Moteino R5-USB & FTDIAdapter R2

There is now a new revision of Moteino USB (R5). It has 27ohm resistors on the D+/D- lines and pulled up the RST line on the FT231XS chip which should help with any upload issues, see this forum post for more details.

Also the new FTDI Adapter (R2) fixes the same issue and also switches from FT232RL to FT231XS. The reason being the economics of using a chip that is not only cheaper while doing the same function, but also the one and only USB-serial converter I now use.

I assemble all these boards on a pick and place machine and having a reduced and more efficient BOM makes a big difference. The FT232RL came in a wide 24mm tape which occupied a separate 24mm feeder. Buying a full reel of those parts is an impossibility given the price, and partial reels require a leader to load into the feeder, an extra fee every time you buy anything less than a full reel. Plus, some of the leader tapes I buy from Digikey break off pretty easily and so it’s a pain to work with individual feeders and I’m trying to avoid leader tape whenever I can. The FT231XS come in tubes which makes it much easier to work with using the vibe feeder. The only downside is that I have to reload them more often (58 parts per tube).

Mailbox Notifier Upgrade #3

As I explained in my lipoly+freezing=failure post, I ran into a snag with the brand new Lithium Polymer battery operated MotionMote that serves as my mailbox notifier. It discharges quickly after being exposed to the cold for a while, it seems like below 30F it goes downhill and then falls off the cliff and dies around 24F (-4C). After a recharge the cycle repeats, every time dying a little faster which means cold damages them permanently. So being tired of this nonsense I wanted to give alkalines a try and also wanted to add a WeatherShield to the mailbox, if it’s out there why not report temperature, humidity and pressure as well in addition to telling me when the mail is delivered.

UPDATE: the LiPoly batteries are still working great above freezing and will provide a compact and longer lasting charge than a 3xAAA pack. In the spring time I switch to a LiPoly because it lasts longer and I can charge it directly from the onboard USB of the MotionMote PCB. In the winter I go back to alkalines because they survive in the deep freeze.

The first step was to solder the weather shield on top of the Moteino, only 7 pins are soldered after being raised a little: GND, VIN, 3.3, A7, A5, A4, A3. The bottom of the WeatherShield was insulated with a piece of electrical tape to avoid any shorts.

Then I added the new battery – a 3xAAA holder with older batteries. I needed 3x of them to get above 4V so there’s some head room for the voltage regulator on the Moteino and the PIR sensor which was modified to allow running into much lower voltages. I could have soldered the battery holder wires directly to the MotionMote PCB but I had some spare female JST connectors and I added that to make it easy to remove later if needed. I took the measurements to lasercut another box that will fit this.
With the help of previous box designs I was able to get the dimensions and hole alignments right the first try. The box blueprint is published here for those that might find it useful. Here’s everything after test fitting:

Velcro goes on the back and the Moteino antenna protrudes from a hole in the box through a short cut in the velcro. The wire antenna also goes out the mailbox through a tiny hole. The slots in the side allow air to go in for better humidity readings.
After some minimal coding, the mailbox notifier sketch is altered to do the WeatherShield readings. The new sketch is published in the same repo. The new mailbox is now smarter and it gives all the following readings:

LO:4h1m BAT:4.36v F:3475 H:37 P:29.32

where LO is last open elapsed time,  F is fahrenheit in hundreds (divide by 100), H is humidity in %, and P is atmospheric pressure in inHg. It’s also running happy after being buried in the last winter storm. In the morning when the sun hits the mailbox directly the temperature can rise 20-30 degrees above the real temperature, but otherwise throughout the day it’s pretty stable and comparable to WeatherUnderground, when it’s overcast it’s often within 1 degree of WU but I am aware there are multiple factors that can influence a temperature reading in such a location. Humidity and pressure readings are also very stable and rise very deterministically.

