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SCI COMMUNICATION BETWEEN ST7 AND PC

1 SCI COMMUNICATION

The main features of the SCI communication peripheral are summarized below. Refer to your

ST7 datasheet for more details.

1.1 MAIN FEATURES

The Serial Communication Interface (SCI) offers a flexible means of full-duplex data exchange

with external equipment requiring an industry standard NRZ asynchronous serial data format.

The SCI allows a very wide range of baud rates with different baud rates for transmission and

reception.

For SCI communication, only two signals are needed, one for transmission and the other for

reception. No clock signal is needed as it works in asynchronous mode. Each device has a

Transmit Data Output pin (TDO pin) and a Receive Data Input pin (RDI pin). See Figure 1.

Figure 1. ST7 and SCI interface set-up

The user must be very careful in identifying the use of each pin. This can easily be done

putting the device in transmission and checking with an oscilloscope if a transmission frame is

present or not.

1.2 BAUD RATES

Transmission and reception can be driven by their own baud rate generator. However be

aware that to communicate correctly, the receiver must have a reception baud rate strictly

equal to the transmission baud rate of the transmitter. If not, the communication will be cor-

rupted. As long as this condition is met, a wide range of baud rates is possible.

ST7

SCI Interface

DEVICE

TDO

RDI

RDI

TDO

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