Owner's manual

A/T8xC5121

4164G–SCR–07/06

Reset Addresses On reset, the SADDR, SADEN register are initialized to 00h, i.e. the given and broad-

cast addresses are XXXX XXXXb (all don’t care bits). This ensures that the serial port is

backwards compatible with the 80C51 microcontrollers that do not support automatic

address recognition.

UART Output Configuration

Voltage Level The I/O Ports of UART are powered by the EV

Regulator. The voltage of this regulator

can be:

• Automatically controlled by the microcontroller which adapt the power supply level

versus the OE input voltage level.

• Set at three defined levels (1.8V, 2.3V or 2.8V)

These configurations are defined with the EVAUTO and VEXT0,VEXT1 Bits of SIOCON

Output Enable Function The UART outputs (Tx, T0) can be controlled by the Output Enable input.

The Bits PMOSEN0 and PMOSEN1 in SIOCON Register are used to control this output.

PMOSEN0

PMOSEN1

(P3.3)

PMOS Comman

(Active at 1)

SFR

Value