AN969 is an application note about the standard communication interface between a ST7 microcontroller and a PC. It includes the features of SCI communication and baud rate configuration.
This document presents a standard communications interface between an ST7 microcontroller and a PC. The communication is achieved through the ST7 SCI peripheral and a PC serial port using the RS232 protocol. It details the necessary hardware setup, including the use of a MAX232 chip for level conversion between TTL and RS232 signals.
The guide provides specific configuration instructions for the ST72F264 microcontroller, including baud rate selection, word length settings, and enabling transmission and reception modes. It also includes a software example using the Windows 98 HyperTerminal application to demonstrate the polling strategy for data exchange.
| Microcontroller Model | ST72F264 |
|---|---|
| External Clock Frequency | 16 MHz |
| Internal Clock Frequency | 8 MHz |
| Communication Protocol | RS232 |
| Data Word Length | 8 or 9 bits |
| Example Baud Rate | 9600 bps |
A MAX232 is used for the purpose of converting between the PC and the SCI peripheral.
The HyperTerminal application is used to configure the PC as a terminal.
The baud rate is calculated using the formula TX = fopy/(16*PR*TR) and RX = fopy/(16*PR*RR).