The F2800x devices contain varying numbers of the following communication peripherals:

• Controller Area Network (CAN/DCAN)
• Modular Controller Area Network (MCAN/CAN FD)
• Inter-Integrated Circuit (I2C)
• Power Management Bus (PMBus) Interface
• Serial Communication Interface (SCI)
• Serial Peripheral Interface (SPI)
• Local Interconnect Network (LIN)
• Fast Serial Interface (FSI)
• Host Interface Controller (HIC)

Because of the nature of these peripherals and the different means through which they communicate, each system must be designed with the intended comm peripheral support in mind. Board-level interfaces, which include I2C, PMBus, and SPI, are connected to other devices, either on the board or through the system. Because these drivers are normally run directly, be sure to pay close attention to the drive capability and trace length. These factors depend on the selected frequency of these signals.

When making use of CAN, it is recommended to implement an external oscillator on the board as opposed to using the internal oscillator. Depending on the required CAN parameters like bit time settings, bit rate, bus length, and propagation delay, the accuracy of the on-chip zero-pin oscillator may not meet the requirements of the CAN protocol. More information about this can be found in Section 3.6.1 as well as the Programming Examples and Debug Strategies for the DCAN Module.

Notably for I2C, it is recommended that the SDAA and SCLA pins are pulled high using external pull-up resistors. Too strong of a pull-up (smaller resistor value) prevents the I2C pins from effectively being driven low, whereas too weak of a pull-up (larger resistor value) can impact the communication speeds. This value should be selected based on a compromise between power consumption and speed. To calculate the idea pull-up resistor range, refer to application report I2C Bus Pullup Resistor Calculation.

Interfaces that can connect two or more boards running under different processors include SCI, CAN, LIN, and FSI. These ports often require specialized transceiver parts that transform the electrical signal to combat noise and enable communication with the ports on other devices. When using a communication transceiver, some transceivers may require pull-up resistors on the communication pins of the MCU. Verify this requirement with the transceiver's data sheet.

The SCI communication peripheral is a 2-wire asynchronous serial port with two external pins, SCITXD (SCI transmit-output) and SCIRXD (SCI receive-input). This protocol is commonly referred to as UART, and the protocol on the C2000 devices use the standard NRZ format. For some transceiver implementations, it is recommended to have a pull-up resistor on the SCI-RX pin to allow for the signal to return to high logic level without being driven. This prevents that GPIO pin from floating between values which would lead to errors and increased current consumption. Verify this pull-up resistor requirement with the data sheet of the specific transceiver being used. The pull-up resistor is especially necessary when using some types of transceivers to ensure deterministic operation of the SCI module. This resistor value should be selectively chosen and tested within the system, as the ideal value is highly dependent on the particular application. Too weak of a pull-up value (larger resistance) would prevent the resistor from actually pulling up a tri-stated or floating output from another device. Likewise, too strong of a pull-up value (smaller resistance) would prevent the output signal from toggling from the other device. A good starting point for experimenting this value would be 10 kΩ. For more information about debugging and troubleshooting SCI transmissions, see the SCI FAQ Thread on E2E.

For additional reference material for various communication peripheral protocols, see the following documentation:

• TMDSFSIADAPEVM FSI Adapter Board User’s Guide
• Fast Serial Interface (FSI) Skew Compensation