MuMaker-PFM-M487KM
APR 30
, 2020
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Rev 1.00
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Heartbeat Sensor
2.7
NuMaker-PFM-M487KM features an on-board heartbeat sensor, it can detect the tiny electrical signal
between human
’s right and left hand during each heartbeat. The tiny electrical signal passes through
three stages of operational amplifiers which are built in M487KMCAN to amplify the differential
electrical signal and filter the noise of environment. The Figure 2-6 shows the heartbeat sensor block
diagram.
Heartbeat R/L Sensor Pads
The heartbeat sensor pads are used to detect the tiny electrical signal between human
’s right
and left hand during each heartbeat.
OPA0 (Differential Amplifier and Filter)
OPA0 is used to amplify the differential electrical signal between right and left sensor pads and
filter the DC bias then passes it to OPA1.
OPA1 (Bypass Filter and Input Buffer)
OPA1 is a bypass filter which is used to suppress 60Hz noise and pass the signal without the
noise to OPA2.
OPA2 (Amplifier)
OPA2 is used to amplify the signal comes from OPA1 then passes it to the ADC channel of
M487KMCAN to convert the analog signal to the digital signal.
Figure 2-6 Heartbeat Sensor Block Diagram