WS2801 on Raspberry Pi not working

General
1

I can't imagine there might be many people using these (string of 50 water proof RGB LEDS that use 2-wire SPI for data/clock)

I used to have them working in Node-RED last christmas but they only work this year if I say there is only 1 in the string - I can control that one fine

Once I say I have more (say 10) I just get a couple of them lighting up with random colour)

To prove they weren't broken, I installed an old Adafruit python lib and they worked fine

The only hint I'm getting is this error message in the terminal
image

2

Voltage Simon? If I seem to remember they need vdd * 0.7 on the 2 wire SPI, sometimes they work and sometimes not.

[edit] have you got a level shifter handy?

3

:slight_smile:

I've been investigating and it seems that github was updated 18 days ago but npm hasn't caught up

So I installed it direct from github - but now I get a really big error message :frowning:

image
image984Ă—270 173 KB

But, I've tested the underlying npm rpi-gpio library and I can run a native JS file just using node itself so there is hope

4

I missed that you had tried with Python!!

5

I do that myself all the time - it must be age :slight_smile:

1 Like
6

Ha, I blame fingers being faster than the brain. A stupid hypothesis as the fingers are controlled by the brain :slight_smile:

7

Looking at github for the contrib node and then looking at recent changes in the code for its upstream npm package, I can see where the connect function has changed from needing 3 to now needing 4 parameters
Further investigation has found out that the upstream rpi-gpio package has change the package it uses to access the SPI bus and that is the thing causing the issue

Going to see if I can bodge my local copy to get it working!

8

Bodge success :slight_smile:

node.leds.connect(node.numLeds, 0,0 , node.gamma); // bodge to cope with changes in rpi-ws2801 (which changed to using a different underlying spi lib)

2019-12-12 18.42.02
2019-12-12 18.42.023264Ă—1836 1.79 MB

I've raised an issue with the node on github so hopefully it'll get sorted officially

2 Likes
9

Ha, ha - I can see the problem - the red wire (second from the left) is not making a very good contact.

Oops - the other problem might be 'Bott-RED' is empty at this end.

4 Likes
10

Dave, are you using node-red-contrib-merlot?

4 Likes
11

Yes I am - I found it on the drop-down menu in the Human-In category.

3 Likes
12

Anybody found the new node-red-contrib-auto-tidy-up yet?
I also really need it urgently
:wink:

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13

I've been working on it for years but the more I get it to clean up, the messier things end up. Go figure.

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14

If you are using native tidy together with native auto library then it fails most of time cos auto library contains let-it-be library and this overrides most of your custom methods. Took me years of trial and error to figure it out.

5 Likes
15

Wow! And I thought my workbench was messy... :rofl:

16

I vote we move this to the Lounge so as not to scare newcomers!

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That's my desk overflow area for when I can't get anything more on the desk itself :slight_smile:

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18

Posting photos of your desk might be too traumatic for your average viewer!

19

Back to business ...... :slight_smile:

@nlecaude has asked me to do a PR as he is away at moment so I've done that but he'll need to update the main npm package

If anyone actually needs it ASAP- you can just install from my github fork in the meantime

npm install https://github.com/cymplecy/node-red-contrib-rpi-ws2801#Change-to-deal-with-upstream-move-to-use-bus-and-device-instead-of-port

Maybe I could have used a less verbose branch name :slight_smile:

1 Like