Specifically, Knitting utility bracers.
And yes, I’ve ran into a snag. I’ll ask the questions down at the end of the post, to let people whose eyes glaze over have a chance to leave first.
Basic Description:
Project is inspired by and roughly modeled after the Knitting Bracers live stream back in October: I’m a little wary of posting a direct link to the video, because this is my first real interactions on the site and I don’t want to trigger spam filters…
However, instead of using the whole Sparkfun MicroView, I’m using the Sparkfun Micro OLED Breakout, plus a LilyPad USB. Also, using a larger battery and larger buttons that will poke through the leather, rather than be underneath the leather.
The buttons are there to increment or decrement digits on the display. Long-holding the decrement button would reset the count to zero. Long-holding the increment button would restore a previously cleared count, in case the long-hold of the decrement button was an accident.
This is also my first project doing something more than following a guide on tinkering with Arduino Unos. My background is in software development, and yes, I am fully aware that the only thing more dangerous than a hardware guy with a software patch is a software guy with a soldering iron.
Initial Assumptions:
I chose the LilyPad USB + Sparkfun Micro OLED Breakout because I wanted the display to be as close to the leather as possible, and I wanted on-board USB based charging of the LiPo battery.
I noticed during research that the display can handle multiple character display modes, from 5 characters on 1 row, 6 characters on 3 rows, to 10 characters on 6 rows. I considered adding a low profile rotary encoder to allow selecting groups of digits in the 3x6 mode, to allow multiple counts to be tracked. (I’m kinda glad I decided to keep it simple, at this point.)
The Build, part 1:
The foam and leather are easy to work with. I’ve got a nice bracer waiting for me to add straps to hold down things like scissors, knitting needles, and loop counters, and for me to put the electronics inside.
I stopped here with the bracer because, before I place the scissors and such, I wanted to know where the electronics parts would go… So, I review the directions, draw a quick picture of which wires go where (no, not an actual schematic… Like I said, I’m a software guy), and get the wires hooked up.
Then, I turn my attention to the Sparkfun Micro OLED breakout… Since I’m using a LilyPad, I don’t have as many pins as a full sized Uno, so I decided to go the I2C route.
The Hookup Guide for this is great. It gives pictures of what I need to do, and goes into detailed explanations of the pros and cons of any decision. I’ve already the LilyPad’s pin marked “-” to the display’s “GND”, “+” to “GDD”, “A4” to “SDI”, and “A5” to “SCK”. (Spoiler: That’s wrong. More on that later, but please don’t use this line as a guide to hooking your LilyPad up to the Micro OLED)
Turning my attention to the solder-bridge jumpers, I need to add a bridge to D1 and D2, set the D/C jumper to 1 (add a bridge for that), leave BS2 alone at 0, and set the BS1 jumper to 1 (remove the existing bridge and add a bridge in the other spot.)
I messed that one up. Big time. Well, maybe not big time… but in my effort to de-solder the BS1 jumper, I burned things beyond usability.
And so, I waited for next payday and ordered myself a new Micro OLED breakout.
The Build, part 2:
As soon as the new display came in the mail, I went to my workbench and successfully de-soldered the BS1 jumper from 0, and added a bridge in its 1 position. I then added the bridge to the D/C jumper to set it to 1.
I snipped the wires off of the dead display, soldered them onto the new display, and attached my LilyPad to my computer via USB. Observed the blinking LED… good feeling. Shoulda done that sooner.
Brought up the Arduino IDE, plugged in a simple Hello World that should have brought up a display on the Micro OLED… nothing.
Scrambled, checked, rechecked… unplugged, replugged… re-uploaded the sketch multiple times… changed variables multiple times…
Then, finally, stumbled onto the pin definitions of the LilyPad. Also, a bit of I2C with different versions of the AtMEGA lines of chips… I learned that A4 and A5 aren’t the right pins to use after all… but that I can use pins 2 (SDA) and 3 (SCL).
At least, in theory.
Shuffled a couple wires around… et voila: a correctly connected connected Sparkfun Micro OLED Breakout and LilyPad Arduino USB.
Plugged in the battery (which I verified works during the scrambling and rechecking from earlier), and was greeted with an unchanged blank screen.
Pulled out the multimeter, black probe to the hunk of amateurishly applied solder on the - pin… red probe to the even uglier hunk of solder on the + pin… Yep, 3.3v, as expected.
And that’s where I am now.
And, writing this out, I’ve realized that I didn’t bridge the D1 and D2 jumper. It’ll be another 3 hours until I can try… but it’s also entirely possible that my desoldering of BS1 was incomplete before I soldered the other jumper position… I’m a bit gun shy in that respect, and that jumper already looks uglier than I want it to, but at the same time, looking at it under a magnifying glass, it seems the bridge has been successfully removed…
Any advice, encouragement, admonitions, warnings, etc., are appreciated.