M37160M8 Datasheet, PDF (33/131 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

M37160M8/MA/MF-XXXSP/FP,M37160EFSP/FP
8.6.3 I²C Clock Control Register
The I²C clock control register (address 00FA16) is used to set ACK
control, SCL mode and SCL frequency.
(1) Bits 0 to 4: SCL frequency control bits (CCR0–CCR4)
These bits control the SCL frequency.
(2) Bit 5: SCL mode specification bit (FAST MODE)
This bit specifies the SCL mode. When this bit is set to “0,” the stan-
dard clock mode is set. When the bit is set to “1,” the high-speed
clock mode is set.
(3) Bit 6: ACK bit (ACK BIT)
This bit sets the SDA status when an ACK clock^✽ is generated. When
this bit is set to “0,” the ACK return mode is set and SDA goes to
LOW at the occurrence of an ACK clock. When the bit is set to “1,”
the ACK non-return mode is set. The SDA is held in the HIGH status
at the occurrence of an ACK clock.
However, when the slave address matches the address data in the
reception of address data at ACK BIT = “0,” the SDA is automatically
goes to LOW (ACK is returned). If there is a mismatch between the
slave address and the address data, the SDA is automatically goes
to HIGH (ACK is not returned).
✽ACK clock: Clock for acknowledgement
(4) Bit 7: ACK clock bit (ACK)
This bit specifies a mode of acknowledgment which is an acknowl-
edgment response of data transmission. When this bit is set to “0,”
the no ACK clock mode is set. In this case, no ACK clock occurs
after data transmission. When the bit is set to “1,” the ACK clock
mode is set and the master generates an ACK clock upon comple-
tion of each 1-byte data transmission.The device for transmitting
address data and control data releases the SDA at the occurrence of
an ACK clock (make SDA HIGH) and receives the ACK bit generated
by the data receiving device.
Note: Do not write data into the I²C clock control register during transmission.
If data is written during transmission, the I²C clock generator is reset, so
that data cannot be transmitted normally.
I²C Clock Control Register
b7 b6 b5 b4 b3 b2 b1 b0
I²C clock control register (S2) [Address 00FA16]
B
Name
Functions
After reset R W
0 SCL frequency control Setup value Standard High speed
to bits
of CCR4–
clock
clock mode
4 (CCR0 to CCR4)
CCR0
mode
00 to 02 Setup disabled Setup disabled
0 _RW
03
Setup disabled
333
04
Setup disabled
250
05
100
400 (See note)
06
83.3
166
5 SCL mode
specification bit
(FAST MODE)
500/CCR value 1000/CCR value
1D
17.2
34.5
1E
16.6
33.3
1F
16.1
32.3
(φ = at 4 MHz, unit : kHz)
0: Standard clock mode
1: High-speed clock mode
0 _RW
6 ACK bit
(ACK BIT)
0: ACK is returned.
1: ACK is not returned.
0 _RW
7 ACK clock bit
(ACK)
0: No ACK clock
1: ACK clock
0 RW
Notes 1. At 400kHz in the high-speed clock mode, the duty is as below .
“0” period : “1” period = 3 : 2
In the other cases, the duty is as below.
“0” period : “1” period = 1 : 1
2.At FSCIN = 4.43 MHz, φ = 8.86/2 MHz
Values shown in table is as below :
At FSCIN = 4.43 MHz, each value ✕ 8.86/8
Fig. 8.6.4 I²C Clock Control Register
Rev.1.01 2003.11.13 page 33 of 130