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CHAPTER 2
PIN FUNCTIONS
User’s Manual U12790EJ2V0UD
(c) SB0 and SB1
These are NEC standard serial bus interface I/O pins.
SB0 and SB1 are N-ch open drain.
(d) BUSY
This is the serial interface automatic transmit/receive busy input pin.
(e) STB
This is the serial interface automatic transmit/receive strobe output pin.
Caution
When this port is used for the serial interface, the I/O and output latches must be set
according to the required function. For the setting, refer to Table 4-3 Port Mode Register
and Output Latch Settings When Using Alternate Functions and Figure 13-5 Format of
Serial Operating Mode Register 0 (CSIM0).
2.2.4 P30 to P37 (Port 3)
These are 8-bit I/O port pins. Beside serving as I/O port pins, they also have VDD = 4.5 V monitor output, timer
output, timer input and buzzer output functions.
The following operating modes can be specified in 1-bit units.
(1) Port mode
These pins function as an 8-bit I/O port that can be set to input or output mode in 1-bit units using port mode
register 3.
(2) Control mode
These pins function as VDD = 4.5 V monitor output, timer output, timer input, and buzzer (BEEP0, BUZ) output
pins.
(a) VM45
This is the monitor output pin of VDD = 4.5 V.
(b) TO0
This is the output pin of the 16-bit timer/event counter.
(c) TI00
This is the external count clock input pin of the 16-bit timer/event counter and a capture trigger signal input
pin.
(d) TI01
This is a capture trigger signal input pin of the 16-bit timer/event counter.
(e) TI50, TI51
These are pins for external clock input to the 8-bit timer/event counter.
(f)
BEEP0, BUZ
These are buzzer output pins.
2.2.5 P40 to P47 (Port 4)
These are 8-bit I/O port pins.
They can be set to input or output mode in 8-bit units mode using port mode register 4.