UPD784907 Datasheet, PDF (48/98 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLER

µPD784907, 784908
• 3-wire serial I/O mode
This mode is designed for communication with a device incorporating a conventional clocked serial interface.
Basically, three lines are used for communication: the serial clock line (SCKn) and serial data lines (SIn and SOn)
(n = 0, 3).
In general, a handshake line is required to check the state of communication.
8.9 Clock Output Function
The frequency of the CPU clock signal can be divided and output from the system. Moreover, the port can be used
as a 1-bit port.
The ASTB pin is also used as the CLKOUT pin, so that when this function is used, the local bus interface cannot
be used.
Figure 8-14. Block Diagram of Clock Output Function
fCLK
fCLK/2
fCLK/4
fCLK/8
fCLK/16
Output control
CLKOUT
Enable output Output level
48
Data Sheet U11680EJ2V0DS00