M37151 datasheet(42/139 Pages) RENESAS

42 / 139 page

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER

and ON-SCREEN DISPLAY CONTROLLER

MITSUBISHI MICROCOMPUTERS

M37151M6/M8/MA/MC/MF-XXXFP, M37151EFFP

Rev. 1.0

(3) RESTART condition generation procedure

➀ Procedure example (The necessary conditions for the procedure

are described in ➁ to ➅ below.)

Execute the following procedure when the PIN bit is “0.”

•

LDM

#$00, S1

(Select slave receive mode)

LDA

—

(Take out slave address value)

SEI

(Interrupt disabled)

STA

(Write slave address value)

LDM

#$F0, S1

(Trigger RESTART condition generation)

CLI

(Interrupt enabled)

•

➁ Select the slave receive mode when the PIN bit is “0.” Do not write

“1” to the PIN bit. Neither “0” nor “1” is specified for the writing to

the BB bit.

The TRX bit becomes “0” and the SDA pin is released.

➂ The SCL pin is released by writing the slave address value to the

I2C data shift register. Use “STA,” “STX” or “STY” of the zero page

addressing instruction for writing.

➃ Use “LDM” instruction for setting trigger of RESTART condition

generation.

➄ Write the slave address value of ➂ and set trigger of RESTART

condition generation of ➃ continuously, as shown in the procedure

example.

➅ Disable interrupts during the following two process steps:

• Write slave address value

• Trigger RESTART condition generation

(4) STOP condition generating procedure

➀ Procedure example (The necessary conditions for the procedure

are described in ➁ to ➃ below.)

•

SEI

(Interrupt disabled)

LDM #$C0, S1

(Select master transmit mode)

NOP

(Set NOP)

LDM #$D0, S1

(Trigger STOP condition generation)

CLI

(Interrupt enabled)

•

➁ Write “0” to the PIN bit when master transmit mode is selected.

➂ Execute “NOP” instruction after master transmit mode is set. Also,

set trigger of STOP condition generation within 10 cycles after se-

lecting the master trasmit mode.

➃ Disable interrupts during the following two process steps:

• Select master transmit mode

• Trigger STOP condition generation

(5) Writing to I2C status register

Do not execute an instruction to set the PIN bit to “1” from “0” and an

instruction to set the MST and TRX bits to “0” from “1” simultaneously

as it may cause the SCL pin the SDA pin to be released after about

one machine cycle. Also, do not execute an instruction to set the

MST and TRX bits to “0” from “1” when the PIN bit is “1,” as it may

cause the same problem.

(6) Process after STOP condition generation

Do not write data in the I2C data shift register S0 and the I2C status

the STOP condition in the master mode. Doing so may cause the

STOP condition waveform from being generated normally. Reading

the registers does not cause the same problem.

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