Rainbow Electronics T89C5121 - Manual (Page 84)

84
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
CC
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
Register.
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.
0
1
0
1
0
1
PMOSEN0
PMOSEN0
PMOSEN1
OE
(P3.3)
PMOS Command
(Active at 1)
SFR
Value
0
1