Must base pins be factors of 8 when used with setnib?
ke4pjw
Posts: 1,179
Dumb question. It has been months since I have programmed the P2.
Are "base pins" required to be 0,8,16,24,32,40,48,56 ?
I want to do something like this, where tx is actually pin 44.
altsn tx,#outa ' What is the base PIN?
setnib pinnib ' Turn off the pins with 0 code
Comments
That's fine. For SETNIB you are limited to multiples of four. It's not really a base pin but rather a cogRAM index.
In terms of pin ops like PINH() a base pin can be any pin number, afaik.
Man, I lucked out when I placed those lines on pin 44 then
As always, thanks evanh!
Are you writing a group of four bits to a specific base pin? You could borrow from the Spin2 interpreter pinwrite() code. This works for any pin, though all four pins must be in the same 32-bit outputs register.
pri write4(pin, value) | mask org testb pin, #5 wc ' check for outa or outb bitc .write, #9 ' adjust write register mov mask, #%1111 ' make 4-pin mask shl mask, pin ' align to pin shl value, pin or pin, #%11_000000 ' make 4-pin group setq mask .write muxq outa, value dirh pin ' enable pins endHey @JonnyMac ! I just wanted to do minimal code changes to the pixel driver of yours that I modified to do 8 ports at a time, but instead just drive 4. (This is my hacked up 8 port driver, not your good multipin driver) I am current using:
altsb tx,#outa ' What is the base PIN? setbyte pinbyte ' Turn off the pins with 0 codeI have built a "long range" board I that can plug into the quad RS-485 driver I have on my light controller. I designed the transmitter for DMX, but then realized I can also send ws2811 data to it to drive some of the problematic 80ft runs I have.
Interesting. I normally use a TC4427 for pixel driving. I wouldn't have thought the RS-485 driver would tolerate the narrow pulses of the WS2811 signal. Nice to know.
From my research, RS-485 should be able to do 5Mbps at 100ft, which should be more than enough for the type of signaling used by pixels.
I know other pixel controllers have been doing similar for years. They call this type of receiver a "dumb receiver". No MCU or anything, just pixel data.
I will let you know how well it works.
Those coloured lines on the graph don't look right. More jitter should come closer to the conservative line, not further away. Ie: The conservative line is rated for high level of jitter.
@JonnyMac it works! This is though 210ft of cat-5e. The waveform looks square.
FYI: I had to change the way the pin group is calculated which was called out above, but I forgot to change. You need to divide the pin number by 4 instead of 8 (shift right 2 instead of 3). tx is my pin
changed to
That took a while for me to figure out. I had forgotten about having to do that in my code. Pin group 0 always works no matter if it is a nib/byte/etc. because it starts at 0. That's when I realized the problem and re-read what was stated in this post by @JonnyMac . The method I use to set the pin group is different.
@ke4pjw
terry, tried to watch video but get an error.
jim