Arduino based oximeter

Time background: Mid-December:
After the full liberalization, "Yang Guo", "Yang Kang", "Wang Chongyang", etc. appeared in the arena one after another. The oximeter, an artifact of the arena, was sold to "sky-high prices" (several times the usual price) by some merchants. When my dad was about to buy an oximeter, I immediately stopped him and angrily scolded him for spending a huge sum of 4.77+4.27 to buy the module and dug out the Arduino NANO that was packed at the bottom of the box.
Showing off my electronic CV engineer style, I searched for a copy of the code from Station B [Nanny Level Tutorial] Arduino Oximeter Tutorial that even a monkey can learn, and make it yourself from scratch! _bilibili_bilibili
measurement results are almost consistent with the data of the bracelet
. Note! ! !
Notice! !
Notice!
Do not shake your body during measurement, otherwise the data will soar.