HT56R26 View Datasheet(PDF) - Holtek Semiconductor
Part Name
Description
MFG CO.
'HT56R26' PDF : 134 Pages View PDF
HT56R22/HT56R23/HT56R24/HT56R25/HT56R26
S T A R T s ig n a l
fro m M a s te r
S e n d s la v e a d d r e s s
a n d R /W b it fr o m M a s te r
A c k n o w le d g e
fr o m s la v e
S e n d d a ta b y te
fro m M a s te r
A c k n o w le d g e
fr o m s la v e
S T O P s ig n a l
fro m M a s te r
There are several configuration options associated
with the I2C interface. One of these is to enable the
function which selects the SIM pins rather than normal
I/O pins. Note that if the configuration option does not
select the SIM function then the SIMEN bit in the
SIMCTL0 register will have no effect. A configuration
option exists to allow a clock other than the system
clock to drive the I2C interface. Another configuration
option determines the debounce time of the I2C inter-
face. This uses the internal clock to in effect add a
debounce time to the external clock to reduce the pos-
sibility of glitches on the clock line causing erroneous
operation. The debounce time, if selected, can be
chosen to be either 1 or 2 system clocks.
SIM
Function
SIM function
I2C clock
SIM interface or SEG pins
I2C runs without internal clock
Disable/Enable
I2C debounce
No debounce, 1 system clock;
2 system clocks
I2C Interface Configuration Options
· I2C Registers
There are three control registers associated with the
I2C bus, SIMCTL0, SIMCTL1 and SIMAR and one
data register, SIMDR. The SIMDR register, which is
shown in the above SPI section, is used to store the
data being transmitted and received on the I2C bus.
Before the microcontroller writes data to the I2C bus,
the actual data to be transmitted must be placed in the
SIMDR register. After the data is received from the I2C
bus, the microcontroller can read it from the SIMDR
register. Any transmission or reception of data from
the I2C bus must be made via the SIMDR register.
Note that the SIMAR register also has the name
SIMCTL2 which is used by the SPI function. Bits
SIMIDLE , SIMEN and bits SIM0~SIM2 in register
SIMCTL0 are used by the I2C interface. The SIMCTL0
register is shown in the above SPI section.
¨ SIMIDLE
The SIMIDLE bit is used to select if the I2C interface
continues running when the device is in the IDLE
mode. Setting the bit high allows the I2C interface to
maintain operation when the device is in the Idle
mode. Clearing the bit to zero disables any I2C op-
erations when in the Idle mode.
This SPI/I2C idle mode control bit is located at
CLKMOD register bit4.
¨ SIMEN
The SIMEN bit is the overall on/off control for the I2C
interface. When the SIMEN bit is cleared to zero to
disable the I2C interface, the SDA and SCL lines will
be in a floating condition and the I2C operating cur-
rent will be reduced to a minimum value. In this con-
dition the pins can be used as SEG functions. When
the bit is high the I2C interface is enabled. The SIM
configuration option must have first enabled the SIM
interface for this bit to be effective. Note that when
the SIMENbit changes from low to high the contents
of the I2C control registers will be in an unknown
condition and should therefore be first initialised by
the application program.
¨ SIM0~SIM2
These bits setup the overall operating mode of the
SIM function. To select the I2C function, bits SIM2~
SIM0 should be set to the value 110.
D a ta B u s
I2 C D a ta R e g is te r
(S IM D R )
S la v e A d d r e s s R e g is te r
(S IM A R )
S C L P in
S D A P in
H T X B it
D ir e c tio n C o n tr o l
A d d re s s
C o m p a ra to r
A d d re s s M a tc h
H A A S B it
D a ta in L S B
M
D a ta O u t M S B
S h ift R e g is te r
U
X E n a b le /D is a b le A c k n o w le d g e
R e a d /w r ite S la v e
T r a n s m it/R e c e iv e
C o n tr o l U n it
8 - b it D a ta C o m p le te
D e te c t S ta rt o r S to p
I2C Block Diagram
S R W B it
H C F B it
H B B B it
I2C In te rru p t
Rev. 1.30
73
December 26, 2014
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