Rainbow Electronics T89C5121 - 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