About a month ago I bought some NeoPixel clone and decided to create a garland/soundlights for Christmas.
TLDR:
The first problem was to analysing of audio stream in real time, so I found a nice console audio visualizer – cava. And changed it a bit, now instead of showing nice looking bars through ncurses it just prints height of bars. It was done with a little patch:
diff --git a/cava.c b/cava.c
index 48482d6..13e7ce1 100644
--- a/cava.c
+++ b/cava.c
@@ -792,13 +792,6 @@ as of 0.4.0 all options are specified in config file, see in '/home/username/.co
f[i] = 0;
}
- #ifdef NCURSES
- //output: start ncurses mode
- if (om == 1 || om == 2) {
- init_terminal_ncurses(color, bcolor, col, bgcol);
- get_terminal_dim_ncurses(&w, &h);
- }
- #endif
if (om == 3) get_terminal_dim_noncurses(&w, &h);
diff --git a/output/raw.c b/output/raw.c
index b3b9d1e..16196b9 100644
--- a/output/raw.c
+++ b/output/raw.c
@@ -5,6 +5,13 @@
int print_raw_out(int bars, int fp, int is_bin, int bit_format, int ascii_range, char bar_delim, char frame_delim, int f[200]) {
int i;
+ for (i = 0; i < bars; i++) {
+ uint8_t f8 = ((float)f[i] / 10000) * 255;
+ printf("%d ", f8);
+ }
+ printf("\n");
+ return 0;
+
if (is_bin == 1){//binary
if (bit_format == 16 ){//16bit:
Created special config where bars equals to count of leds on the strip:
[general]
bars = 60
[output]
bit_format = 8bit
method = raw
style = mono
And it works:
➜ cava git:(master) ✗ ./cava -p soundlights/cava_config
15 22 34 22 15 11 16 11 8 7 11 8 12 8 8 5 4 6 4 5 4 5 4 4 6 10 8 12 8 12 15 14 9 11 9 14 21 14 20 30 20 16 19 17 13 14 10 9 8 9 8 5 5 7 7 11 10 11 8 7
25 38 58 38 25 18 28 20 14 17 26 18 21 14 16 13 9 10 8 11 7 9 11 9 14 21 21 20 15 23 26 24 17 23 17 24 37 24 35 52 35 28 32 30 22 24 18 16 14 16 16 11 10 15 12 18 18 19 14 14
33 50 75 50 34 24 36 27 19 24 36 24 27 20 27 19 13 13 12 15 15 13 15 12 19 28 31 26 20 31 33 31 23 32 22 31 47 31 45 67 45 36 42 38 28 31 23 21 19 21 21 16 14 20 16 24 23 25 19 18
39 58 87 58 47 32 41 32 22 29 44 29 31 24 34 24 19 15 15 18 20 15 18 15 22 34 38 30 24 37 39 36 28 38 26 36 55 36 52 78 52 42 48 44 33 36 26 24 22 24 25 19 17 23 19 28 27 29 22 21
Next problem was converting of bars heights to colors, I made it simple as possible. Max bar height is 256, so I generated 256 colors with code found on Quora:
def _get_spaced_colors(n):
max_value = 16581375
interval = int(max_value / n)
colors = [hex(i)[2:].zfill(6) for i in range(0, max_value, interval)]
return [(int(i[:2], 16), int(i[2:4], 16), int(i[4:], 16)) for i in colors]
After that I was need to changing led colors from Raspberry Pi, first of all I connected the strip to the board. In documentation they say that the strip should be connected with some level converter and should use external power, but mine works just fine connected straight to Raspberry Pi:
- ground → ground PIN;
- power → 3.3V PIN;
- logic → GPIO PIN 18.
As a software part I used Python library rpi_ws281x and created little app, that reads from stdin and changes leds colors:
import sys
from neopixel import Adafruit_NeoPixel, Color
# LED strip configuration:
LED_COUNT = 60 # Number of LED pixels.
LED_PIN = 18 # GPIO pin connected to the pixels (must support PWM!).
LED_FREQ_HZ = 800000 # LED signal frequency in hertz (usually 800khz)
LED_DMA = 5 # DMA channel to use for generating signal (try 5)
LED_BRIGHTNESS = 255 # Set to 0 for darkest and 255 for brightest
LED_INVERT = False # True to invert the signal (when using NPN transistor level shift)
# Colors:
COLORS_COUNT = 256
COLORS_OFFSET = 50
def _get_strip():
strip = Adafruit_NeoPixel(
LED_COUNT, LED_PIN, LED_FREQ_HZ, LED_DMA, LED_INVERT, LED_BRIGHTNESS)
strip.begin()
for i in range(strip.numPixels()):
strip.setPixelColor(i, Color(0, 0, 0))
strip.setBrightness(100)
return strip
def _get_spaced_colors(n):
max_value = 16581375
interval = int(max_value / n)
colors = [hex(i)[2:].zfill(6) for i in range(0, max_value, interval)]
return [(int(i[:2], 16), int(i[2:4], 16), int(i[4:], 16)) for i in colors]
def _handle_stdin(colors, strip):
while True:
try:
nums = map(int, sys.stdin.readline()[:-1].split())
for i, num in enumerate(nums):
strip.setPixelColor(i, Color(*colors[num]))
strip.show()
except Exception as e:
print e
if __name__ == '__main__':
_handle_stdin(_get_spaced_colors(COLORS_COUNT),
_get_strip())
For sending data to Raspberry Pi I just used ssh, like:
./cava -p soundlights/cava_config | ssh pi@retropie.local sudo python soundlights.py
But there was a problem with buffering, but unbuffer from expect solved it:
unbuffer ./cava -p soundlights/cava_config | ssh pi@retropie.local sudo python soundlights.py
And that’s all.