M37270MF Datasheet, PDF (37/94 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER

MITSUBISHI MICROCOMPUTERS
M37270MF-XXXSP
M37270EF-XXXSP, M37270EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
(1) I²C Data Shift Register
The I²C data shift register (S0 : address 00F616) is an 8-bit shift
register to store receive data and write transmit data.
When transmit data is written into this register, it is transferred to the
outside from bit 7 in synchronization with the SCL clock, and each
time one-bit data is output, the data of this register are shifted one bit
to the left. When data is received, it is input to this register from bit 0
in synchronization with the SCL clock, and each time one-bit data is
input, the data of this register are shifted one bit to the left.
The I²C data shift register is in a write enable status only when the
ES0 bit of the I²C control register (address 00F916) is “1.” The bit
counter is reset by a write instruction to the I²C data shift register.
When both the ES0 bit and the MST bit of the I²C status register
(address 00F816) are “1,” the SCL is output by a write instruction to
the I²C data shift register. Reading data from the I²C data shift regis-
ter is always enabled regardless of the ES0 bit value.
Note: To write data into the I²C data shift register after setting the
MST bit to “0” (slave mode), keep an interval of 8 machine
cycles or more.
(2) I²C Address Register
The I²C address register (address 00F716) consists of a 7-bit slave
address and a read/write bit. In the addressing mode, the slave ad-
dress written in this register is compared with the address data to be
received immediately after the START condition are detected.
s Bit 0: Read/write bit (RBW)
Not used in the 7-bit addressing mode. In the 10-bit addressing mode,
the first address data to be received is compared with the contents
(SAD6 to SAD0 + RBW) of the I²C address register.
The RBW bit is cleared to “0” automatically when the stop condition
is detected.
s Bits 1 to 7: Slave address (SAD0–SAD6)
These bits store slave addresses. Regardless of the 7-bit address-
ing mode and the 10-bit addressing mode, the address data trans-
mitted from the master is compared with the contents of these bits.
7
0
SAD6 SAD5 SAD4 SAD3 SAD2 SAD1 SAD0 RBW
I² C address register
(S0D: address 00F716)
Read/write bit
Slave address
Fig. 37. Structure of I²C address register
(3) I²C Clock Control Register
The I²C clock control register (address 00FA16) is used to set ACK
control, SCL mode and SCL frequency.
s Bits 0 to 4: SCL frequency control bits (CCR0–CCR4)
These bits control the SCL frequency. Refer to Table 7.
s 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.
s Bit 6: ACK bit (ACK BIT)
This bit sets the SDA status when an ACK clock^V is generated. When
this bit is set to “0,” the ACK return mode is set and make SDA “L” 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 “H” status at the oc-
currence 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
made “L” (ACK is returned). If there is a mismatch between the slave
address and the address data, the SDA is automatically made
“H”(ACK is not returned).
VACK clock: Clock for acknowledgement
s 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 “H”) and receives the ACK bit generated
by the data receiving device.
Note: Do not write data into the I²C clock control register during
transmitting. If data is written during transmitting, the I²C clock
generator is reset, so that data cannot be transmitted nor-
mally.
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