abstract.txt

keil-C51完全破解版-28.7M.zip

LPC932 EXAMPLE:	COMMUNICATION WITH THE PC USING THE SERIAL INTERFACE (UART)
Christian Kulig, 12/05/02

INTRODUCTION:
The LPC932 has an enhanced UART which is compatible with the conventional 80C51 
UART. It can be used directly as a serial interface to exchange data with other 
microcontrollers. To communicate with a PC it is necessary to use a levelshifter 
like the MAX563 or similar. To transfer data, the UART uses a certain baud rate 
(bits per second), which must be the same for the transmitter and the receiver. 
For PCs there are standard baud rates like 1200, 4800, 9600 and so on, which 
should be used for the UART of the microcontroller as well. On the LPC932 the 
source for the baud rate can be e.g. the Timer 1 overflow or the independent 
Baud Rate Generator (BRG). Both divide the clock frequency (Crystal, internal 
RC oscillator) by a certain factor, so that many different baud rates can be 
achieved.

DESCRIPTION:
This example shows how to use the UART to communicate with a PC:
It sets up the 8 data bits mode with 1 stop bit and no parity bit. The baud 
rate source is the internal Baud Rate Generator, which is set up to provide 
a baud rate of 9600 at an oscillator frequency of 12 MHz (=external resonator).
To have access to the com port of the PC, start the program 'Hyperterminal'.
(START -> PROGRAMS -> ACCESSOIRES -> COMMUNICATIONS -> HYPERTERMINAL)
Click on 'Properties' and check the following settings: 9600 baud, 8 data 
bits, 1 stop bit and no flow control. To begin the communication click on 'Call'.
The LPC932 waits for a command ('S'), which is sent by 'Hyperterminal' and sends
back a response which is displayed on the screen.