maxq3212-emx+ Maxim Integrated Products, Inc., maxq3212-emx+ Datasheet - Page 18

• Manufacturer Part Number: maxq3212-emx+
• Description: Maxq3212 Microcontroller With Analog Comparator And Led Driver
• Manufacturer: Maxim Integrated Products, Inc.

Microcontroller with Analog Comparator
and LED Driver
The watchdog timer functions are described in the
MAXQ Family User’s Guide. Software can determine if
a reset is caused by a watchdog timeout by checking
the Watchdog Timer Reset Flag (WTRF) in the WDCN
register. Execution resumes at location 8000h following
a watchdog timer reset.
Asserting the external RESET pin low causes the
device to enter the reset state. The external reset func-
tions as described in the MAXQ Family User’s Guide.
Execution resumes at location 8000h after the RESET
pin is released. The external system reset function is
enabled by default on a power-on reset, but can be
disabled and the pin used as general-purpose I/O by
setting the Reset Pin Disable (RSTD) bit. The system
designer is cautioned not to disable the reset pin early
in the software as it could disable future JTAG access
and/or bootloader capability.
Figure 3. Type D Port Pin Schematic
18
____________________________________________________________________
PI.x OR SF INPUT
SF DIRECTION
FLAG
SF OUTPUT
SF ENABLE
PD.x
PO.x
INTERRUPT
Watchdog Timer Reset
External System Reset
FLAG
CIRCUIT
DETECT
EIES.x
The microcontroller uses a form of Type D bidirectional
I/O pins described in the MAXQ Family User’s Guide.
Each port has eight independent, general-purpose I/O
pins and three configure/control registers. Many pins
support alternate functions such as timers or interrupts,
which are enabled, controlled, and monitored by dedi-
cated peripheral registers. Using the alternate function
automatically converts the pin to that function. The I/O
pins on this device employ an optional “keeper” latch
that helps to maintain the input pin state in the absence
of external drive sources.
Port 0.7 is a special pin with a stronger pulldown capa-
bility to drive devices such as LEDs. It operates and is
configured the same as other pins.
Type D port pins have Schmitt Trigger receivers and
full CMOS output drivers, and can support special
functions. The pin is either tri-stated or weak pullup
when defined as an input, dependent on the state of
the corresponding bit in the output register. One pin of
the device has interrupt capability.
MAXQ3212
I/O PAD
V
DDIO
V
WEAK
DD
PIN.x
I/O Ports