Hi, I am really new here, and I have a project which is a pulse oxymeter and I am using TCRT5000 which is a IR led and photo transistor in a leaded package, and I also use an RED led for the SpO2 acquisition, I already manage to have a decent output for my heartrate using the 'FreqMeasure' library and now I'm stuck with the SpO2, I dont have great background and foundation with arduino so bear with me. I just want to ask some help with the codes/ algorithms for this parameter please. Hoping for your good advices it would really be a big help. Based on some articles that I read, Ratio = (log((ACred+DCred)/(DCred)))/(log((ACir+DCir)/(DCir))) and after getting the ratio SpO2 can be solved by this formula S = 110-25*R and there are also some with R/IR = (ACr/DCr)/(ACir/DCir). but the problem is I don't know much how to formulate my own codes, tho I constructed a code for simultaneous ON & OFF of the red and ir LED's, I have no idea what to do next how do I acquire those datas' to solve those formulas above?. In dire need of help. Thank you!
Why not use an MAX30100? That is optimized for that precise purpose, and will do a better job than a general purpose color sensor...
how I wish I could use a module, but unfortunately my professor requires us to use tcrt5000 and doesn't allow us to use any module, we are even asked to build the circuit on our own. 
he gives strict instructions and yet teach us how the process goes, he just provide us the schematic.