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EMBEDDED MULTITASKING

The Easy Way
by Charles Kosina

Start ý An Example ý State Machine Control ý Keyboard Scanning ý Receive Serial Data ý LCD Module ý Transmit Data ý Debugging Techniques ý Other Options ý Sources and PDF

RECEIVE SERIAL DATA

Some tasks cannot afford the luxury of waiting around for servicing. The serial port of the 8051 chip is one such example. To avoid losing incoming characters, the entire task is within an ISR.

When a character is received, it is stored in a circular buffer in RAM. A carriage return terminator sets a flag for Task 3, which then transfers the buffer to the LCD module. Listing 5 shows a compact and relatively simple routine to do this.

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