Holtek HT66F20 Manual page 238

UART Module A.C. Characteristics
Symbol
t SCK Period (t
CP
t SCK High Time
CH
t SCK Low Time
CL
t SCS High P�lse Width
CSW
t SCS to SCK Set�p Time
CSS
t SCS to SCK Hold Time
CSH
t SDI to SCK Set�p Time
SDS
t SDI to SCK Hold Time
SDH
t SPI O�tp�t Rise Time
R
t SPI O�tp�t Fall Time
F
t SPI Data O�tp�t Delay Time
W
UART Module Functional Description
The embedded UART Module is full-duplex asynchronous serial communications UART interface
that enables communication with external devices that contain a serial interface. The UART
function has many features and can transmit and receive data serially by transferring a frame of
data with eight or nine data bits per transmission as well as being able to detect errors when the
data is overwritten or incorrectly framed. Interconnection between the MCU and the UART module
is implemented by internally connecting the MCU Master SPI interface to the UART Slave SPI
interface. All data transmissions and receptions between MCU and UART module including UART
commands are conducted along this interconnected SPI interface. The UART function control is
executed by the MCU using its SPI Master serial interface. The UART module contains its own
independent interrupt which can be used to indicate when a data reception occurs or when a data
transmission has terminated.
UART Module Internal Signal
In addition to the TX and RX external pins described above there are other MCU to UART Module
interconnecting lines that are described in the following table. Note that these lines are internal to
the device and are not bonded to external pins.
Rev. 2.50
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
Test Conditions
Parameter
V Conditions
DD
3.0V
+ t )
CH CL
5.0V
3.0V
5.0V
3.0V
5.0V
3.0V
5.0V
—
—
—
—
—
—
—
238
A/D Flash MCU with EEPROM
Min. Typ. Max.
— 62.5 —
— 50.0 —
— 28 —
— 22 —
— 28 —
— 22 —
— 500 —
— 400 —
— �00 —
— 0 —
— �00 —
— 0 —
— — �0
— — �0
— 0 —
Ta=25°C
Unit
— ns
— ns
— ns
— ns
— ns
— ns
— ns
— ns
— ns
— ns
— ns
— ns
— ns
— ns
— ns
��ne 22� 20��