HD404639R Datasheet, PDF (82/135 Pages) Renesas Technology Corp – 4-Bit Single-Chip Microcomputer

HD404639R Series
Serial Communications Interface
The MCU has two channels of serial interface. The transfer and receive start instructions differ according to
the serial interface channel, but other functions are the same. The serial interface serially transfers or
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 multiplexer are also configured for serial interfaces 1 and 2 as
follows.
Serial interface 1
• Serial data register 1 (SR1L: $006, SR1U: $007)
• Serial mode register 1A (SM1A: $005)
• Serial mode register 1B (SM1B: $028)
• Port mode register A (PMRA: $004)
• Miscellaneous register (MIS: $00C)
• Octal counter (OC1)
• Selector
Serial interface 2
• Serial data register 2 (SR2L: $01D, SR2U: $01E)
• Serial mode register 2A (SM2A: $01B)
• Serial mode register 2B (SM2B: $01C)
• Port mode register A (PMRA: $004)
• Octal counter (OC2)
• Selector
The block diagram of the serial interface is shown in figure 66.
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