NEC PD78P214 Manuale Utente

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Chapter 10   Clock Synchronous Serial Interface

In SBI communication, the master device outputs an address on the serial bus and, usually, one target slave device
is selected out of two or more devices according to the address.

Once the target device has been determined, commands and data are transferred between the master device and
slave device to implement serial communication.

Figs. 10-27 to 10-30 show the timing charts for data communication.

The conditions governing the release of the busy state depend on whether transmission or reception is permitted.
They can be applied to high-speed transfer using the SBI macro service.  Table 10-3 lists the methods of releasing
the BUSY state.

Divice and condition

CTxE

0

0

1

1

CRxE

0

1

0

1

BSYE

←0, SIO read access

BSYE

←0, SIO write access

Conditions governing the release of BUSY

Note  Write FFH into the SIO if the next operation is reception.

If WUP is set to 1 in the busy state, the wake-up state is set as soon as the device enters the ready state.

In the wake-up state, an interrupt (INTCSI) is issued only when an address is received.  The acknowledge (ACK)
signal is not detected in this state.

Start transmission and reception in the same way as the busy state is released.  Even if start of transmission and
reception is specified, transmission and reception are not started while the slave device is outputting the BUSY
signal.  Transmission and reception are started when the busy state is released.