I 2 C B�S Comm�Nication - Holtek HT68F Series Manual

HT68F20/HT68F30/HT68F40/HT68F50/HT68F60
HT68FU30/HT68FU40/HT68FU50/HT68FU60
Enhanced I/O Flash Type 8-Bit MCU with EEPROM
H T X B i t
S C L P i n D e b o u n c e
D a t a i n L S B
S D A P i n C i r c u i t r y
M
U
E n a b l e / D i s a b l e A c k n o w l e d g e
C o n f i g u r a t i o n X
O p t i o n s
I C Bus Communication
2
Communication on the I
transmission, a data transmission and finally a STOP signal. When a START signal is placed on
the I C bus, all devices on the bus will receive this signal and be notified of the imminent arrival of
2
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
SIMC1 register will be set and an I
routine, the slave device must first check the condition of the HAAS bit to determine whether the
interrupt source originates from an address match or from the completion of an 8-bit data transfer.
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
steps to achieve this:
• Step 1
Set the SIM2~SIM0 and SIMEN bits in the SIMC0 register to "1" to enable the I
• Step 2
Write the slave address of the device to the I
• Step 3
Set the SIME and SIM Muti-Function interrupt enable bit of the interrupt control register to
enable the SIM interrupt and Multi-function interrupt.
Rev. 2.10
I C D a t a R e g i s t e r
2
( S I M D )
D i r e c t i o n C o n t r o l
S h i f t R e g i s t e r
D a t a O u t M S B
T r a n s m i t / R e c e i v e
C o n t r o l U n i t
I 2 C Block Diagram
C bus requires four separate steps, a START signal, a slave device address
2
C interrupt will be generated. After entering the interrupt service
2
C bus, the microcontroller must initialise the bus, the following are
2
C bus address register SIMA.
2
181
D a t a B u s
S l a v e A d d r e s s R e g i s t e r
( S I M A )
A d d r e s s A d d r e s s M a t c h
C o m p a r a t o r
H A A S B i t
R e a d / w r i t e S l a v e
S R W B i t
8 - b i t D a t a C o m p l e t e H C F B i t
D e t e c t S t a r t o r S t o p
H B B B i t
I C I n t e r r u p t
2
C bus.
2
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