Example code does not work: max7219.lua:70: bad argument #1 to 'ipairs' (table or rotable expected, got nil)

[marcelstoer]

Example code does not work: max7219.lua:70: bad argument #1 to 'ipairs' (table or rotable expected, got nil)

[marcelstoer]

Which example? The one from https://github.com/marcelstoer/nodemcu-max7219/blob/master/README.md?
How does summy2.lua:3 look?

[tricoos]

The official example code - summy2.lua (which should be called dummy2.lua btw) just contains the first lines of the example:

max7219 = require("max7219")
max7219.setup({debug = true, numberOfModules = 4, slaveSelectPin = 8})
max7219.write({
    { 0x20, 0x74, 0x54, 0x54, 0x3C, 0x78, 0x40, 0x00 },
    { 0x41, 0x7F, 0x3F, 0x48, 0x48, 0x78, 0x30, 0x00 },
    { 0x38, 0x7C, 0x44, 0x44, 0x6C, 0x28, 0x00, 0x00 },
    { 0x30, 0x78, 0x48, 0x49, 0x3F, 0x7F, 0x40, 0x00 }
  }, { rotate = "left" })

This in conjunction with the latest max7219.lua from the repo leads to this error.

[marcelstoer]

I know that it worked when I last tested. Might be that the changes I pulled in from someone else's fork (45e4460) broke something.

[tricoos]

I could fix it by changing the code to

local c = {}
  for i,char in pairs(chars) do 
  --for i = 1, #chars do
  --  local char = chars[i]
    if transformation.rotate ~= nil then
--      char = rotate(char, transformation.rotate == "left")
    end

However, I still couldn't get it to work with CS connected to D8 (the default in the example) - both displays (I have connected two right now) had all LEDs turned on and nothing could change that. It also locked up the USB connection to the PC (ESPlorer). After connecting CS to D2 and changing it in the code (slaveSelectPin = 2) it works now perfectly.

[marcelstoer]

I can't reproduce any of this, works just fine over here.

Furthermore, I find you initial stacktrace a bit odd:

max7219.lua:70: in function '?'
max7219.lua:177: in function 'write'

Line 70 accesses the char passed to rotate() as a parameter. It seems to be nil so it was missing upon invocation.
Your stack trace says rotate() was called from line 177 but that can't be. The actual invocation is further down on line 180. Be that as it may it looks as if max7219. write () wasn't passed any characters.