Serial Communication in C

Abstract

This chapter looks at the serial communication capability of the MSP430 [1, 2, 3, 4]. Serial communication uses a single wire to send information between a transmitter (Tx) and a receiver (Rx) as a sequence of bits. This is the opposite of how we can send information as a full word using the MCU ports, which is considered parallel communication. Serial communication allows information to be transmitted using less pins compared to parallel communication, but at a slower overall information transmission rate due to only sending one bit at a time as opposed to a full word. The MSP430 contains dedicated peripherals to handle serial communication called the enhanced Universal Serial Communication Interfaces (eUSCI). The MSP430FR2355 contains four separate eUSCI peripherals called eUSCI_A0, eUSCI_A1, eUSCI_B0, and eUSCI_B1. The MSP430FR2355 supports three serial communication modes including: (1) universal asynchronous receiver/transmitter (UART); (2) serial peripheral interface (SPI); and (3) inter-integrated circuit (I2C) protocol. The eUSCI_A0 and eUSCI_A1 peripherals can be configured to support either UART or SPI. The eUSCI_B0 and eUSCI_B1 peripherals can be configured to support either SPI or I2C. This chapter gives an overview of the UART, SPI, and I2C protocols and presents how to use these communication modes on the eUSCIs within the MSP430FR2355 in C.