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94
μ
PD75518(A)
(4) Slave address register (SVA)
The slave address register (SVA) has the two functions described below.
SVA is manipulated using an 8-bit manipulation instruction. SVA allows only write operation.
When the RESET signal is entered, the value of SVA is undefined. However, the value of SVA is preserved
when the RESET signal is entered in the standby mode.
Slave address detection
[In the SBI mode]
SVA is used when the
μ
PD75518(A) is connected as a slave device to the serial bus. SVA is an 8-bit
register for a slave to set its slave address (number assigned to it). The master outputs a slave address
to the connected slaves to select a particular slave. Two data values (a slave address output from the
master and the value of SVA) are compared with each other by the address comparator. If a match
is found, the slave is selected.
At this time, bit 6 (COI) of serial operation mode register 0 (CSIM0) is set to 1.
Cautions 1. Slave selection or nonselection state is detected by detecting a match for a slave address
received after bus release (in the state of RELD = 1).
For this match detection, an address match interrupt (IRQCSI0) generated when WUP is set
to 1 is usually used. So detect selection/nonselection state by slave address when WUP
is set to 1.
2. When detecting selection/nonselection state without using an interrupt when WUP is 0,
do not use the address match detection method. Instead, use transfer of commands set
in advance in a program.
Error detection
[In the two-wire serial I/O mode or SBI mode]
SVA detects an error in either of the following cases:
When addresses, commands, or data is transferred with the
μ
PD75518(A) operating as the master
When data is transferred with the
μ
PD75518(A) operating as a slave
4.8.4 Signals
Table 4-10 lists signals. Fig. 4-38 to 4-43 show operations of signals and flags.