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.

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

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!

Using Android Devices in Machine to Machine Communication

Would it be great to make your android device do something even when you are away from it? Or may be let it ring to let you find it with the use of another phone? This process is somewhat or maybe it is a full machine-to-machine communication application which is widely used in so many industrial applications today. 

Just recently, a lot of parents are very much concern with the whereabouts of their kids so they are forced to buy another security device to let them achieve this but these devices are often expensive and requires extra contract with the telcos to ensure reliability.

Nowadays, a lot of inexpensive android smartphones equipped with the latest OS and hardware but the only thing missing is a reliable app that would make these smartphones high tech device. So I thought I should create a simple app that screens incoming sms messages. If this app is able to receive a certain code which in this case is "Hello", it will automatically launch the camera app to take picture and display the thumb nail on the screen. This is just a demo program just to test whether my idea of making the android device do something even when you are away from it.

And I would suggest that this app can be enhanced further by adding Bluetooth communication with HM10 to control other devices in the house with so much ease. You may check my previous post here: More Fun with HM 10

You may download the source of the app here: https://drive.google.com/open?id=0B1tuk2j-arZSNVZfdEcwVUZha0U

If I will have the time, I may combine the 2 apps.

OPENCV on Python on my WIndows 8.1 tablet

I have just installed OPENCV on Python on my WIndows 8.1 tablet and I have been playing with it like crazy. Opencv is a powerful tool to programmatically manipulate an image. It is like a low level version of Photoshop. And what happens when a programmer gets to programmaticaly manipulate an image? The possibilities are endless.

I had skipped the "hello world" part because I am not new to opencv and here is what I have tried to develop as part of my learning: finding the exact location of a small image taken from a larger image.

This ois the large image:

And obviously this is the small piece of image:



 And here is the result:

 

 

And here is the python code I used:

# import the necessary packages
import numpy as np
import cv2

# load the big_image  and small_image  images
big_image = cv2.imread('C:\\Users\\mybook\\Documents\\alpha.jpg')
small_image = cv2.imread('C:\\Users\\mybook\\Documents\\piece.jpg')
(small_imageHeight, small_imageWidth) = small_image.shape[:2]

# find the small_image in the big_image
result = cv2.matchTemplate(big_image, small_image, cv2.TM_CCOEFF)
(_, _, minLoc, maxLoc) = cv2.minMaxLoc(result)

# grab the bounding box of small_image  and extract it from
# the big image
topLeft = maxLoc
botRight = (topLeft[0] + small_imageWidth, topLeft[1] + small_imageHeight)
roi = big_image[topLeft[1]:botRight[1], topLeft[0]:botRight[0]]

# construct a darkened transparent 'layer' to darken everything
# in the big_image except for small_image
mask = np.zeros(big_image.shape, dtype = "uint8")
big_image = cv2.addWeighted(big_image, 0.25, mask, 0.75, 0)

# put the original small_image  back in the image so that it is
# 'brighter' than the rest of the image
big_image[topLeft[1]:botRight[1], topLeft[0]:botRight[0]] = roi

# display the images
cv2.imshow("Big_Image", big_image)
cv2.imshow("Small_Image", small_image)
cv2.waitKey(0)

This may a simple app but it can be useful for game development, or it even be further developed and improved to create an image search engine.

Using my Windows 8.1 Tablet Pc as Raspberry Pi 2 Model B Monitor

The raspberry pi is a tiny pc running on linux based operating system with gpio pins. It is like having an arduino and a personal computer. Unfortunately, the rpi does not have a builtin screen and having to connect it on a huge monitor does not make it a tiny pc anymore. But more recently, I discovered that I can use my Windows 8.1 tablet as my rpi's monitor and take note, the connection is over wifi.

With this configuration, I can access my rpi anywhere even when I will just leave it at home. To access the rpi from my tablet, I used xming and putty. Both software can be downloaded free of charge from the internet. It only took me a few minutes to figure out how to make it work, thanks to those numerous how-to guides on youtube. Without them my mini project would have never been possible.

Here is my setup:

 

So now, I can some python programming with image processing usin my raspberry pi and the wimdows 8.1 tablet pc during my spare time at work.

A Desktop CNC is almost an all-in-one Machine

I have always been dreaming of a machine that can do almost anything I want it to do. For example, I want a fried chicken so all I have to do is put a live chicken into the machine and 1 minute later, it comes out as a perfectly cooked fried chicken. But of course this machine is still light years away from becoming a reality. But as an electronic hobbyist,this machine is almost a reality when it comes to creating an electronic device and this is the Desktop CNC Milling Machine.

The cnc machine can enable me to create a small fully functioning electronic device faster using the materials of my choice. For example, I need to create a robotic gripper, if I dont have this machine with me, I will have to take my file to a laser cutting service provider but it is very seldom that the service is reliable I had found one but they are very far and will not respond to emails which means I will have to go there personally to transact business and that still depends on the availability of their machines and another disadvantage is it will be a lot more expensive not to mention that the material is limited to acryllic. What if I want to use aluminum so the robotic gripper will never become a reality. And what if I made a simple error or need to do small adjustments? It can be worse if I am going to create devices that involves pcb. I really dont like the idea of using Ferric Chloride to get good results.