Analog Devices EE-60 Simulating RS-232 UART Using ADSP-21xx Synchronous Serial Ports

About this manual

This document describes a method for using the synchronous serial ports on the ADSP-21xx family of digital signal processors to perform bi-directional RS-232 communications. It addresses the challenge that RS-232 ports lack a clock signal and framing signal, which are required by the DSP's serial ports. The note details how to configure the DSP to sample incoming data at a multiple of the bit rate to handle phase uncertainty and how to manually insert start and stop bits for transmission.

What's inside

• Introduction
• Overview of RS-232 Communications
• Overview of DSP Interface
• Data Reception
• Data Transmission
• Code Examples

Frequently asked questions

What is the purpose of this application note?

It presents a method to use synchronous serial ports on ADSP-21xx digital signal processors for bi-directional RS-232 communications.

What sampling rate is required if the RS-232 device transmits at 9600 BAUD?

The data must be sampled at 28,000 bits/second.

How many bits of data must be captured to receive one RS-232 word?

The system needs to capture 29 bits of data.