Functional Description
CPB902
C P B 9 0 2 U s e r M a n u a l
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4.3.13
LCD and Matrix Keyboard Port
LCD monitors and matrix keypads share J17 header on the top side of CPB902 processor module.
4.3.13.1
LCD Connection
The CPB902 connector J17 is used for connection of LCD monitors based on HD44780, S6A0069,
S6B0108 or compatible controllers. Sample LCD connection diagrams are shown in the figures
below (4.23, 4.24). The driver power voltage is controlled by R154 adjustable potentiometer and
J18 pinpad jumper (see description and a diagram below in this section).
Two ports in I/O address space are dedicated for data transmission and control purposes when
working with LCDs. They are Command/Data port (319h) and Control port (31Ah).
Commands/Data port:
Port address –
319h
The port is available for read/write
Assignment: read/write data to/from LCD, write commands to LCD, read LCD status.
Control Port:
Port Address:
31
А
h
The control bits of this port are used to set the required timing chart for data exchange between the
processor and LCD.
Control Port Bits Designation:
Bit
Read/Write
Function
0
Read
Always 1. LCD available for read.
1
Read
Always 0
2
Read
Always 0
3
Read/Write
/LCD_CS2 line control
4
Read/Write
LCD_E line control
5
Read/Write
LCD_RS line control
6
Read/Write
LCD_R/W line control
7
Read/Write
/LCD_CS1 line control
