Under considerations to regional surroundings, laws and regulations, communication efficiency, interference and transmission cost, this study proposes a wireless ARM-based automatic meter reading and control system (WAMRCS). The WAMRCS uses sampling circuits and A/D convertor to transfer analog signal of voltage and current into digital data. The digital data then send to embedded system to compute power parameters. This embedded system will send power parameters to regional monitoring and control center of utility company via wireless module connected with it. This WAMRCS applied on distribution automation can save personnel expense of hiring reading-meter workers and can be free from human involvement; more over it can save large man power from keying utility usage into data base.
2.1 BLOCK DIAGRAM:
LPC 2148 ARM PROCESSOR
3.1 LPC 2148 CPU:
The LPC2148 microcontrollers are based on a 32/16 bit ARM7TDMI-S CPU with real-time emulation and embedded trace support, that combines the microcontroller with embedded high speed flash memory ranging from 32 kB to 512 kB. A 128-bit wide memory interface and unique accelerator architecture enable 32-bit code execution at the maximum clock rate. For critical code size applications, the alternative 16-bit Thumb mode reduces code by more than 30 % with minimal performance penalty. Due to their tiny size and low power consumption, LPC2148 are ideal for applications where miniaturization is a key requirement, such as access control and point-of-sale. Fig 3.1 shows the block diagram of ARM LPC 2148 processor.
• 16/32-bit ARM7TDMI-S microcontroller in a tiny LQFP64 package.
• 8 to 40 kB of on-chip static RAM and 32 to 512 kB of on-chip flash program memory.
• 128 bit wide interface/accelerator enables high speed 60 MHz operation.
• In-System/In-Application Programming (ISP/IAP) via on-chip boot-loader software.
• Single flash sector or full chip erase in 400 ms and programming of 256 bytes in 1 ms.
• Embedded ICE RT and Embedded Trace interfaces offer real-time debugging with the on-chip Real Monitor software and high speed tracing of instruction execution.
• USB 2.0 Full Speed compliant Device Controller with 2 kB of endpoint RAM. In addition, the LPC2146/8 provides 8 kB of on-chip RAM accessible to USB by DMA.
• One or two (LPC2141/2 vs. LPC2144/6/8) 10-bit A/D converters provide a total of 6/14 analog inputs, with conversion times as low as 2.44 μs per channel.
• Single 10-bit D/A converter provides variable analog output.
• Two 32-bit timers/external event counters (with four capture and four compare channels each), PWM unit (six outputs) and watchdog.
• Low power real-time clock with independent power and dedicated 32 kHz clock input.
• Multiple serial interfaces including two UARTs (16C550), two Fast I2C-bus
• (400 Kbit/s), SPI and SSP with buffering and variable data length capabilities.
• Vectored interrupt controller with configurable priorities and vector addresses.
• Up to 45 of 5 V tolerant fast general purpose I/O pins in a tiny LQFP64 package.
• Up to nine edge or level sensitive external interrupt pins available.
• 60 MHz maximum CPU clock available from programmable on-chip PLL with settling time of 100 μs.
• On-chip integrated oscillator operates with an external crystal in range from 1 MHz to 30 MHz and with an external oscillator up to 50 MHz.
• Power saving modes include idle and Power-down.
• Individual enable/disable of peripheral functions as well as peripheral clock scaling for additional power optimization.
• Processor wake-up from Power-down mode via external interrupt, USB, Brown-Out Detect (BOD) or Real-Time Clock (RTC).
• Single power supply chip with Power-On Reset (POR) and BOD circuits: