Hi everyone,
In my city I could only find this heart rate sensor and bought it, the problem now is that I cannot find information on how to connect it anywhere, the output pins it has do not correspond to the AD8232. Anyone who has used it who knows how it works?
if you do a web search for keyes MD-344 HL8038 you will find some links
Yes, I did an extensive search, but the only thing that appears are publications from online stores
You may want to start with the data sheet for the 8232. What you have is just a module using that chip, one of several modules available.
Here is a similar example of an 8232 module, similar to what you have. You may wish to read the supporting documents in that link.
Ron
No idea, try some of the links here for Keyes HMD-344
https://www.google.com/search?q=keyes+hmd-344&tbm=isch&ved=2ahUKEwjv8pCXlZHsAhXEHN8KHTAQB0IQ2-cCegQIABAA&oq=keyes+hmd-344&gs_lcp=CgNpbWcQAzoCCAA6BQgAELEDOgQIABBDOgcIABCxAxBDUOH6L1jK8DBgifMwaAVwAHgCgAGAAYgBpgySAQQxOS4zmAEAoAEBqgELZ3dzLXdpei1pbWewAQDAAQE&sclient=img&ei=S6B0X6-hD8S5_AawoJyQBA
I already looked and I can't even find the datasheet of the ic, the datasheet of an ic8038 appears and it is not even the same number of pins, I found a schematic but very blurry and the pins do not match anything with the ad8232
This seller warmly invites you to post your questions, or to contact them.
Please do not hesitate to contact us if you require further information regarding the modules operation.
Try it!
Post #3 I gave you a link to the 8232 Single-Lead, Heart Rate Monitor Front End data sheet? I also gave you another link. Have you tried those links?
Ron
Yes, I had already tried with both links, the 8232 data sheet are different, the ones integrated in the pin configuration, in the example it is also different because of the sparkfun module connections
Ron_Blain:
Post #3 I gave you a link to the 8232 Single-Lead, Heart Rate Monitor Front End data sheet? I also gave you another link. Have you tried those links?Ron
Found other Keyes modules but can't find yours. I can see the frustration in this. 
Ron
I learned that when I see shiny electronic toy to hook to an ESP32, I look, before ordering, for the items documentation and then, I read the documentation to see if I can figure out how to use the shiny-shiny item, before I buy the item. Too many times have I ordered the shiny shiny thing and there be no paper work.
Another lesson learned.
Idahowalker:
I learned that when I see shiny electronic toy to hook to an ESP32, I look, before ordering, for the items documentation and then, I read the documentation to see if I can figure out how to use the shiny-shiny item, before I buy the item. Too many times have I ordered the shiny shiny thing and there be no paper work.Another lesson learned.
If I am not mistaken this part has come up before and a good number of those trying to use it were plagued with noise. Apparently it is not easy to get the pads on just right to get a good signal. I don't recall which modules? During a Google Quest I did see a few Arduino examples which just used one signal. With a scope on hand I would power it and probe the pins and see what I had but less a scope it's purely a guess. I absolutely agree it's nice to know what will be in the box before the box is on your doorstep. 
Ron
