8 I²C Interface

The I²C interface uses the SDA and SCL pins to indicate various I/O states to the ECC608-TMNGTLS. This interface is designed to be compatible with other Microchip CryptoAuthentication and Serial EEPROM devices at the protocol level. Exact commands and device I²C Addresses may differ.

The SDA pin is normally pulled high with an external pull-up resistor because the ECC608-TMNGTLS client includes only an open-drain driver on its output pin. The bus host may either be open-drain or totem pole. In the latter case, it must be tri-stated when the ECC608-TMNGTLS is driving results on the bus. The SCL pin is an input and must be driven both high and low at all times by an external device or resistor.

For the ECC608-TMNGTLS, the default 7-bit I²C address is defined to be 0x38. With this value, the I²C address write/read byte values will be 0x70 and 0x71, respectively. If so desired, the I²C address value can be overwritten one time using the UpdateExtra command.

Remember: The I²C standard uses the terminology “Master” and “Slave”. The equivalent Microchip terminology used in this document is “Host” and “Client”, respectively.

8 I2C Interface

8 I²C Interface