It's been a weird week for me but I think it's time to get back to work on this project with some of my down time. Recently I've been looking into battery management for this project. In the previous revision battery management was handled entirely as a subsystem with very little input from the micro controller. While I still like the idea of the battery management system running semi-autonomously it often resulted in the entire watch shutting down prematurely or failing to easily recover from UVLO. 

My goal for the battery management system in the next revision of this project is to have the entire system controlled (in some manner) by the ESP32 on board. Additionally proper battery monitoring would be useful, currently battery voltage is measured directly by the ESP32 ADC which is only an approximate measure of charge state. 

I've been looking at battery monitors and I'm planning on using the MAX17048 to track the battery and control the power management circuitry. The primary advantage to the MAX17048 is that it allows the ESP32 to accurately read the battery percentage over I2C and thus control the battery management circuitry. It also allows for the undervoltage threshold to be configured which is a great advantage. Overall i'm looking to have full control of the battery management system, preventing the issues encountered with the previous revision that would result in power circuitry disallowing proper startup. 

As for the display I've decided to ditch the LCD module altogether and go with something a bit more proper (albiet more involved to program). For the next revision I'm planning on using the New haven display NHD-1.8-128160EF-CTXI#-T which has a touch screen resistive pannel already on the LCD and is practically the only good touch screen I could find at this size. This display uses a hotbar connection, which saves the bulk of another connector and should make the connection fairly strong. However ditching the module means that I also needed to pick out a seperate resistive touch controller (also on the i2c bus), I'm using the TSC2003IPWR for this but may end up changing that depending on board space requirements. Another adantage is that this new display uses an 8-bit parallel interface, meaning that the overall time required to write to the screen should be reduced by an order of magnitude. I'm looking forward to the capabilities this screen will allow, but it won't be the easiest thing to interface with.

At the moment I'm nearly ready to move into laying out the board, just want to give everything a 3rd look-over before ordering any boards or components. I'll make another log soon about the finalized schematic. 

See you in the next log.