Put NeoPixels on your LAN.
Simple Arduino program to copy bits from UDP packets to an attached string of NeoPixels. The basic concept is to make the Arduino simple as possible and place all the complexity in a program somewhere else on your network.
The UDP payload should be the bytes 0x27 0x1d 0x0a 0x3c followed by 4 bytes of pixel data, RGBW, for every NeoPixel in your string (send 4 bytes / pixel, even if the NeoPixels are only RGB).
If the Arduino receives a packet (including broadcast packets) with the wrong length (something besides 4 + 4 * STRIP_LEN) it will send a description packet back to the sender. The description packet payload will be:
- 4 byte magic : 0x27 0x1d 0x0a 0x3c
- 1 byte 'unit id' : Set by
UNIT_ID - 2 byte (big endian) string length : Set by
STRIP_LEN - 1 byte channel count, 3 or 4 : Inferred from
PIXEL_TYPE
The (single) .ino file assumes the there is a parameters.h file in
the same directory that provides information about your environment
and NeoPixel string.
Example parameters.h file:
#define STRIP_PIN 6
#define STRIP_LEN 32
#define UNIT_ID 03
#define PIXEL_TYPE NEO_GRB + NEO_KHZ800
#define SSID "Enterprise"
#define WIFI_PASSWORD "IAMADOCTORNOTANITGUY"
While we want make the code running on the Arduino 'dumb', having it protect itself against bugs in the remote program that might damage the hardware is a good idea.
Some NeoPixel setups have limits on how much power they can safely can draw. For example a NeoPixel feather wing should only draw 1A sustained, and in practice the power supply of most feathers won't actually support that high a current.
Empirically the current draw of a NeoPixels is linear in the sum of
the 3 (or 4) bytes that it has been set too. Providing a value for
POWER_LIMIT in parameters.h will cause the system to limit the sum
of bytes sent to the NeoPixels to POWER_LIMIT. If the sum of the
byte values in a packet's pixel data is greater than POWER_LIMIT
then each value will be scaled by POWER_LIMIT divided by sum before
sending the bytes to the NeoPixels.