HT67F60 datasheet(176/242 Pages) HOLTEK

176 / 242 page

Rev. 1.50

176

March 06 , 2012

Rev. 1.50

177

March 06 , 2012

HT67F30/HT67F40/HT67F50/HT67F60

TinyPowerTM A/D Flash Type 8-Bit MCU with LCD & EEPRO

I2C Bus Start Signal

The START signal can only be generated by the master device connected to the I2C bus and not by

the slave device. This START signal will be detected by all devices connected to the I2C bus. When

detected, this indicates that the I2C bus is busy and therefore the HBB bit will be set. A START

condition occurs when a high to low transition on the SDA line takes place when the SCL line

remains high.

Slave Address

The transmission of a START signal by the master will be detected by all devices on the I2C bus. To

determine which slave device the master wishes to communicate with, the address of the slave

device will be sent out immediately following the START signal. All slave devices, after receiving

this 7-bit address data, will compare it with their own 7-bit slave address. If the address sent out by

the master matches the internal address of the microcontroller slave device, then an internal I2C bus

interrupt signal will be generated. The next bit following the address, which is the 8th bit, defines

the read/write status and will be saved to the SRW bit of the SIMC1 register. The slave device will

then transmit an acknowledge bit, which is a low level, as the 9th bit. The slave device will also set

the status flag HAAS when the addresses match.

As an I2C bus interrupt can come from two sources, when the program enters the interrupt

subroutine, the HAAS bit should be examined to see whether the interrupt source has come from a

matching slave address or from the completion of a data byte transfer. When a slave address is

matched, the device must be placed in either the transmit mode and then write data to the SIMD

release the SCL line.

I2C Bus Read/Write Signal

The SRW bit in the SIMC1 register defines whether the slave device wishes to read data from the

I2C bus or write data to the I2C bus. The slave device should examine this bit to determine if it is to

be a transmitter or a receiver. If the SRW flag is "1" then this indicates that the master device wishes

to read data from the I2C bus, therefore the slave device must be setup to send data to the I2C bus as

a transmitter. If the SRW flag is "0" then this indicates that the master wishes to send data to the I2C

bus, therefore the slave device must be setup to read data from the I2C bus as a receiver.

I2C Bus Slave Address Acknowledge Signal

After the master has transmitted a calling address, any slave device on the I2C bus, whose own

internal address matches the calling address, must generate an acknowledge signal. The

acknowledge signal will inform the master that a slave device has accepted its calling address. If no

acknowledge signal is received by the master then a STOP signal must be transmitted by the master

to end the communication. When the HAAS flag is high, the addresses have matched and the slave

device must check the SRW flag to determine if it is to be a transmitter or a receiver. If the SRW flag

is high, the slave device should be setup to be a transmitter so the HTX bit in the SIMC1 register

should be set to "1". If the SRW flag is low, then the microcontroller slave device should be setup as

a receiver and the HTX bit in the SIMC1 register should be set to "0".

HT67F60 Datasheet(PDF) 176 Page - Holtek Semiconductor Inc

HT67F60 Datasheet(HTML) 176 Page - Holtek Semiconductor Inc

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