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4-MULTIPLEXED LCD WITH A STANDARD ST62

Figure 7. Template for MCU – LCD connections

2.1.2 Driver subroutines and variables

The main application communicates with the LCD driver through six 8-bit variables and 3 sub-

routines, all declared in LCD_drv.inc.

The six variables are written by the main application and read by the software LCD driver.

They describe the information that should be displayed:

– hr_dig1, hr_dig0, min_dig1 and min_dig0 contain the code of the character to be dis-

played on each 7-segment digit;

– icons is a byte of flags indicating, for each icon, if it must be ON or OFF;

– flashing is a byte of flags indicating, for each 7-segment digit and each icon, if it must be

flashing or not.

commons

port

ST62

segments port

LCD

470k resistors

AM

PM

°C