MAX30100 points: Pandemic interval and the entire world is working in the direction of its treatment & precautionary measures. The pastime electronics world is not any exception for that matter.
Earlier it was the hands-free utility units after which immediately the phrase – oximeter got here into being! Even some massive firms offered particular person pulse oximeter free to their workers for a free check-up at dwelling for blood oxygen degree. I additionally bought one button cell operated pulse oximeter for a hefty INR:2000. Then immediately the digital markets acquired flooded with the heartbeat oximeter probe MAX30100 for as little as INR:250 to USD2 a chunk. I bought a couple of from Indian on-line shops however I couldn’t set the probes into work. Even after sensing the probe efficiently the readings have been awfully fallacious!
After having learn the datasheet of MAX30100 and a handful of stories from the Web, I got here to know that these flooded Chinese language oximeters have two points – 1.eight volt regulator points & the I2C pull-down resistance connection challenge. That is an I2C infrared measuring machine. Ideally, the board ought to have an working voltage of three.3V for the infrared LED driver and 1.8V for the management & measurement circuitry however that doesn’t remedy all the issues. The I2C & the Interrupter pin have to be pulled up by means of 4.7K resistor to the three.Three volt as an alternative of 1.eight volts, in any other case they won’t work with the I2C bus of Arduino or the ESP32 MCUs.
The MAX30100 has a temperature sensing provision inside, for oxygen correction but it surely can’t be taken out for measurement functions and the sensor has a power-down sleep state which isn’t utilized by the favored pastime electronics world – why?
Rigging the MAX30100
With a multimeter if you happen to measure the voltage on both facet of the three legs [65K9] regulator, you’re going to get 3.Three volts and 1.eight volts. To this point so good. The three resistors 4.7K  are from SCL, SDA & INT to the constructive bus [1.8 volts] , this really prevents to get the right measurements for this machine, despite the fact that it reveals “efficiently initialized oximeter”.
What we now have to do is take away these resistors and get them one-end linked to three.Three volts as an alternative of 1.eight volts. For attaining that feat see on the board fastidiously. Lower the small observe between the purpose marked  after which be a part of a jumper wire between the center leg and the highest of the final resistor. Use small single strand good high quality wire. Since this place can be in contact of the physique components, they have to be of fine high quality and easy wire.
The MCU we used is ESP32. The Oximeter MAX30100 is linked on the I2C port of the ESP32 and the DS18B20 which is a digital temperature probe & whose digital sign pin is linked to GPIO15 of the ESP32. The probe measures pulse – oxygen degree and temperature from the linked finger after which uploads to a cloud at thingspeak.com website.
The ESP32 has been supplied with a number of wifi id and password. It would hook up with which ever is on the market at that second. The LED linked on GPIO12 is to offer a sign which can blink for a short interval to mark that the information has been uploaded to the cloud server at thingspeak.com. After importing information, the MCU will go to deep sleep mode for 20 seconds after which it is going to get up and do it throughout. Throughout sleep mode the IR led of the MAX30100 sensor may even turn into off and the overall energy consumption will go right down to 4.2 mA and through energetic stage the present turns into 160 mA. On a to protect battery energy. On a 26650, [3.7 volt 3000 mAH] Li-Ion battery this anticipated to run for couple of weeks non cease.
Checks: Whereas placing the finger or the wrist on the sensor , be sure that the physique half space is clear and with out oil, ink or grease. It’s higher to wash it with some spirit. In case the physique contact will not be excellent, then the machine will dangle. To keep away from that scenario, the MCU will restart after 25 seconds from right here. In case the web ,although linked however not capable of ship the information to the web site [“Error on HTTP request”], the MCU will restart.
ESP32 MCU = USD 5 / INR 450
MAX30100 = USD 3 / INR 250
DS18B20 = USD 1 / INR 100
Dimension 18650, 3000 mAh , Li-Ion battery = USD 2 / INR 660
LED, Resistor & energy provide additional.
Whole = USD 11 / INR 1460 [approx]
Nicely, this is quite common right this moment. Simply open an account [free] in thingspeak.com. Get the write key after which change the identical within the sketch with your personal key. The HTTP GET command really open the browser and write the information into the cloud account. Do it by yourself or learn their HOWTOs on the web.