EEMB LiPo Battery

It has been a couple of days since the last post. I have been out of town, but it is Sunday now, and I’m here to provide you this well-deserved update.

I have continued working on the retro watch app, which is my first app written in C on the XIAO Expansion Board. This is also the first Arduino project I have attempted in several years.

So for this project, I thought it would be cool to get a LiPo battery so it can run wirelessly – a fairly important feature for a watch application. I purchased this EEMB LiPo battery depicted (LP603449) mostly because it was cheap and was 1100mAh. It is obviously too big for a watch, but I expect to use it in other projects as well. And let’s be honest, I’m not making a watch; it is an educational and nostalgic endeavor.

Here is something I learned. There is no standard established for the polarity of the connections to the JST connector on the end of this battery. The expected connections were reversed on the XIAO Expansion Board, so I had to swap the connections on the male end. Fortunately, the polarity was clearly marked on the Expansion Board, which helped me spot the issue immediately. Per Google, this is a very common situation encountered in the prototyping space, but it was news to me.

The Watch App

The watch app fires up and immediately connects to a local network to retrieve the NTP time. It then updates the onboard RTC with the time. The watch then runs as watches typically do, updating second and minute bar indicators at the bottom of the screen every second. The Date function needs some work. I am presently unable to retrieve the current date with the libraries I am using and will investigate further to resolve. Every 30 minutes, at the top and bottom of the hour, an audible sound is generated to indicate the status. Pressing the button on the Expansion Board toggles the display between a 12-hour AM/PM time format and a 24-hour military time format. I ran this overnight on battery power. There were no issues. I am also using a loaded font for the time which is a feature i was looking forward to implementing. The default font is ok, but looks blocky when enlarged on the OLED. The Adafruit GFX font library is a keeper.

Parting Thoughts

So, what do I think of the battery? It is too early to say. It works. It charged up fine. I’m not an expert on battery testing, but I will provide an update if I encounter any issues.