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CHAPTER 5 PORT FUNCTIONS
5.2.4 Port 3
Port 3 is an 8-bit output only port with output latch. P30 to P37 pins go into a high-impedance state when the ENn
of port mode control register (PMC) is set to 0 and the port mode register 3 (PM3) is set to 1.
Alternate functions include meter control PWM output.
RESET input sets port 3 to high-impedance state.
Figure 5-5 shows a block diagram of port 3.
Figure 5-5. P30 to P37 Block Diagram
PM : Port mode register
RD
: Port 3 read signal
WR : Port 3 write signal
Caution
When PM3 is set to 0, read operation is enabled. When PM3 is set to 1, read operation is disabled.
Remark
n = 3, 4
P30/SM31 to P33/SM34
P34/SM41 to P37/SM44
WR
PORT
WR
PM
Output latch
(P30 to P37)
PM30 to PM37
Alternate
functions
Internal bus
RD
Selector
Decoder
2
DIRn1 DIRn0
MODn ENn
Содержание mPD780973 Series
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