I had shelved this project for lack of time after starting a new career in another country, but I recently got a text from a friend of mine telling me his heart was acting up, and he wanted a logger to what was going on.
So I'm picking up this project again, and for extra learning, I'm changing the scope a bit.
- I'm scrapping the bluetooth connectivity
- I'm optimizing for power efficiency
- I'm moving away from the hand solderability to standard reflow pads
- The device will only log short intervals of data upon request from the user
I'll also do the following changes
- Shorten the electrode leads as much as possible
- Scrap the SD card and implement a USB mass storage device coupled with an external flash IC
- Switch to the STM32 platform
So I've already got the analog front end working adequately. Now I will make a test PCB for the MCU and flash IC setup, and get the mass storage working.
I'll use this source as a guide:
The MCU will be a STM32L412xx. Off we go!