CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS

Serial clock selection bit (W)

The P01/SCK pin status depends on the CSIM1 setting as shown below.

CSIM1

P01/SCK Pin Status

0

High impedance

1

High level

The following procedure should be used to clear CSIE during a serial transfer.

Clear the interrupt enable flag (IECSI) to set the interrupt disabled state.

Clear CSIE.

Clear the interrupt request flag (IRQCSI).

5.5.53-Wire Serial I/O Mode Operation

The 3-wire serial I/O mode allows connection to the system used in the 75X series, μPD7500 series, 87AD series, etc.

Communication is performed using three lines: The serial clock (SCK), serial output (SO), and serial input (SI).

Fig. 5-28 Example of 3-Wire Serial I/O System Configuration

 

3-wire serial I/O 3-wire serial I/O

Master CPU

Slave CPU

SCK

SCK

SO

SI

SI

SO

(1) Register setting

When the device is used in the 3-wire serial I/O mode, setting can be performed by means of the following two registers:

Serial operating mode register (CSIM)

Serial bus interface control register (SBIC)

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NEC PD75402A, PD75P402 user manual 5 3-Wire Serial I/O Mode Operation, Example of 3-Wire Serial I/O System Configuration