UPD784020 Datasheet, PDF (41/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

mPD784020, 784021
(1) Three-wire serial I/O mode
This mode is designed for communication with a device incorporating a conventional synchronous serial interface.
Basically, three lines are used for communication: the serial clock line (SCK0) and serial data lines (SI0 and SO0).
In general, a handshake line is required to check the state of communication.
(2) SBI mode
The SBI mode allows communication with more than one device via two lines: the serial clock (SCK0) and serial
bus (SB0). The SBI mode is the standard NEC serial interface.
A master device outputs an address through the SB0 pin to select a slave device with which communication is
to be performed. After a target device is selected, commands and data are transmitted between the master device
and slave device.
8.9 EDGE DETECTION FUNCTION
The interrupt input pins (NMI, INTP0-INTP5) are used to apply not only interrupt requests but also trigger signals
for the built-in circuits. As these pins are triggered by an edge (rising or falling) of an input signal, a function for edge
detection is incorporated. Moreover, a noise suppression function is provided to prevent erroneous edge detection
caused by noise.
Pin
NMI
INTP0-INTP3
INTP4, INTP5
Detectable edge
Noise suppression method
Rising edge or falling edge
Analog delay
Rising edge or falling edge, or both edges Clock sampling^Note
Analog delay
Note INTP0 is used for sampling clock selection.
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