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README.md

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 # MAX30102_by_RF
 Arduino C code for MAX30102 pulse oximetry sensor (MAXIM Integrated, Inc.)
+
+This project originated from a public domain reference design MAXREFDES117# published by Maxim Integrated, Inc., at
+https://www.maximintegrated.com/en/design/reference-design-center/system-board/6300.html/tb_tab0
+for the System Board 6300 containing MAX30102 sensor for pulse oximetry. I adopted it to work with Adafruit Feather M0 Adalogger (https://www.adafruit.com/product/2796).
+First, I copied the firmware code for Arduino platform from that page, then I heavily modified it making the following changes:
+
+1. All the original I2C calls in max30102.cpp that relied on platform-dependent SoftI2C library have been replaced by their equivalents from the generic Wire library. Consequently, SoftI2CMaster.h header file was no longer needed and has been removed.
+2. Unnecessary Adafruit_NeoPixel.h and Adafruit_NeoPixel.cpp files have been removed.
+3. A software bug in maxim_heart_rate_and_oxygen_saturation() function in algorithm.cpp has been fixed: after applying 4-point moving average, the an_x[] still contained original last three points (an_x[97], an_x[98], an_x[99]). Subsequent code still referred to the full an_x[] array (0-99) instead of its averaged portion (0-96).
+4. In algorithm.h the "uint8_t uch_spo2_table[184]" has been replaced by "float uch_spo2_table[184]", where the original integers have been recalculated into floating point numbers with 6 decimal digits precision.
+5. A completely new algorithm of signal processing and resulting heart rate and SpO2 calculation has been designed and placed in new files algorithm_by_RF.h and algorithm_by_RF.cpp. The algorithm has been described and published in the following Instructable: ().
+6. The RD117_ARDUINO.ino file has been rewritten from the ground up. Code for saving oximetry data to an SD card has been added, algorithm_by_RF has been made default, while Maxim's algorithm has been made optional. Integer variables were replaced by floating point variables, where applicable.