Bus scanner

i2cdetect finds devices by knocking on every address: a device that is there acknowledges, an empty address raises OSError (errno 121).

Build: two chips on the I²C pins, both on 3V3:

• an MPU-6050 with AD0 to GND (0x68),
• a BME280 with SDO to 3V3, which moves it to 0x77.

Program: try read_byte(address) for every address from 0x03 to 0x77, catching OSError. Print each address that answers, in order, then the total:

Found 0x68
Found 0x77
2 devices