AN969 Datasheet, PDF (2/10 Pages) STMicroelectronics – SCI COMMUNICATION BETWEEN ST7 AND PC

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
ST7
SCI Interface _TDO
RDI
DEVICE
RDI
TDO
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.
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