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16.7 Notes on Using the Multi-address I
2
C
16.7 Notes on Using the Multi-address I
2
C
This section describes precautions to take when using the multi-address I
2
C interface.
I
Precaution in Setting the Multi-address I
2
C Interface Register
Before writing to the bus control register (MBCR), the multi-address I
2
C interface must be
enabled (MCCR: EN).
When the master slave selection bit (MBCR: MSS) is set, transfer starts.
I
Precaution in Setting Shift Clock Frequency
To calculate the shift clock frequency using the F
sck
expression (1) in Table 16.4-3 "Function of
Each Bit in Multi-address I
2
C Clock Control Register (MCCR)", it is necessary to know the
values of m, n, and DMBP.
When the value of m is 5 (MCCR: CS4 = CS3 =0) and the value of n is 4 (MCCR: CS2 = CS1 =
CS0 = 0), "DMBP = 1" cannot be selected. Other combinations do not present a problem.
I
Precaution on the Priority at Simultaneous Writing
Contention of the next byte transfer and stop condition
When "0" is written to MBCR: MSS in states where MBCR: INT is cleared, the MSS bit has a
higher priority and a stop condition is generated.
Contention of the next byte transfer and start condition
When "1" is written to MBCR: SCC in states where MBCR: INT is cleared, the SCC bit has a
higher priority and a start condition is generated.
I
Precaution on Setting with Software
Do not select the repeated start condition (MBCR: EN = 0) and the slave mode (MBCR: MSS =
0) at the same time.
In states where the interrupt request flag bits (BER and INT in the MBCR register) are set to "1"
and the interrupt request enable bits are enabled (BEIE and INTE in the MBCR register are set
to "1"), recovery from the interrupt processing cannot be performed. Clear the BER and INT bits
in the MBCR register.
When the multi-address I
2
C operation is not permitted (MCCR: EN = 0), all bits of the bus status
register MBSR and the bus control register MBCR (excluding the bus error BER bit and the bus
error enable BEIE bit) are cleared.