R01UH0092EJ0110 Rev.1.10
Page 549 of 807
Jul 31, 2012
M16C/64C Group
25. Multi-master I
2
C-bus Interface
PED (SDAMM/port function switch bit) (b2)
PEC (SCLMM/port function switch bit) (b3)
Bits PEC and PED are enabled when the ES0 bit in the S1D0 register is 1 (I
2
C interface enabled).
When the PEC bit is set to 1 (output port), the P7_1 bit value is output from the SCLMM pin regardless
of the internal SCL output signal and PD7_1 bit value. When the PED bit is set to 1 (output port), the
P7_0 bit value is output from the SDAMM pin regardless of the internal SDA output signal and PD7_0
bit value.
The signal level on the bus is input to the internal SDA and internal SCL.
When bits P7_1 to P7_0 in the P7 register are read after setting bits PD7_1 and PD7_0 in the PD7
register to 0 (input mode), the level on the bus can be read regardless of the values set to bits PED and
PEC. Table 25.7 lists SCLMM and SDAMM Pin Functions.
SDAM (Internal SDA output monitor bit) (b4)
SCLM (Internal SCL output monitor bit) (b5)
The internal SDA and SCL output signal levels are the same as the output level of the I
2
C interface
before it has any effect from the external device output. Bits SDAM and SCLM are read only bits. If
necessary, set these bits to 0.
ICK1 and ICK0 (I
2
C-bus system clock select bit) (b7-b6)
Rewrite these bits when the ES0 bit in the S1D0 register is 0 (I
2
C interface disabled). fVIIC is selected
by setting all the bits ICK1 to ICK0, bits ICK4 to ICK2 in the S4D0 register, and the PCLK0 bit in the
PCLKR register. Refer to 25.3.1.2 “Bit Rate and Duty Cycle”.
Table 25.7
SCLMM and SDAMM Pin Functions
Pin
S1D0 Register
S3D0 Register
Pin Function
ES0 bit
PED bit
PEC bit
P7_1/SCLMM
0
-
-
I/O port or other peripheral pins
1
-
0
SCLMM (SCL input/output)
-
1
Output port (output P7_1 bit value)
P7_0/SDAMM
0
-
-
I/O port or other peripheral pins
1
0
-
SDAMM (SDA input/output)
1
-
Output port (output P7_0 bit value)
–: 0 or 1
Table 25.8
I
2
C-bus System Clock Select Bits
S4D0 Register
S3D0 Register
fVIIC
ICK4 Bit
ICK3 Bit
ICK2 Bit
ICK1 Bit
ICK0 Bit
0
0
0
0
0
fIIC divided-by-2
0
0
0
0
1
fIIC divided-by-4
0
0
0
1
0
fIIC divided-by-8
0
0
1
–
–
fIIC divided-by-2.5
0
1
0
–
–
fIIC divided-by-3
0
1
1
–
–
fIIC divided-by-5
1
0
0
–
–
fIIC divided-by-6
–: 0 or 1
Only set the values listed above.
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