Maxim Integrated MAXQ7667 - Manual (Page 3)

___________________________________________________________________________________ Maxim Integrated Products 1-1
MAXQ7667 User’s Guide
SECTION 1: OVERVIEW
The MAXQ7667 is a smart data-acquisition system based on the MAXQ ® microcontroller (µC) with integrated peripheral functions for
ultrasonic, time-of-flight, distance measurement. The MAXQ processor is a high-performance reduced instruction set computing (RISC)
core µC designed for efficient peripheral multitasking applications. The MAXQ core contains a 16-bit Harvard Architecture RISC core
that executes instructions in a single clock cycle from instruction fetch to cycle completion. The MAXQ core works without the aid of
an instruction prefetch pipeline. This streamlines the entire instruction fetch, decode, and execute task, which dramatically improves
code density, memory access benchmarks, and multitasking interrupt-based latency. The MAXQ architecture was designed specifi-
cally for analog I/O and peripheral multitasking applications.
As a member of the MAXQ family of 16-bit RISC µCs, the MAXQ7667 is ideal for low-cost, low-power embedded applications such as
• Automotive Parking
• Vehicle Security
• Industrial Processing
• Automation
• Handheld Devices
The flexible, modular architecture design used in these µCs allows development of targeted products for specific applications with min-
imal effort.
The MAXQ7667 includes the following general-purpose peripherals: maximum 16MHz (factory default is 13.5MHz) RC oscillator, crys-
tal oscillator support, watchdog timer, schedule timer, three general-purpose timer/counters, two 8-bit GPIO ports, SPI™ port, JTAG
port, LIN-capable UART, 12-bit ADC with five input channels, and a voltage reference. These modules are useful for communication,
diagnostics, and miscellaneous support.
Peripherals dedicated to ultrasonic measurement include a burst signal generator and echo signal processing for transducer fre-
quencies from 25kHz to 100kHz. When triggered, the BURST output supplies the specified number of transducer excitation cycles at
the specified frequency and duty cycle. Echo signals are received and digitized by a low noise amplifier (LNA) and 16-bit sigma-delta
ADC that together provide a variable gain ranging from 38dB to 60dB. Following the ADC is a digital bandpass filter, demodulator, and
digital lowpass filter with a 16-bit output. Supporting both the burst generator and echo reception is a programmable, PLL frequency
synthesizer that supplies both the burst frequency and the clock for the digital filters. Using the PLL for both burst transmission and
echo reception ensures that the bandpass filter always tracks the transducer excitation. Both the digital filtering and the clock synthe-
sis are done without CPU intervention. All the CPU power is available for other tasks.
MAXQ7667 Features
• 16-Bit Single-Cycle RISC Core Processor
• Simultaneous Instruction/Data Harvard Memory Architecture
• 32KB Flash Memory
• 4KB Data RAM
• Utility ROM
• Burst-Pulse Generation Using Fractional N Frequency Synthesis
• Low-Noise, Variable Gain, Echo Receive Amplifier
16-Bit Sigma-Delta ADC for Digitizing the Echo
Digital Bandpass Filter that Tracks the Burst Frequency
Digital Demodulator and Lowpass Filter to Create an Echo Envelope with 16-Bit Resolution
FIFO Stores Up to 8 Readings from the Lowpass Filter
Digital Comparator Trips When Output of Lowpass Filter Reaches the Programmed Value
• 12-Bit, 5-Channel SAR ADC
• 2.5V Reference
MAXQ is a registered trademark of Maxim Integrated Products, Inc.
SPI is a trademark of Motorola, Inc.