Chinese lithium cells don’t like freezing


The background story
It’s winter again and freezing temps are taking a hard toll on the lithium polymer (aka lithium ion) battery in my mailbox notifier. You’d think the *not-so-cheap-anymore* lithium Ion/Polymer batteries you find on all the online electronics reseller should be fine even at -40C if hobby drones and electric cars like Teslas run on lithium batteries right? Wrong.

I used to have a MotionMote powered by a LiPo in my mailbox and I found that below a certain freezing point the LiPo battery would simply fail and need recharging, and it looks like there is irreversible damage to the cell due to the freezing temps (every cycle it dies it dies faster). Maybe this is an edge case but I don’t think I’m asking much of a LiPo battery to survive Michigan winter, I mean really – half the projects I can think of are outdoors. If you’re able to read through the chinglish datasheets for these LiPos, one thing that you can find is the low temperature operating point is somewhere around -20 to 0C (ex. here or here – look for “Working temperature” it will be -20 – 60C). So basically those are lies and misleading information, nothing unusual from our friends in china who love to sell us junk for what is now a trend of increased prices. These batteries from all US vendors are chinese and fail at between 20-30F (-4C). I bought several from different vendors to verify I don’t have a bad batch. They all fail. What I find intriguing is the guilty silence of the US resellers who promote these batteries. This is meant to break that silence or ignorance: chinese LiPos die in freezing temps!
Just think of all those kickstarters that use lipo batteries, here’s a photo camera that runs on Lipos and you will discover will likely fail when you take it on a fun in the snow day.

I trusted the datasheet and got burned, even sourced a larger batch of these batteries intending to offer along with the MotionMote kit and then realized they fail below freezing when the winter season arrives. I also found that USPS doesn’t ship batteries at all and there is a restriction of 2 batteries (larger than ~750mAh) with UPS and Fedex, a rule broken by at least one of the major US vendors that will I won’t name but I bet you are a customer of, it surprised me. I don’t know what’s the penalty if you get caught shipping more than allowed HAZMAT limits. So I gave up trying to arrange shipping for these cells and instead I will try to make my stuff with alternative power sources in mind, at least for the projects that make a lot of sense to be used outdoors. In fact I think all my projects that have lithium battery JST connectors also have adjacent pins to connect any other power source like AA battery holders if desired.

Of course LiPolys are prefectly fine indoors and will offer a high charge density per volume and are great for MotionMotes and other similar nodes; they are also very popular with hobbyists so I will continue to make boards that support them (boards with chargers), but I will probably never sell them knowing these limitations and given the difficult shipping restrictions.

Fixing my problem
As it turns out alkalines are pretty happy in freezing temps, and in the following post I will show the new upgrade iteration to my mailbox notifier, which not only replaces the battery but enhances it to make it into a weather monitor as well!

November 2014 Updates

Here are some updates and announcements for this month.

