3.2.6.6.1 TWI Bus Distribution

The SAMA7G54-EK features three dedicated TWIs to access the on-board devices.

The TWI interface uses only two lines, namely serial data (TWD) and serial clock (TWCK). According to the standard, the TWI clock rate is limited to 400 kHz in Fast mode and 100 kHz in Normal mode, but a configurable baud rate generator enables adapting the output data rate to a wide range of core clock frequencies. The TWI supports both Host and Client modes.

The first interface is used to access the following devices:

  • MCP16502 power management unit (address: 1011_011[R/W])
  • PAC1934 voltage monitor (address: 0010_000[R/W])
Figure 3-20. First TWI Interface

The second interface is used to access the following devices:

  • ATECC608A secure element (address: 1100_000[R/W])
  • Any camera module placed on the RPi CSI MIPI connector
  • First 24AA025E48 serial EEPROM (address: 1010_010[R/W])
  • Second 24AA025E48 serial EEPROM (address: 1010_011[R/W])
Figure 3-21. Second TWI Interface

The third interface is used to access any device placed on one of the following:

  • mikroBUS 1 connector
  • mikroBUS 2 connector
  • RPi 40-pin connector
Figure 3-22. Third TWI Interface