maxq7667 Maxim Integrated Products, Inc., maxq7667 Datasheet - Page 26

• Manufacturer Part Number: maxq7667
• Description: 16-bit, Risc, Microcontroller-based, Ultrasonic Distance-measuring System
• Manufacturer: Maxim Integrated Products, Inc.

16-Bit, RISC, Microcontroller-Based,
Ultrasonic Distance-Measuring System
Figure 13. Port 0 Digital I/O Basic Circuitry. Port 1 Circuitry is the Same as Port 2.
Connect bypass capacitors at each power-supply input
as close as possible to the device. Use a bypass
capacitor less than 0.47µF on DVDDIO. For most appli-
cations, 0.1µF bypass capacitors are adequate.
Power supplies DVDD, AVDD, and DVDDIO each
include a brownout monitor/supervisor that alerts the
µC when their corresponding supply voltages drop
below the interrupt threshold. Activate each brownout
monitor independently using the corresponding
brownout enable bits: VDBE, VIBE, and VABE.
In reset mode, no instruction execution occurs and all
inputs/outputs return to their default states. Code exe-
cution resumes at address 8000h (in the utility ROM)
once the reset condition is removed.
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SF DIRECTION
SF OUTPUT
SF ENABLE
SF INPUT
PI0._ OR
PD0._
PO0._
Supply Brownout Monitor
MAXQ7667
FLAG
MUX
MUX
PR0._
PS0._
INTERRUPT
FLAG
I/O PAD
Reset
CIRCUIT
DETECT
Four different sources reset the MAXQ7667: POR,
watchdog timer reset, external reset, and internal sys-
tem reset.
During normal operation, force RESET low for at least
four system clock cycles for an external reset. Set the
ROD bit in the SC register, while the SPE bit in the ICDF
register is set, for an internal system reset. See Section
16 of the MAXQ7667 User’s Guide .
The MAXQ7667 includes a DVDD voltage supervisor to
control the µC POR. On power-up, internal circuitry
pulls RESET low and resets all the internal registers.
RESET is held low for the duration of the power-on
delay after V
old. The internal RC oscillator starts up and software
execution begins at the reset vector location 8000h
immediately after the device exits POR while RESET is
EIE0._
EIES0._
DVDD
rises above the DVDD reset thresh-
DGND
DVDDIO
100ΩK
100ΩK
DGND
Power-On Reset (POR)
P0._