WS2812 smartpin driver

Hi All

Here's a demo of a WS2812 driver using smartpins.

A table is generated in LUT of 24 bit patterns representing color byte waveforms.
A smartpin is configured in sync tx mode and fed with the LUT patterns.
The same sync tx smartpin gets its clock source from a neighbour smartpin configured in transition mode.

More "lanes" can easily be added(5 more of the same clock) by adding more sync tx smartpins.
Prop2 WS2812 demo using smartpins
Version 0.2
ozpropdev Feb 15th 2019

		sys_clk = 25_000_000
		us = sys_clk / 1_000_000
		ws2812_load = 51 * us
		_200ns = us * 200 / 1000

		num_leds = 64

		clk = 14
		ws2812 = 15

dat		org

		hubset	#0

		wrpin	#%1_00101_0,#clk	'transition mode
		wxpin	##_200ns,#clk
		dirh	#clk

		wrpin	##%1111 << 24 | %1_11100_0,#ws2812	'sync tx mode
		wxpin	#%1_00000 | 23,#ws2812
		dirh	#ws2812

'build ws812 waveform data into lut for each byte

'e.g. byte $8c becomes %001_001_011_011_001_001_001_011

		mov	index,#0
build		mov	count,#8		'number of bits
		mov	pa,index
		mov	pb,#0
.loop		testb	pa,#7 wc
		shl	pb,#3
		or	pb,#1			'0 = %100  (1/3 t)
	if_c	or	pb,#%10			'1 = %110  (2/3 t)
		shl	pa,#1
		djnz	count,#.loop
		shl	pb,#32-24
		rev	pb			'prepare for msb shifted first
		wrlut	pb,index
		incmod	index,#255 wz
	if_nz	jmp	#build

		getct	time
		addct1	time,delay

'Main loop

'send data to ws2812 devices

update_ws2812	loc	ptra,#@led_buffer	'iitialize pointer
		mov	leds,#num_leds
next_led	rdlong	rgb,ptra++		'get grb data
		mov	count,#3		'3 * 8 bits 
next_color	getbyte	pb,rgb,#2		'get color byte
		shl	rgb,#8
		rdlut	pa,pb			'convert to waveform
		wypin	pa,#ws2812		'load sync tx with 24 bit waveform
		wypin	#48,#clk		'start 48 clock transitions
busy		testp	#clk wc			'wait for smartpin completion
	if_nc	jmp	#busy
		rdpin	0,#clk			'clear smartpin
		djnz	count,#next_color
		djnz	leds,#next_led
		waitx	##ws2812_load		'data low for >50Us

'shift led pattern in led buffer

		pollct1	wc
	if_nc	jmp	#update_ws2812

		addct1	time,delay
		loc	ptra,#@led_buffer
		loc	ptrb,#@led_buffer+4
		rdlong	pb,ptra
		rep	#2,#63
		rdlong	pa,ptrb++
		wrlong	pa,ptra++
		wrlong	pb,ptra
		jmp	#update_ws2812

time		long	0
delay		long	sys_clk  / 20

count		long	0
index		long	0
rgb		long	0
leds		long	0
lut		long	0

		orgh	$400

		long	$00_1f_00_00[4]	'green
		long	$00_00_1f_00[4]	'red
		long	$00_00_00_1f[4]	'blue
		long	$00_00_1f_1f[4]	'magenta
		long	$00_1f_00_1f[4]	'cyan
		long	$00_1f_1f_00[4]	'yellow
		long	$00_1f_1f_1f[4]	'yehite
		long	0[4]
		long	$00_1f_00_00[8]	'green
		long	$00_00_1f_00[8]	'red
		long	$00_00_00_1f[8]	'blue
		long	$00_00_1f_1f[8]	'magenta

Melbourne, Australia


  • those smartpins are simply a bummer. They save so much code its fantastic.


    I am just another Code Monkey.
    A determined coder can write COBOL programs in any language. -- Author unknown.
    Press any key to continue, any other key to quit

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this post are to be interpreted as described in RFC 2119.
  • Here's an expanded version running 6 lanes(channels).
    Smartpins make this so easy. A single cog can control a huge amount of leds.

    BTW this is running in RCFAST mode with no problems.
    Melbourne, Australia
Sign In or Register to comment.