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HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
Bit 1
IAMWU
: I
2
C Address Match Wake Up Control
0: Disable
1: Enable
This bit should be set to 1 to enable the I
2
C address match wake up from the SLEEP
or IDLE Mode. If the IAMWU bit has been set before entering either the SLEEP or
IDLE mode to enable the I
2
C address match wake up, then this bit must be cleared by
the application program after wake-up to ensure correction device operation.
Bit 0
RXAK
: I
2
C Bus Receive acknowledge flag
0: Slave receive acknowledge flag
1: Slave do not receive acknowledge flag
The RXAK flag is the receiver acknowledge flag. When the RXAK flag is "0", it
means that a acknowledge signal has been received at the 9th clock, after 8 bits of data
have been transmitted. When the slave device in the transmit mode, the slave device
checks the RXAK flag to determine if the master receiver wishes to receive the next
byte. The slave transmitter will therefore continue sending out data until the RXAK
flag is "1". When this occurs, the slave transmitter will release the SDA line to allow
the master to send a STOP signal to release the I
2
C Bus.
I
2
C Bus Communication
Communication on the I
2
C bus requires four separate steps, a START signal, a slave device address
transmission, a data transmission and finally a STOP signal. When a START signal is placed on the
I
2
C bus, all devices on the bus will receive this signal and be notified of the imminent arrival of data
on the bus. The first seven bits of the data will be the slave address with the first bit being the MSB.
If the address of the slave device matches that of the transmitted address, the HAAS bit in the IICC1
register will be set and an I
2
C interrupt will be generated. After entering the interrupt service routine,
the slave device must first check the condition of the HAAS and IICTOF bits to determine whether
the interrupt source originates from an address match or from the completion of an 8-bit data
transfer completion or the I
2
C bus time-out occurrence. During a data transfer, note that after the
7-bit slave address has been transmitted, the following bit, which is the 8th bit, is the read/write bit
whose value will be placed in the SRW bit. This bit will be checked by the slave device to determine
whether to go into transmit or receive mode. Before any transfer of data to or from the I
2
C bus, the
microcontroller must initialise the bus, the following are steps to achieve this:
• Step 1
Configure the pin-shared I/O ports to I
2
C function pins and set the IICEN bit in the IICC0 register
to "1" to enable the I
2
C bus.
• Step 2
Write the slave address of the device to the I
2
C bus address register IICA.
• Step 3
Set IICE and the corresponding interrupt priority enable bit of the interrupt control registers to
enable the I
2
C interrupt and the related interrupt priority.