mc68hc908bd48 Freescale Semiconductor, Inc, mc68hc908bd48 Datasheet - Page 200

• Manufacturer Part Number: mc68hc908bd48
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

DDC12AB Interface
Data Sheet
200
NAKIF — No Acknowledge Interrupt Flag
BB — Bus Busy Flag
MAST — Master Control Bit
MRW — Master Read/Write
This flag is only set in master mode (MAST = 1) when there is no
acknowledge bit detected after one data byte or calling address is
transferred. This flag also clears MAST. NAKIF generates an interrupt
request to CPU if the DIEN bit in DCR is also set. This bit is cleared
by writing "0" to it or by reset.
This flag is set after a start condition is detected (bus busy), and is
cleared when a stop condition (bus idle) is detected or the DDC is
disabled. Reset clears this bit.
This bit is set to initiate a master mode transfer. In master mode, the
module generates a start condition to the SDA and SCL lines,
followed by sending the calling address stored in DADR.
When the MAST bit is cleared by NAKIF set (no acknowledge) or by
software, the module generates the stop condition to the lines after
the current byte is transmitted.
If an arbitration loss occurs (ALIF = 1), the module reverts to slave
mode by clearing MAST, and releasing SDA and SCL lines
immediately.
This bit is cleared by writing "0" to it or by reset.
This bit will be transmitted out as bit 0 of the calling address when the
module sets the MAST bit to enter master mode. The MRW bit
determines the transfer direction of the data bytes that follows. When
it is "1", the module is in master receive mode. When it is "0", the
module is in master transmit mode. Reset clears this bit.
1 = No acknowledge bit detected
0 = Acknowledge bit detected
1 = Start condition detected
0 = Stop condition detected or DDC is disabled
1 = Master mode operation
0 = Slave mode operation
1 = Master mode receive
0 = Master mode transmit
DDC12AB Interface
MC68HC908BD48
Freescale Semiconductor
—
Rev. 2.1