This should make using the WS2812 examples a bit easier. (#84)

* This should make using the WS2812 examples a bit easier.
Moved parameters to the top as defines:
- Number of LEDs in your NeoPixel/WS2812 strip/ring
- Flag if the LEDs are WRGB or not
Changed PIN to 2 as pin 0 is used for serial UART.

pio/ws2812/ws2812.c

@@ -12,6 +12,13 @@
 #include "hardware/clocks.h"
 #include "ws2812.pio.h"
 
+#define IS_RGBW true
+#define NUM_PIXELS 150
+#ifndef PICO_DEFAULT_WS2812_PIN
+#warning "no WS2812 default PIN defined for board, please check if pin 2 is okay"
+#define PICO_DEFAULT_WS2812_PIN 2
+#endif
+
 static inline void put_pixel(uint32_t pixel_grb) {
  pio_sm_put_blocking(pio0, 0, pixel_grb << 8u);
 }
@@ -71,8 +78,6 @@ const struct {
  {pattern_greys, "Greys"},
 };
 
-const int PIN_TX = 0;
-
 int main() {
  //set_sys_clock_48();
  stdio_init_all();
@@ -83,7 +88,7 @@ int main() {
  int sm = 0;
  uint offset = pio_add_program(pio, &ws2812_program);
 
- ws2812_program_init(pio, sm, offset, PIN_TX, 800000, true);
+ ws2812_program_init(pio, sm, offset, PICO_DEFAULT_WS2812_PIN, 800000, IS_RGBW);
 
  int t = 0;
  while (1) {
@@ -92,9 +97,9 @@ int main() {
  puts(pattern_table[pat].name);
  puts(dir == 1 ? "(forward)" : "(backward)");
  for (int i = 0; i < 1000; ++i) {
- pattern_table[pat].pat(150, t);
+ pattern_table[pat].pat(NUM_PIXELS, t);
  sleep_ms(10);
  t += dir;
  }
  }
-}
+}

pio/ws2812/ws2812_parallel.c

@@ -16,7 +16,8 @@
 #include "ws2812.pio.h"
 
 #define FRAC_BITS 4
-#define PIN_TX 0
+#define NUM_PIXELS 64
+#define WS2812_PIN_BASE 2
 
 // horrible temporary hack to avoid changing pattern code
 static uint8_t *current_string_out;
@@ -174,17 +175,15 @@ void dither_values(const value_bits_t *colors, value_bits_t *state, const value_
  }
 }
 
-#define MAX_LENGTH 100
-
-// requested colors * 4 to allow for WRGB
-static value_bits_t colors[MAX_LENGTH * 4];
+// requested colors * 4 to allow for RGBW
+static value_bits_t colors[NUM_PIXELS * 4];
 // double buffer the state of the string, since we update next version in parallel with DMAing out old version
-static value_bits_t states[2][MAX_LENGTH * 4];
+static value_bits_t states[2][NUM_PIXELS * 4];
 
 // example - string 0 is RGB only
-static uint8_t string0_data[MAX_LENGTH * 3];
-// example - string 1 is WRGB
-static uint8_t string1_data[MAX_LENGTH * 4];
+static uint8_t string0_data[NUM_PIXELS * 3];
+// example - string 1 is RGBW
+static uint8_t string1_data[NUM_PIXELS * 4];
 
 string_t string0 = {
  .data = string0_data,
@@ -213,7 +212,7 @@ string_t *strings[] = {
 #define DMA_CHANNELS_MASK (DMA_CHANNEL_MASK | DMA_CB_CHANNEL_MASK)
 
 // start of each value fragment (+1 for NULL terminator)
-static uintptr_t fragment_start[MAX_LENGTH * 4 + 1];
+static uintptr_t fragment_start[NUM_PIXELS * 4 + 1];
 
 // posted when it is safe to output a new set of values
 static struct semaphore reset_delay_complete_sem;
@@ -286,7 +285,7 @@ int main() {
  int sm = 0;
  uint offset = pio_add_program(pio, &ws2812_parallel_program);
 
- ws2812_parallel_program_init(pio, sm, offset, PIN_TX, count_of(strings), 800000);
+ ws2812_parallel_program_init(pio, sm, offset, WS2812_PIN_BASE, count_of(strings), 800000);
 
  sem_init(&reset_delay_complete_sem, 1, 1); // initially posted so we don't block first time
  dma_init(pio, sm);
@@ -300,19 +299,17 @@ int main() {
  int brightness = 0;
  uint current = 0;
  for (int i = 0; i < 1000; ++i) {
- int n = 64;
-
  current_string_out = string0.data;
  current_string_4color = false;
- pattern_table[pat].pat(n, t);
+ pattern_table[pat].pat(NUM_PIXELS, t);
  current_string_out = string1.data;
  current_string_4color = true;
- pattern_table[pat].pat(n, t);
+ pattern_table[pat].pat(NUM_PIXELS, t);
 
- transform_strings(strings, count_of(strings), colors, n * 4, brightness);
- dither_values(colors, states[current], states[current ^ 1], n * 4);
+ transform_strings(strings, count_of(strings), colors, NUM_PIXELS * 4, brightness);
+ dither_values(colors, states[current], states[current ^ 1], NUM_PIXELS * 4);
  sem_acquire_blocking(&reset_delay_complete_sem);
- output_strings_dma(states[current], n * 4);
+ output_strings_dma(states[current], NUM_PIXELS * 4);
 
  current ^= 1;
  t += dir;