SN8P1800 Datasheet, PDF (107/129 Pages) SONiX Technology Company – 8-Bit Micro-Controller

SN8P1800
8-bit micro-controller build-in 12-bit ADC + 72 dots LCD driver
THE PORT3 DISCRIPTION
The port 3 is input only pins and shared with SEG8~SEG15 LCD driver pins. The port3 can work with LCD working. To
set the bit1 of OPTION register (P3LCD) be “1”, the port 3 input function will be enabled. The port3 input is with pull-up
resistors.
Port3 structure
PUR
Pin
OPTION Register
OPTION initial value = xxxx xx00
088H
Bit 7
Bit 6
OPTION
-
-
-
-
Int. bus
P3LCD
LCD waveform
Figure 11-4. Port 3 Block Diagram
Bit 5
Bit 4
Bit 3
Bit 2
-
-
-
-
-
-
-
-
P3LCD: P3 input function control bit. 0 = LCD driver pin, 1 = input port.
Bit 1
P3LCD
R/W
Bit 0
RLCK
R/W
Example: Enable PORT 3 output function.
Step1: Enable the P3 general input function by P3LCD control bit (“1”).
B0BSET
FP3LCD
; Enable P3 general input function.
Step2: Now the PORT 3 general input function is enable. User can read data by PORT 3.
B0MOV
A, P3
; Read P3 value.
NOTE: The PORT 3 register (P3) is read-only register and doesn’t support bit set/clear instruction.
B0BSET
B0BCLR
P3.0
P3.0
; ERROR!! Bit set instruction.
; ERROR!! Bit clear instruction.
SONiX TECHNOLOGY CO., LTD
Page 107
Revision 1.94