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UCS1903

1-wire RGB · Chipone Technology · ucs

Channels
RGB
Bits / channel
8
Supply
5–24 V
PWM
—
Backup data
no
Packages
0

A ChipOne external driver IC, common in older and cheaper 12 V strip. At 400 kHz it is half the speed of the WS2812 family, which limits how many LEDs you can refresh at a usable frame rate.

Timing

UCS1903 bit timingUCS1903 bit timing: a zero bit is 500 nanoseconds high then 2000 low; a one bit is 2000 high then 500 low; reset 0 microseconds low1 · Bit encoding, to scaleDINhighlowbit 0 period 2500 nsbit 1 period 2500 nsT0H 500 nsT1H 2000 nsT0L 2000 nsT1L 500 ns"0" bit"1" bit0500100015002000250030003500400045005000time, ns2 · One frame: 24 bits, most-significant bit firstDIN170110010007100110101700101100bitch 1 · 8 bitsch 2 · 8 bitsch 3 · 8 bitsChannel order not recorded for this protocol · frame = 24 × ~2500 ns ≈ 60 µs · example data, first bits 1 0 1 …3 · RESET / latchlast bits of frame 1first bits of frame 2LEDs latch the data they receivedRESET: DIN low ≥ 0 µs (not to scale)4 · Cascade: each DOUT feeds the next DINMCULED 1DINDOUTLED 2DINDOUTLED NDINDOUTLED 1 keeps the first 24 bits, re-shapes the signal and sends the rest out on DOUT;LED 2 keeps the next 24, and so on. The last LED's DOUT is left unconnected.
T0H 500 / T0L 2000 · T1H 2000 / T1L 500 ns · period 2500 ns · reset 0 µs source: fastled (driver-tuned, not the datasheet)
SourceT0HT0LT1HT1LPeriodRateReset±
fastled ↗ 500 ns 2000 ns 2000 ns 500 ns 2500 ns 400 kHz 0 µs —
FastLED also carries UCS1903B at 800 kHz (400/450/450). The plain UCS1903 is the 400 kHz part - half the data rate of a WS2812B, which matters on long runs.

Clones & compatibility

“Compatible” is never stated bare here — each relationship carries how strong the claim is, and what bites if you assume too much.

  • electrically similar WS2811

    Both are external three-channel drivers used in 12 V strip at a similar data rate, but the bit timings differ and they are not interchangeable without reconfiguring the driver. source ↗

Library support

FastLED
UCS1903 ↗
WLED
UCS1903

Parts using this protocol

No package is catalogued for this protocol yet — it is seeded for family completeness, or it is a driver IC that drives external LEDs rather than shipping as an integrated package.

Dating evidence

Evidence, not a release date. A library commit proves the part existed by that date and says nothing about how long before.

  • 2012-06-09 first library support FastLED — first commit introducing UCS1903 ↗ day