Perpetual Thrill

Here is the current setup, wherein I am attempting to isolate the sensor and microcontroller from the computer with a midi breakout board and a midi box on the other end. The theory is that since midi is optically isolated by contract the computer’s noisy ground plane will no longer be a problem.

Unfortunately, this did not work. Apparently, the length of the midi cable itself acts as enough of an antenna to introduce noise into the system (!). When the cable is plugged in, the ECG board will not read, and when unplugged it picks up my heartbeat just fine. Maddening, yes, but at this point also borderline hilarious.

I would try optically isolating the Olimex board’s serial port, but it is hardwired to 115200 baud, which is faster than any optical isolators support. Instead, I am going to try this weird-ass digital isolator chip. The datasheet says it is capable of 2mbps data transmission, which is more than enough.