Rainbow Electronics T89C5121 User Manual
Page 95
95
A/T8xC5121
4164G–SCR–07/06
Table 69. SIOCON Register
Serial Input Output Configuration Register
Register (91h)
Reset Value = 00XX 0000b
7
6
5
4
3
2
1
0
PMSOEN1
PMSOEN0
-
-
CPRES
RES
EVAUTO
VEXT0
VEXT1
Bit
Number
Bit
Mnemonic
Description
7 - 6
PMOSEN1
PMOSEN0
Output Enable function on Txd/P3.1 and T0/P3.4:
PMSOEN1 PMSOEN0
0
0
PMOS is always off (reset value)
0
1
PMOS is always driven according to P3.1 or P3.4 value
1
0
PMOS is driven only when OE is high
1
1
PMOS is driven only when OE is low
5 - 4
-
Reserved
The value read from this bit is indeterminate. Do not set this bit.
3
CPRES
RES
Card Presence pull-up resistor
0 Internal pull-up is connected
1 Internal pull-up is disconnected
2
EVAUTO
EVCC Auto setup
Set to enable the Automatic mode of EV
CC
regulator
Clear to disable the Automatic mode of EV
CC
regulator
1 - 0
VEXT0
VEXT1
EVCC voltage configuration:
VEXT0 VEXT1
0
0
Power-down, EV
CC
is external (reset value)
0
1
EV
CC
= 1.8V
1
0
EV
CC
= 2.3V
1
1
EV
CC
= 2.7V