R01UH0822EJ0100 Rev.1.00
Page 614 of 1041
Jul 31, 2019
RX13T Group
23. Serial Communications Interface (SCIg, SCIh)
23.2.12
Modulation Duty Register (MDDR)
The MDDR register corrects the bit rate adjusted by the BRR register.
When the SEMR.BRME bit is set to 1, the bit rate generated by the on-chip baud rate generator is evenly corrected
according to the settings of the MDDR register (M/256). The relationship between the MDDR register setting (M) and
the bit rate (B) is given in
.
The range of the value that can be set in the MDDR register is from 80h to FFh. A value other than these cannot be set.
The MDDR register is writable only when the TE and RE bits in the SCR register are 0.
B:
Bit rate (bps)
M:
MDDR setting (128 ≤ MDDR ≤ 256)
N:
BRR setting for baud rate generator (0 ≤ N ≤ 255)
PCLK:
Operating frequency (MHz)
n and S:
Determined by the settings of the SMR and SCMR registers as listed in Table 23.12 and Table 23.13, section
23.2.11, Bit Rate Register (BRR).
Note 1. Do not use this function in clock synchronous mode and in the highest speed settings in simple SPI mode (SMR.CKS[1:0] =
00b, SCR.CKE[1] = 0, and BRR = 0).
Note 2. Adjust the bit rate so that the widths at high and low level of the SCL output in simple I
2
C mode satisfy the I
2
C-bus standard.
Address(es): SCI1.MDDR 0008 A032h, SCI5.MDDR 0008 A0B2h, SCI12.MDDR 0008 B312h
b7
b6
b5
b4
b3
b2
b1
b0
Value after reset:
1
1
1
1
1
1
1
1
Table 23.24
Relationship between MDDR Setting (M) and Bit Rate (B) When Bit Rate Modulation Function is
Used
Mode
SEMR Settings
BRR Setting
Error (%)
BGDM Bit ABCS Bit
Asynchronous,
multi-processor
communication
0
0
1
0
0
1
1
1
Clock synchronous, simple SPI*
Smart card interface
Simple I
2
N
PCLK 10
6
64 2
2n 1
–
256
M
----------
B
-------------------------------------------------------
1
–
=
Error
PCLK 10
6
B 64
2
2n 1
–
256
M
----------
N 1
+
--------------------------------------------------------------------------------
1
–
100
=
N
PCLK 10
6
32 2
2n 1
–
256
M
----------
B
-------------------------------------------------------
1
–
=
Error
PCLK 10
6
B 32
2
2n 1
–
256
M
----------
N 1
+
--------------------------------------------------------------------------------
1
–
100
=
N
PCLK 10
6
16 2
2n 1
–
256
M
----------
B
-------------------------------------------------------
1
–
=
Error
PCLK 10
6
B 16
2
2n 1
–
256
M
----------
N 1
+
--------------------------------------------------------------------------------
1
–
100
=
N
PCLK 10
6
8 2
2n 1
–
256
M
----------
B
----------------------------------------------------
1
–
=
N
PCLK 10
6
S 2
2n 1
+
256
M
----------
B
-----------------------------------------------------
1
–
=
Error
PCLK 10
6
B S
2
2n 1
+
256
M
----------
N 1
+
------------------------------------------------------------------------------
1
–
100
=
N
PCLK 10
6
64 2
2n 1
–
256
M
----------
B
-------------------------------------------------------
1
–
=