ht82k70e-l Holtek Semiconductor Inc., ht82k70e-l Datasheet - Page 34

• Manufacturer Part Number: ht82k70e-l
• Description: I/o Type 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

After Power on, the contents of the SBDR register will be
in an unknown condition while the SBCR register will de-
fault to the condition below:
Note that data written to the SBDR register will only be
written to the TXRX buffer, whereas data read from the
SBDR register will actual be read from the register.
To enable the SPI bus, SBEN should be set high, then
SCK, SDI, SDO and SCS lines should all be zero, then
wait for data to be written to the SBDR (TXRX buffer)
register. For the Master Mode, after data has been writ-
ten to the SBDR (TXRX buffer) register then transmis-
sion or reception will start automatically. When all the
data has been transferred the TRF bit should be set. For
the Slave Mode, when clock pulses are received on
SCK, data in the TXRX buffer will be shifted out or data
on SDI will be shifted in.
To Disable the SPI bus SCK, SDI, SDO, SCS should be
floating.
Rev. 1.00
Bus Enable/Disable
CKS M1 M0 SBEN MLS CSEN WCOL TRF
0
1
1
0
0
0
SPI Interface Control Register
0
0
34
All communication is carried out using the 4-line inter-
face for both Master or Slave Mode. The timing diagram
shows the basic operation of the bus.
The CSEN bit in the SBCR register controls the SCS line
of the SPI interface. Setting this bit high, will enable the
SPI interface by allowing the SCS line to be active,
which can then be used to control the SPI interface. If
the CSEN bit is low, the SCS line will be in a floating con-
dition and can therefore not be used for control of the
SPI interface. The SBEN bit in the SBCR register must
also be high which will place the SDI line in a floating
condition and the SDO line high. If in the Master Mode
the SCK line will be either high or low depending upon
the clock polarity configuration option. If in the Slave
Mode the SCK line will be in a floating condition. If SBEN
is low then the bus will be disabled and SCS, SDI, SDO
and SCK will all be in a floating condition.
Operation
HT82K70E-L/HT82K76E-L
September 15, 2009