Hi,
Yes, You can read the raw data without the support of STM32 I2C interface , Grove - Finger-clip Heart Rate Sensor is based on PAH8001EI-2G , we can use the PAH8001EI-2G I2C interface to read the raw data in order to that you need to make some alteration in the module ,
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You can see that from provided schematic , the SCL is PAH8001EI-2G pin 15 and the SDA is PAH8001EI-2G pin 9 .
You can use a jumber wire and make conection to your master baord and read the data , for more deatils about the raw data aquasistion you can read the PAH8001EI-2G Datasheet.
