
Rev. 1.21
116
�ove��e� ��� 2�1�
Rev. 1.21
11�
�ove��e� ��� 2�1�
HT66F488/HT66F489
A/D Flash MCU with EEPROM
HT66F488/HT66F489
A/D Flash MCU with EEPROM
SPI Master/Slave Connection
SPI Block Diagram
SPI Register
There are three internal registers which control the overall operation of the SPI interface. These are
the SIMD data register and two control registers SIMC0 and SIMC2.
Register
Name
Bit
7
6
5
4
3
2
1
0
SIMC�
SIM2
SIM1
SIM�
—
SIMDB�C1 SIMDB�C� SIME�
SPIICF
SIMD
D�
D6
D5
D4
D3
D2
D1
D�
SIMC2
D�
D6
CKPOLB
CKEG
MLS
CSE�
WCOL
TRF
SIM Registers List
The SIMD register is used to store the data being transmitted and received. The same register is used
by both the SPI and I
2
C functions. Before the devices write data to the SPI bus, the actual data to
be transmitted must be placed in the SIMD register. After the data is received from the SPI bus, the
device can read it from the SIMD register. Any transmission or reception of data from the SPI bus
must be made via the SIMD register.