Spi Communication - Holtek HT45F23A Manual

HT45F23A/HT45F24A
TinyPower Flash MCU with OPA & Comparators
TM
CSEN: SPI SCS pin Control
Bit 2
0: Disable
1: Enable
The CSEN bit is used as an enable/disable for the SCS pin. If this bit is low, then the
SCS pin will be disabled and placed into a floating condition. If the bit is high the
SCS pin will be enabled and used as a select pin. Note that using the CSEN bit can be
disabled or enabled via configuration option.
WCOL: SPI Write Collision flag
Bit 1
0: No collision
1: Collision
The WCOL flag is used to detect if a data collision has occurred. If this bit is high it
means that data has been attempted to be written to the SIMD register during a data
transfer operation. This writing operation will be ignored if data is being transferred.
The bit can be cleared by the application program. Note that using the WCOL bit can
be disabled or enabled via configuration option.
Bit 0 TRF: SPI Transmit/Receive Complete flag
0: Data is being transferred
1: SPI data transmission is completed
The TRF bit is the Transmit/Receive Complete flag and is set "1" automatically when
an SPI data transmission is completed, but must set to "0" by the application program.
It can be used to generate an interrupt.

SPI Communication

After the SPI interface is enabled by setting the SIMEN bit high, then in the Master Mode, when
data is written to the SIMD register, transmission/reception will begin simultaneously. When the
data transfer is complete, the TRF flag will be set automatically, but must be cleared using the
application program. In the Slave Mode, when the clock signal from the master has been received,
any data in the SIMD register will be transmitted and any data on the SDI pin will be shifted into
the SIMD register. The master should output an SCS signal to enable the slave device before a
clock signal is provided. The slave data to be transferred should be well prepared at the appropriate
moment relative to the SCS signal depending upon the configurations of the CKPOLB bit and CKEG
bit. The accompanying timing diagram shows the relationship between the slave data and SCS signal
for various configurations of the CKPOLB and CKEG bits.
The SPI will continue to function even in the IDLE Mode.
Rev. 1.40 93 March 29, 2019