Pen Up / Pen Down

[Windell Oskay]

I’m not sure what “outboard” means in this case.

I’m looking at the schematic diagram now, and I don’t see anything that is inconsistent with the actual circuit board. If you think that there is, please specify exactly what diagram you are looking at, what it is that you are seeing, and how that is inconsistent with the hardware.

I don’t think that the ground pins are labeled with  “+” sign– where are you seeing this? Is this on the schematic or the circuit board?

As it shows on the schematic, each of the relevant I/O connectors (with signals B1, B0, B2, B3) is arranged as three pins. Ground (labeled “GND”, not “+”), 5 V (the middle pin), and the signal line.  If you look at your AxiDraw, the 3-pin connector that is there has three wires that are black (GND), red (middle, +5 V), and white (signal). The other 3-pin connectors are wired up exactly the same way: Ground towards the edge of the board, 5 V power in the middle, and signal furthest from the edge of the board. If you look closely at the circuit board itself, you may (depending on exactly how the screw heads and connectors line up) also be able to see some very small labels there, labeling the vertical row on the edge as “GND”, the middle row as 5V, and the inner pins as B1, B0, B2, B3.

As far as how to hook up your relay, you should follow the manufacturer’s recommendation. There is probably a reason that they specify one terminal as positive.

[vincentP]

In looking at at http://www.schmalzhaus.com/EBB/EBB/EBB_v23/EBB_v23_brd.pdf the pins for rows B0 through B7 appeared to me to be  unnumbered (see below). Each of those pins labeled as ground have a “+” sign inside the circle, so I figured that I should check to make sure I was looking at /looking for the right thing. 

So, not having pin numbers to go by there, I used “outboard” to mean the ground and signal pins, and not the (“inboard”) 5v pin. Sorry I didn’t come up with a better description.

What was not clear to me was that B0 through B7 number individual pins, and not the row of three pins as a unit.

My confusion on the schematic was that the pins are numbered RB0 through RB7 rather than B0 through B7. I should have picked up on that.

Anyway, I think your last response takes care of my hardware questions.

I’ll try to get the Python changes made over the weekend and test it out.

Thanks for your help.

[Windell Oskay]

Ah– I see. You were looking at the board layout picture, rather than a schematic. The crosshairs there (“+”) is where the center of the hole is drilled. I do see how that could be confusing.  

[vincentP]

I probably would have recognized it as that, if it weren’t a pin rather than a hole, but note that not all of the holes have crosshairs in that drawing (note the 5v holes), so it seemed safer to ask.

[vincentP]

OK, Axidraw now paints:

https://www.instagram.com/p/BQanC2albTB/?taken-by=vincentpidone

Thanks for the help, Windell.

[Windell Oskay]

Cool– glad to hear that you’ve got it working. Neat application, too.

[vincentP]

I’ve started a hackaday project to document this:

https://hackaday.io/project/19861-axidraw-becomes-axipaint

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