Now that I have the working breakout board for the TLC59282, I was able to get the software working and get it tested pretty quickly. I did have one minor wiring problem that was just due to the way I’ve got my breadboard setup, but after I fixed that, everything worked as I expected. This chip is WAY easier to use than the TLC5940!

In the process of setting up the SPI, I did discover another problem with the boards I had ordered. Turns out the Slave Select line is on the same pin as my IR in for the remote control, but in order for SPI to work correctly, this pin needs to be kept low. So, in order to move the pin, I first looked at my board layout to see if I could move it to a pin closer to the IR and make the layout easier. I read a post (on reddit I think) where someone said they do the planned PCB layout first, before the schematic, so they have a better idea of how to hook things up to make the layout easier. I should have done that, or at least looked for some optimizations, but it’s no big deal. I’ll remember to do that next time as I was able to find some trivial changes to the circuit that made the layout easy. The schematic now looks like this:

New schematic based on changes I discovered while prototyping on the Arduino

I did get everything prototyped out, including the LED controller, hall effect sensor, and IR input. I verified they all worked together, the hall effect sensor worked on the new interrupt pin (which I’m hoping works better than a PCINT I was using on the previous version), and the IR works with everything else running. I also did a bunch of speed tests. I’m able to run the SPI at 8 MHz and wanted to see if that was fast enough to keep up with the spinning board. From the tests I’ve done, it looks like it will be more than enough!

Breadboarded version of the SpinnerHD to test the TLC59282 and make sure everything works like I expect.

And here’s the code I used to test the prototype.

Last night a little after 7 pm, I got email from OSH Park that my boards were back from fab and by 9:30, email that my boards had been shipped! Fantastic news since I am hoping to get them before President’s Day so I can populate them on my day off work.

On Thursday, I got the headers I needed to use the breakout boards for the TLC59282. This morning, I finally got a chance to put them on. As it turns out, the headers I ordered aren’t quite what I wanted–they are double sided, so the pins are the same length on each side. They will still work though and were quick and easy to get soldered on:

My breakout board mounted on a breadboard

So finally I can get to prototyping and working on the software. I used the same breadboard I had when using the TLC5940 earlier because it already had a bunch of LEDs on it. Everything was good up until the point where I realized the LEDs were hooked between the chip and VCC, not the chip and GND. Took a quick look at the datasheet and then at my schematic and realized I did wrong. In my schematic, I have the common side all to GND, not VCC. At first I thought I could work around this by cutting the traces to GND and fix them to go to VCC. Then I remembered that I did a GND fill, so I don’t have just one or two traces to cut total and one new wire to VCC, but three traces for each LED and adding new wire hacks (grr–why can’t I remember the real name of these wires right now?) to each LED.

So, in other words, the boards are pretty much DOA. They aren’t completely useless. I’ll still get to use them to test the balance, make sure all the drill holes and everything else was manufactured as expected, and photograph to use as the banner for this blog. I did actually expect that this first board probably would have issues that would make it not work. I was expecting those problems to be manufacturing issues I didn’t know about though, and not my own stupid errors. As I mentioned in a previous entry, I did know I was risking this by ordering the boards by prototyping, but it’s still disappointing.

Now this post does make it sound like I’m pretty rash and impulsive, making many mistakes. Can’t argue with you there. I knew the risks though and it’s not that big of a deal–just another week or two delay. This time I’ll get everything prototyped before I order the next board.

The breakout boards I ordered from adafruit arrived today. As soon as I could, I soldered on a TLC29282 so I could breadboard it and start testing it and writing the software for the spinner. Turns out it is kinda difficult to solder at this pitch. Although, I don’t think my soldering iron is working very well either. I accidentally left it on for several days one time and now it feels a little different. As I was testing that I hadn’t left any solder bridges, it suddenly occurred to me that I didn’t have any of the headers I needed to actually use this:

So, now it’s a couple more days while I wait for headers to show up in the mail… 🙁