Weekly Update: March 25, 2017

Ah! I’m late! Totally forgot to write this on Friday, then yesterday had a few things crop up and didn’t have the time.

Anyway, what have I learned in the past week? Well, for one, of the four ESP8266 modules that I had bricked, none of them actually were. As it turned out, I had the wires to the screen in such a way that they were causing it to not start properly. Changing the wires (And the PCB itself) fixed that issue, so now I have four working ESP8266 prototypes!

This DID lead to an important lesson: The ADC on the ESP8266 only reads in on 0-1v, give or take. The boards I had used had built-in voltage dividers which I had missed. Thankfully, I spotted this after the Feather Huzzah I got ended up with weird readings. So, now the V3 has the appropriate voltage dividers. While I was thinking about resistors, I went and double checked – Turns out, I had also missed the I2C pullup resistors, so those have been added in as well

I also posted the preliminary files for the V3 onto GitHub. They’re a bit sparse, since they’re not finished, but if you want to toss code at me or point out circuit board flaws, I’m perfectly fine with that. In fact, MintShard on Discord pointed out a potential issue with the battery ADC – As it’s continually monitoring the battery voltage, the ADC pin will be out of spec with a much higher voltage than it should have when the device is off. To test this, I finally got around to purchasing a benchtop power supply along with some breakout boards and ADCs to test. I’ll figure out the breaking point for these things, and see if I have to modify the design of the circuit board to compensate.

I’ve also started the order for the first prototype circuit boards. Those should be here early next week, and at that point I’ll be able to put together and test the V3 design. If all goes well, it’ll work. But as the V2 and V1 have shown, all rarely goes well the first time.

On Saturday I’ll be putting up the results of the ADC testing, along with whatever else I manage to do this week. I’ll be honest, while there is still stuff I can do with the programming, a lot depends on the circuit board, so I’ve been playing a bit of Mass Effect: Andromeda lately.

As always,  feel free to join us on Discord, on Twitter, or on Facebook – See you next week!

Weekly Update: March 18, 2017

Greetings everyone!

Welcome to this week’s update. Like last week, it’ll be pretty short, since much of what I accomplished was destruction. What type of destruction? Well, three ESP 8266 boards in the span of just a few days.

The first one I managed to toast when trying to measure the power usage. I also learned that the multimeter I have for this doesn’t do it very well, so I’ll be looking into something to measure better. This happened on Monday evening, so I overnight shipped two replacements – A WEMOS D1 Mini, a bit smaller than the nodeMCU design I was using, and one identical to the design I had.

On Tuesday, a wonderful snow and ice storm rolled in and caused problems. I was out of power for most of the day (Not that I could fiddle with the prototype anyway, since I fried the board), and the shipments were delayed. Instead of getting them Wednesday, I got one on Thursday and one on Friday. I spent some time on Wednesday poking through packaging options (More on that later), and when I got the D1 Mini on Thursday, I set about making sure it worked properly.

Fantastic! It did! But the on-board voltage regulator wasn’t that grand, and the screen was having some issues. So I tried to supplement it with the breadboard power supply I have… Less than an hour after opening the box, I had managed to fry the board again. ESP8266 devices are really sensitive to higher voltages – I hadn’t connected the 5v to the 3.3v line, but apparently in the process of plugging things in I caused a spike of sufficient power to kill it. Oops.

Friday comes along, I get an absurdly large envelope for the nodeMCU board. I know this board decently well by now, so I plug it in, upload the sketch, and then plug it in to the breadboard. At this point in time, it’s dead. I honestly have little idea what could have caused this, but the serial monitor repeatedly showed the same fatal exception issue, which is unrecoverable as far as I can tell.

So later today I’ll be going down to MicroCenter and picking up an Adafruit HUZZAH feather board. Hopefully I won’t fry this one. I’m glad that I’m using two AAA batteries and boosting the power, though. Unboosted, the power still falls easily between the 1.7v and 3.6v that the ESP8266 requires, and boosted it’s at the safe level of 3.3v. There will be a “Raw” input, but that’s for hackers and if you fry the board that way, then that’s not my fault.

I mentioned packaging earlier, and while I’m not going to delve into specifics, it’s a lot cheaper than I expected. Things are likely to change, but it’s pretty simple so far. No custom molded interior, sadly, but the box will be tight enough, and the anti-static foam should keep them secure and stable.

The question I have now is with lanyards. I’ve previously found the most inexpensive lanyards I could get my hands on, and I have not exactly been pleased with them. They have a tendency to fray, and they also look cheap, which is not a good thing. I have the option of looking into higher-quality lanyards, which may or may not affect the price, custom lanyards, which would either be sold separately or would definitely affect the price if included, or simply not have a lanyard option.

You can leave your feedback via a comment here, on Discord, on Twitter, or on Facebook. And, as always, you’re welcome to join our discussions at any of those locations.

Weekly Update: March 11, 2017

Greetings, and welcome to another Weekly Update!

This one is going to be fairly short, as, well, not much has happened this week. I’ve have what should be an initial prototype design for the V3, but I have to test to make sure certain parts function like I expect them to function. I have a handful of screens and some PCBs for testing them on the way, along with a screen breakout from Adafruit for more practical experimenting. The screen that I ended up settling on is a 2.2″ screen, which you can purchase from Adafruit here, with a 320×240 resolution. It’s smaller than the 2.8″ I was hoping to use, but this is something the manufacturer can actually get their hands on – And for a decent price.

The new screen is a little larger than the PCB size of the Version 2, with the screen being 55mm x 40mm and the V2 being 53mm by 40mm. This pushes the V3 to a larger size – Which is actually a good thing, as it makes the images a bit bigger and easier to see. The preliminary size for the V3 is roughly 68mm by 47mm – 13mm wider and 7mm taller, being 3196 mm2 compared to the 2120 mm2 for the V2. Roughly a 51% increase in surface area. This has made my life a lot easier with placement of parts – There’s a decent amount of room to wiggle things around on.

I’ve also looked further into packaging, and have had some success. For the low volume we do, 100% custom packaging is out of the question, but there are definitely some alternatives we’re looking into.

Hopefully by next week I’ll have some news to report on the new screen. As always, feel free to join us on Discord, on Twitter, or on Facebook. See you next week!

Weekly Update: March 4, 2017

Greetings, and welcome to another Weekly Update. This one is a little later than I wanted, as I picked up a few extra hours at my main job and didn’t get the chance to write it yesterday or today.

I’ve had most of the prices returned for the parts I need for the V3. I can confidently say that the price for the V3 will be no less than $25, which brings me to my next point: The screen. The manufacturer CAN source the screen – For a cost far greater than I would pay for it. I’m not going to go into details, but the cost per screen is more than the entire cost of parts for a V2. Obviously, that won’t fly. I can find sources for them for significantly less, but that would mean either hand-soldering on all of the screens, or waiting for them to get here from China, just to ship them back to a different part of China.

So, I’ve gone investigating a different route: I sent them a different screen to look into – And this one is a bit larger. It’s a 2.8″ screen, and I think it’s close to double the size of the 1.8″ screen. This would be more expensive than the 1.8″ screen, but if they can source it for a reasonable price, it would make for an improvement in screen size. If this screen is sourced, I can say the V3 would likely be about $30 after additional cost for the screen and other equipment is taken into account.

As far as packaging goes, I heard back from one of the companies I inquired to, and their equipment and products are completely wrong for the job. They design for large, heavy parts – Like automotive equipment. The V3 is neither large, nor heavy. I’ll continue looking into what I can find.

Until next week!