Maxim Integrated MAXQ7667 - Manual (Page 78)

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MAXQ7667 User’s Guide
SECTION 5: GENERAL-PURPOSE I/O MODULE
The MAXQ7667 smart data-acquisition microcontroller provides 2 ports (P0 and P1) for general-purpose I/O, each with 8 port pins. The
port pins have the following features:
• All pins support alternate and special functions
• CMOS-compatible I/O levels to DVDDIO and GND rails
• User-selectable programmable drive strength when configured as output
• User-selectable resistive pull direction when configured as input
• Rising or falling edge selectable interrupt or wakeup inputs on all digital I/O pins
• Low leakage
5.1 Architecture
5.1.1 Enhanced Type D I/O Port
The MAXQ7667 supports the enhanced Type D port. Enhanced Type D is a bidirectional I/O port that incorporates Schmitt trigger
receivers and full CMOS output drivers, and can support alternate functions. All enhanced Type D pins also have interrupt capability.
All port pins can support special function (SF). Enabling the special function automatically converts the pin to that function. Special
function is usually implemented in another functional module and supported by individual enable or status bits.
Figure 5-1 illustrates an enhanced Type D port pin function. The pin logic of each port pin is identical.
When the ports are configured as an output, the output drive strength can be set to either 1mA or 2mA by setting the PS0 and PS1
registers. When the ports are configured as an input, the resistive pull direction (either pullup or pulldown) can be set by the PR0 and
PR1 registers. The typical value is 150k Ω.
Figure 5-1. Enhanced Type D Port Pin Schematic
SF ENABLE
PRn.x
PIn.x OR SF INPUT
PDn.x
SF DIRECTION
POn.x
SF OUTPUT
PSn.x
M
U
X
M
U
X
FLAG EIEn.x
EIESn.x
DETECT
CIRCUIT
INTERRUPT
FLAG
n = PORTS
x = PIN
150k Ω
DVDDIO
PORT PIN
150k Ω