(dmxbuf[dmxpos++],
-			                          dmxbuf[dmxpos++],
-			                          dmxbuf[dmxpos++],
-			                          dmxbuf[dmxpos++]);
-		}
+		//dmx_in.read(dmxbuf);
 
-		for ( i=0; i<npx; i++) {
-			put_pixel(&p1, p1.pixelbuf[i]);
-			put_pixel(&p2, p2.pixelbuf[i]);
-		}
+		//int dmxpos = 1;  /* Numbering starts at 1 */
+		//for ( i=0; i<strips[0].num_pixels; i++) {
+		//	strips[0].pixelbuf[i] = urgb_u32(0, 0, 32);
+		//}
+		//for ( i=0; i<strips[1].num_pixels; i++) {
+		//	strips[1].pixelbuf[i] = wrgb_u32(0, 64, 0, 0);
+		//}
 
 		gpio_put(PICO_DEFAULT_LED_PIN, blink);
-		blink = 1 - blink;
+		loop++;
+		if ( loop > 1000000 ) {
+			loop = 0;
+			blink = 1 - blink;
+		}
 	}
 }
-- 
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