Embedded computer systems permeate all aspects of our daily lives.
Alarm clocks, coffee makers, digital watches, cell phones, and automobiles
are just a few of the devices that make use of embedded systems. The
design and development of such systems is unique, because the design
constraints are different for each system. Essential to the development of
an embedded system is an understanding of the hardware and software
used for development.
With more and more multi-frequency clocks being used in today's chips, especially in the communications field, it is often necessary to switch the source of a clock line while the chip is running.
Abstract: This application note presents an overview of the operational characteristics of accurate I²C real-time clocks (RTCs),including the DS3231, DS3231M, and DS3232. It focuses on general application guidelines that facilitate use of device resources forpower management, I²C communication circuit configurations, and I²C characteristics relative to device power-up sequences andinitializations. Additional discussions on decoupling are provided to support developing strategies for mitigating power-supply pushingof device frequency.
The P89LPC912/913/914 are single-chip microcontrollers in low-cost 14-pin packages, based on a high performance processor architecture that executes instructions in two to four clocks, six times the rate of standard 80C51 devices. Many system level functions have been incorporated into the P89LPC912/913/914 in order to reduce component count, board space, and system cost.
HIGH SPEED 8051 μC CORE
- Pipe-lined Instruction Architecture; Executes 70% of Instructions in 1 or 2
System clocks
- Up to 25MIPS Throughput with 25MHz System Clock
- 22 Vectored Interrupt Sources
MEMORY
- 4352 Bytes Internal Data RAM (256 + 4k)
- 64k Bytes In-System Programmable FLASH Program Memory
- External Parallel Data Memory Interface – up to 5Mbytes/sec
DIGITAL PERIPHERALS
- 64 Port I/O; All are 5V tolerant
- Hardware SMBusTM (I2CTM Compatible), SPITM, and Two UART Serial
Ports Available Concurrently
- Programmable 16-bit Counter/Timer Array with 5 Capture/Compare
Modules
- 5 General Purpose 16-bit Counter/Timers
- Dedicated Watch-Dog Timer; Bi-directional Reset
CLOCK SOURCES
- Internal Programmable Oscillator: 2-to-16MHz
- External Oscillator: Crystal, RC, C, or Clock
- Real-Time Clock Mode using Timer 3 or PCA
SUPPLY VOLTAGE ........................ 2.7V to 3.6V
- Typical Operating Current: 10mA @ 25MHz
- Multiple Power Saving Sleep and Shutdown Modes
100-Pin TQFP (64-Pin Version Available)
Temperature Range: –40°C to +85°C
AVR32801: UC3A3 Schematic Checklist Features • Power circuit • Reset circuit • USB connection • External bus interface • ABDAC sound DAC interface • JTAG and Nexus debug ports • clocks and crystal oscillators • MMC, SD-card, SDHC, SDIO and CE-ATA interface 1 Introduction A good hardware design comes from a proper schematic. Since UC3A3 devices have a fair number of pins and functions, the schematic for these devices can be large and quite complex. This application note describes a common checklist which should be used when starting and reviewing the schematics for a UC3A3 design.
