Hi,
I've been having difficulty getting a heart rate signal from the AFE4400 and the NJL5310R/SFH7050 sensors (there is black tape around the sensor isolating it from the PCB). It rarely works on the finger tip, even in perfectly still, perfect coverage of the finger on the sensor with different types of pressures applied by the finger tip, and never works on the wrist. This is an example of what the signal from the finger tip looks like most of the time on the finger tip:
These are the register values used in the initialization:
AFE4400Write(CONTROL0, (uint32_t) B1010); // reset registers and clear timers // Transimpeadance Amplifier Parameters (See pg. 24-26) AFE4400Write(TIA_AMB_GAIN, 0); // Tri-State SPI, Push-Pull Driver AFE4400Write(CONTROL2,(1L << 17) | (1L << 11) | (1L << 8)); // LED Current long drive_led1 = (long) (5.0 / 50.0 * 256.0); long drive_led2 = (long) (5.0 / 50.0 * 256.0); AFE4400Write(LEDCNTRL, (1L << 16) | (drive_led1 << 8) | (drive_led2)); // internal timer ON AFE4400Write(CONTROL1, (1L << 8) | (1L << 1));
The timings are set as in the datasheet.
What recommendations do you have to get this working? You mentioned on the forums that you tested the AFE4400 with the sensors I mentioned, do you mind telling which values you used with them?
Also, just because I've seen this in other forum posts: I am not using the EVM (the component really should not be operable only with an evaluation board and TI's signal conditioning code that isn't open source).
