
HD404358 Series
60
Port Mode Register A (PMRA: $004):
Four-bit write-only register that selects D
3
/BUZZ pin function as
shown in figure 44. It is reset to $0 by MCU reset.
Serial Interface
The serial interface serially transfers and receives 8-bit data, and includes the following features.
Multiple transmit clock sources
External clock
Internal prescaler output clock
System clock
Output level control in idle states
Five registers, an octal counter, and a selector are also configured for the serial interface as follows.
Serial data register (SRL: $006, SRU: $007)
Serial mode register (SMR: $005)
Port mode register A (PMRA: $004)
Port mode register C (PMRC: $025)
Miscellaneous register (MIS: $00C)
Octal counter (OC)
Selector
The block diagram of the serial interface is shown in figure 51.