Holtek HT66F20 Manual page 236

UART Module Pin Description
Pin Name I/O
External UART RX serial data inp�t pin
RX I If UARTEN=� and RXEN=�� then RX is the UART serial data inp�t
If UARTEN=0 or RXEN=0� then RX is high impedance
External UART TX serial data o�tp�t pin
TX O If UARTEN=� and TXEN=�� then TX is the UART serial data o�tp�t
If UARTEN=0 or TXEN=0� then TX is high impedance
Internal Slave SPI Serial Data In Inp�t Signal
SDI I
Internally connected to the MCU Master SPI SDO o�tp�t signal
Internal Slave SPI Serial Data O�t O�tp�t Signal
SDO O
Internally connected to the MCU Master SPI SDI inp�t signal
Internal Slave SPI Serial Clock Inp�t Signal
SCK I
Internally connected to the MCU Master SPI SCK o�tp�t signal
Internal Slave SPI Device Select Inp�t Signal
SCS I
Internally connected to the MCU Master SPI SCS o�tp�t signal -- connected to p�ll high resistor
Internal Clock Inp�t Signal
CLKI I
Internally connected to the MCU Master PCK o�tp�t signal
Internal UART Interr�pt O�tp�t Signal
INT O Internally connected to the MCU Master PINT inp�t signal
A UART related interr�pt will generate a low p�lse signal on this line
NC — Implies that the pin is Not Connected and can therefore not be �sed.
Notes: The pin description for all pins with the exception of the UART TX and RX pins are described in the
preceding MCU section.
Rev. 2.50
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
Description
236 ��ne 22� 20��