sc18is602 NXP Semiconductors, sc18is602 Datasheet - Page 10

• Manufacturer Part Number: sc18is602
• Description: Sc18is602/sc18is603 I?c-bus To Spi Bridge
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SC18IS602_603_3
Product data sheet
7.1.11.1 Quasi-bidirectional output configuration
7.1.11 GPIO Configuration - Function ID F7h
The pins defined as GPIO may be configured by software to one of four types on a
pin-by-pin basis. These are: quasi-bidirectional, push-pull, open-drain, and input-only.
Two bits select the output type for each port pin.
Table 9.
[1]
Table 10.
[1]
The SSn pins defined as GPIO, for example SS0.0 and SS0.1, may be configured by
software to one of four types. These are: quasi-bidirectional, push-pull, open-drain, and
input-only. Two configuration bits in GPIO Configuration register for each pin select the
type for each pin. A pin has Schmitt-triggered input that also has a glitch suppression
circuit. For SC18IS603, the SS3 pin defined as GPIO is non-existent.
Quasi-bidirectional outputs can be used both as an input and output without the need to
reconfigure the pin. This is possible because when the pin outputs a logic HIGH, it is
weakly driven, allowing an external device to pull the pin LOW. When the pin is driven
LOW, it is driven strongly and able to sink a large current. There are three pull-up
transistors in the quasi-bidirectional output that serve different purposes.
One of these pull-ups, called the ‘very weak’ pull-up, is turned on whenever the port latch
for the pin contains a logic 1. This very weak pull-up sources a very small current that will
pull the pin HIGH if it is left floating.
Bit
7
6
5
4
3
2
1
0
SS3.1
SS3.1 and SS3.0 do not exist in the SC18IS603.
SS3.1 and SS3.0 do not exist in the SC18IS603.
7
[1]
Symbol
SS3.1
SS3.0
SS2.1
SS2.0
SS1.1
SS1.0
SS0.1
SS0.0
GPIO Configuration (F7h) bit allocation
GPIO Configuration (F7h) bit description
SS3.0
6
[1]
[1]
[1]
Rev. 03 — 13 August 2007
Description
SS2.1
SS3[1:0] = 00: quasi-bidirectional
SS3[1:0] = 01: push-pull
SS3[1:0] = 10: input-only (high-impedance)
SS3[1:0] = 11: open-drain
SS2[1:0] = 00: quasi-bidirectional
SS2[1:0] = 01: push-pull
SS2[1:0] = 10: input-only (high-impedance)
SS2[1:0] = 11: open-drain
SS1[1:0] = 00: quasi-bidirectional
SS1[1:0] = 01: push-pull
SS1[1:0] = 10: input-only (high-impedance)
SS1[1:0] = 11: open-drain
SS0[1:0] = 00: quasi-bidirectional
SS0[1:0] = 01: push-pull
SS0[1:0] = 10: input-only (high-impedance)
SS0[1:0] = 11: open-drain
5
SS2.0
4
SS1.1
3
SC18IS602/603
SS1.0
2
I
2
C-bus to SPI bridge
SS0.1
© NXP B.V. 2007. All rights reserved.
1
SS0.0
10 of 25
0