Friday, April 29, 2016

MAX30102 Heartbeat Sensor and Oximeter

A very common but most likely the most important feature of smartwatches that should make them useful and separates them from ordinary watches is the inclusion of sensors that measure rate of heart beat and blood oxygen level. I am not a health professional but as an ordinary folk, the data could be important. For example I could use the data make the color of the watch's screen respond to changes in my heartbeat patterns.

And again, while I was searching for simple circuits that I can use for my DiY Smartwatch, I was able to find the MAX30102 Heartbeat Sensor and Oximeter which I believe some of its variants were used in Samsung latest flagship smartphones. Below is its sample schematic diagram:

This can be a premium alternative to the one I found on ebay, a sparkfun clone product but very cost effective and working:
And with the schematic at hand, I could use thinner pcb and integrate other watch stuff like the rtc in one pcb which could make the watch thinner. The downside is since it will be developed from scratch, prototyping will be more difficult.

Thursday, April 28, 2016

Update on my DiY Smartwatch Project

Recently, I had been slowly researching for new add-ons for my SmartWatch Project. And here are the things I have in possession for the project:

1. I have 3d Printed the watch bezel and the result is very promising see picture below:

2. 6DOF MPU-6050 Module 3 Axis Gyroscope+Accelerometer,  Heart beat sensor and ESP-03 wifi module has arrived:

3. The 1.44" touch panel has arrived as well:
The hunt for touch panel was not an easy task. I have searched all over Metro Manila and I could not find this precious component, I have searched ebay, and nobody sells this item, so I tried alibaba there were some who sells similar product but too expensive and so I decided to buy a 1.44" lcd with touch panel and luckily, I was able to buy 7pcs at $10/pc + $30 shipping and $20 customs duties. I have chosen the 4-wire touch panel because Adafruit already has an existing arduino library so it would be easy to implement.

I also currently ask a pcb designer to do the rtc pcb design and currently, I have asked them to use 0201 packaging for all resistors and capacitors so that the whole module would fit into 8mmx8mm pcb and the initial design is here:
So far the rtc pcb design project cost is $35. I would have to order all parts from abroad including the pcb fabrication and the prototyping may cost over $100+ because if I order from digikey, shipping cost is pegged at $40 minimum.

see related article: Hacking the 1.44" TFT LCD for my Smart Watch Project

Wednesday, April 20, 2016

CynBet EnerchipRTC is a Great Product for the DIYers

Space is so precious when designing an electronic gadget. Electronics Designers always looking for small components that would perform a whole task if not the major task. Another advantage of being small is that it consumes less energy.

I for one is constantly looking for small electronic components for my numerous DIY personal project and recently, I found the Cymbet Enerchip RTC which is a rtc(real time clock), battery, power management circuit packaged in 5mm x 5mm integrated chip(qfn) package. By the way, Cymbet is the supplier of Google Glass' battery requirements.

Although it is very small, I wonder why they did not included a 32kHz crystal, but having a builtin battery is more than enough to catch my attention. The chip came in 3 variant but personally, I prefer the CBC34803 because it uses I2C communication protocol and lasts up to 120hrs. Here is a typical circuit diagram of this chip:
Another nice feature of this system on chip is that if you are designing your own chip, the company also sells some of their products in wafer form, so like if you want to create your own arduino with builtin power supply can be possible, well who knows, maybe? LOL!