Software functions for MSP430 to drive WS2812/B RGB LEDs via one-wire bus
The SPI peripheral will be used in cooperation with one of two transport stream encodings schemes. One 3-bit and one 4-bit encoding was implemented for a SPI clock speed as low as 2.66MHz.
/*
- 3-bit encoding *
- 8 bits from LED color stream encoded in 3 byte for transport stream (SPI TX)
- or: 1 bit from LED color stream encoded in 3 bit for transport stream
-
_ - ZERO: 100 |__
-
__ - ONE : 110 |_
- the bti in the middle defines the value
- data stream: 0x23 0 0 1 0 0 0 1 1
- encoding: 1x01x01x01x01x01x01x01x0
- transport stream: 100100110100100100110110
- initial mask: 0x92 0x49 0x24 100100100100100100100100
- sourcebit : 7 6 5 4 3 2 1 0
- encoding : 1x01x01x01x01x01x01x01x0
- targetbit : 6 3 0 5 2 7 4 1
- targetbyte: | 0 | 1 | 2 |
- sourcebit -> (targetbit,targetbyte)
- 7->(6,0)
- 6->(3,0)
- 5->(0,0)
- 4->(5,1)
- 3->(2,1)
- 2->(7,2)
- 1->(4,2)
- 0->(1,2) */
/*
- 4-bit encoding *
- 2 bits from LED color stream encoded in 1 byte for transport stream (SPI TX)
- or: 1 bit from LED color stream encoded in 4 bit for transport stream
-
_ - ZERO: 1000 = 0x8 |___
-
___ - ONE : 1110 = 0xE |_
- SPI Clock around 3.2MHz (e.g. 6.7MHz/2 = 3.35MHz)
*/ #define ZEROPATTERN 0x8 // 4-bit #define ONEPATTERN 0xE // 4-bit // _ _ #define ZEROZEROPATTERN ((ZEROPATTERN<<4) | ZEROPATTERN) // 10001000 || | // _ ___ #define ZEROONEPATTERN ((ZEROPATTERN<<4) | ONEPATTERN) // 10001110 || | // ___ _ #define ONEZEROPATTERN (( ONEPATTERN<<4) | ZEROPATTERN) // 11101000 || |__ // ___ ___ #define ONEONEPATTERN (( ONEPATTERN<<4) | ONEPATTERN) // 11101110 || |