  • I released important patches to the RFM69 and WirelessProgramming libraries. Please get latest, these should be addressing some network hanging issues in high traffic/congested networks, and also fix channel shifting for wireless programming. The discussion around this patch is documented in this forum thread. As always, I welcome and encourage constructive dialog and collaboration to fix bugs and improve libraries and examples.
  • I am discontinuing the offering of RFM12B transceivers which are getting old and almost nobody is interested in buying them anymore. I encourage the use of RFM69 transceivers for all new projects and upgrades. Moteinos will continue to have the footprint for soldering of RFM12B transceivers until further notice, so those who want to source their RFM12Bs from another source are welcome to use them on Moteino.
  • There were a bunch of recent posts in the forum complaining about issues with FTDI drivers and or inability to upload code to MoteinoUSBs. Some users have returned their Moteinos but in all cases so far I found the boards completely functional which leads me to believe there is a driver issue on some/all operating systems. I was not able to reproduce any of the issues in several Arduino IDE versions. The driver I have today on Win7x64 is FTDI driver v2.12.0.0 updated via Windows Update.
  • There is a new Moteino core that is very light compared to the previous version. This core contains the definition variants for MoteinoMEGA and the regular Moteino. Once you install this core in your Arduino {Sketches}\hardware folder you will now see two new entries in the Tools>Boards menu (restart required): MoteinoMEGA and Moteino. The new officially suported Arduino version is v1.0.6 (stable). Here are the new options:
  • Moteino and LowPowerLab libraries will soon be integrated at which is a great website based alternative to the Arduino IDE for developing and storing your sketches while enjoying updated libraries and a multitude of other vendor sketches and repositories. It’s very easy to upload your sketch to your board directly from the browser. More on that soon.
  • I am continuing to migrate my PCB designs to ENIG finish which is more costly to manufacture but is lead-free and makes for better and more professional looks of my designs. I hope my customers enjoy and appreciate the better quality at the same low prices.
  • modelrailroadYou can see a cool model railroad project involving Moteino starting at page #92 in this November-2014 edition of Model Railroad Hobbyist Magazine (courtesy of Geoff Bunza). He also posted a well documented tutorial of how to get started with Arduino Mini or Moteino at page #99 in the same edition. Youtube video of the model in action is here.
  • The Moteino-Framework did not make it into the finals of the 2014 Hackaday Prize contest, but it did make it into the top-50 semifinalists out of ~800, and is on place #13 of the semifinalists listing according to community vote ranking at the time of this writing. I felt there was no chance it would make it in top 5 since automation is boring these days (despite the innovations in my entry), and in the end none of the other similar entries made it either. Honestly I was a bit disappointed with the grand prize winner project, I think it’s a cool project but as far as usefulness for the masses of DIYers/hackers I don’t find it very interesting, or maybe I’m the only ignoramus not really interested in launching satellites and depending on people I don’t know to supply me data about my satellite when it flies over their location. But I guess usefulness was not among the judging criteria.
  • As a result of making the top-50 for the Hackaday Prize (semifinalist) I won a $1000 which will be awarded as a credit. I think that’s way better than $1000 worth of uninteresting swag picked by the Hackaday sponsor/staff on the winners behalf. How should I spend this prize? I want to get something memorable like a tool, so I remember I won this prize when I use it. Any suggestions?

October 2014 updates

Maybe not really obvious but a lot of stuff is going on at the humble Low Power Lab. Let me just throw in some announcements and updates:

  • Moteino R4s, MoteinoMEGAs and ATXRaspis are now coming in ENIG gold finish. This is to move towards more professional looking PCBs and to meet RoHs lead-free status. This costs a bunch more to make but instead of raising prices I actually discounted the Moteino options and will do my best to lower prices even more. I am trying hard to keep Moteino a high quality product at an affordable price for makers and businesses alike.
  • I’ve been busy putting together the requirements for my THP entry. The top 5 finalists will be announced around October 13. If Moteino Framework makes it in the finals that would be quite cool, but would put more stress on me to meet the extra criteria required by end of October.

  • One of the things I’m working on is getting a Motion-OLED shield for Moteino ready for production. Here’s a peek of it:
  • I’ve been having a blast with my new pick and place. I am transitioning all my designs to panels and adding fiducials for vision correction. I can’t help but mention that there’s a world of difference between professional machines and “DIY Open Source” type of machine that are just toys. Before getting my assembly equipment, I was doing manual assembly with a $20 modified aquarium pump and reflowing in a slightly enhanced toaster oven. Other than me physically being there I still think my previous methods were better and more productive than a lot of these makeshift pick’n’places.

    Something tells me that people are fascinated with “DIY open source pick and place machines and 3D printers” and other not really “connected” devices which was the main point of the Hackaday Prize contest. I know exactly why we’ve not seen even one such successful Pick’n’Place project, not even close, and my prediction is we will not see one too soon either based on my experience with a real one. I will expand on that more extensively in a future Pick and Place article.

  • There is a new revision of PowerShield, mostly PCB changes and making stuff more obvious to understand and use: