I2C scan writes 0 bytes

[andrei-edward-popa]

Describe the bug
I'm wondering why the I2C scan example writes 0 bytes of data to test if a slave acknowledge the address. In some cases it happens that we can't scan the bus without sending a byte to see if a slave acknowledge the transfer. This happens for Designware I2C IP for example.

[henrikbrixandersen]

The reason for writing 0 bytes and checking for an ACK is that even writing one byte could be a destructive action (think for instance an I2C EEPROM, where writing one byte would change the change the contents of the EEPROM).

[andrei-edward-popa]

Yes, you are right, but what about to read 1 byte instead of a write?

[henrikbrixandersen]

Some SMBus chips are write-only and will thus not acknowledge a read request.

[andrei-edward-popa]

Okay, I understand, thanks for the explanation