Hello,
the RCWL-9600 is very accurate.
You may read the data using a simple function like this:
#define M5_I2C_ADDR_ULTRA 0x57
float ReadI2CDistance()
{
uint32_t data;
Wire.beginTransmission(M5_I2C_ADDR_ULTRA);
Wire.write(0x01);
Wire.endTransmission();
delay(120);
Wire.requestFrom(M5_I2C_ADDR_ULTRA,3);
data = Wire.read();data <<= 8;
data |= Wire.read();data <<= 8;
data |= Wire.read();
return float(data) / 10000; // distance in cm
}
My M5Stack Core kept the small battery in good conditions for months (not using it) until I started to connect an ultrasonic unit to the groove port.
Basically I discovered that the 5V on the grove connector are DIRECTLY connected to the battery, and even if the Core is in deep sleep/off, there is still voltage on the pin that powers the ultrasonic unit. As result, leaving the Core turned off, but with the unit cable still connected to the grove port for weeks, slowly HARD drain the battery, until the battery is destroyed and then is not possible to recharge it any more.