Port P3 (P37 To P30) (Large Current Port) - Philips CEM2100/00 Service Manual

5.4 Port P3 (P37 to P30) (Large Current Port)

Port P3 is an 8-bit input/output port.
When used as an input port, the corresponding output latch (P3DR) should be set to "1".
During reset, the P3DR is initialized to "1".
P3 port output latch (P3DR) and P3 port terminal input (P3PRD) are located on their respective address.
When read the output latch data, the P3DR should be read. When read the terminal input data, the P3PRD register
should be read.
Data input (P3PRD)
Output latch read (P3DR)
Data output (P3DR)
Note: i = 7 to 0
7 6
P3DR
(0003H)
P37 P36
R/W
P3PRD P37 P36
(000DH)
Read only
STOP
OUTEN
D Q
Figure 5-5 Port 3
5 4 3
P35 P34 P33
P35 P34 P33
Page 55
2 1 0
P32 P31 P30 (Initial value: 1111 1111)
P32 P31 P30
T5CL8
P3i