AN EMBEDDED SINGLE CHIPTEMPERATURE
CONTROLLER DESIGN
J. Jayapandian and Usha Rani Ravi
Design Development & Services Section, Materials Science Division
Indira Gandhi Centre for Atomic Research, Kalpakkam -603 102. Tamil Nadu. India
ABSTRACT
This paper describes a single chip embedded temperature controller design programmed in a single Programmable System on Chip (PSoC); a mixed array logic consists of analog,digital and digital communication blocks within in it. The virtual instrument control program written in LabVIEW ver.7.1, a graphical language, provides user friendly menu driven window based control panel, interacts with the single PSoC chip design for sensing and controlling the temperature. This simple cost effective embedded design finds potential application in laboratory as well as in industries. This deign can also be made as a standalone system without PC by programming LED/ LCD display and key pad attachment modules in same PSoC chip 1.1 INTRODUCTION
The advent of intelligent programmable embedded silicon designs provides the ability to implement any required hardware programmatically for the design automation in industries and laboratories. Recent trend in laboratory as well as in industrial automation designs uses minimal hardware and maximum support of software. The programmable embedded components and application software available in the market enables the designer for user-friendly cost effective design solution for any system automation. Temperature controllers are playing vital role in industries and laboratories. To accurately control process temperature without extensive operator involvement, a temperature control system relies upon a controller, which accepts a temperature sensor such as a thermocouple or RTD as input. It compares the actual temperature to the desired control temperature, or set point, and
provides an output to a control element. The controller is one of the major parts of the entire control system,and the whole system should be analyzed in selecting the proper controller. This paper describes a novel single chip temperature controller design with Cypress Microsystems Programmable System on Chip (PSoC). Virtual instrument control program written in LabVIEW ver.7.1 interacts with the embedded PSoC design and senses and controls the temperature offurnace / load.An embedded single chip temperature controller design
Fig. 1 : Block diagram of Programmable System on Chip (PSoC) internal blocks
1.2 PROGRAMMABLE SYSTEM ON CHIP (PSoC)
While selecting a microcontroller, it must have an easy and inexpensive interface to sensors, communication interfaces, and more. Cypress’ Programmable System-On-Chip (PSoC) architecture offers a flexible, economical solution for a wide variety of applications. This paper describes the design of a temperature controller on a single CY8C27143, 8 pin PSoC chip. As shown in fig.1, it features four main areas: PSoC core, digital system, analog system, and system resources including in/out ports.
This architecture allows the user to create customized peripheral configurations that match the requirements of each individual application. The UART interface, coupled with configurable analog and digital peripherals makes the CY8C27143 truly universal in its connections to the external world. The PSoC core includes: an M8C microcontroller; 32 Kbytes of program flash memory; 2 Kbyte of data RAM; internal 24 MHz oscillator; sleep and watchdog timer; general-purpose input/ output pins (GPIO) allowing any pin to be used as digital input or output, and most pins to be used as analog inputs or outputs. Every pin can be used as a digital or analog interrupt. The digital system is made up of 8 digital PSoC blocks. Each block is an 8-bit resource that can be used alone or combined with other blocks to form peripherals. Possible peripherals include: PWMs (8- to 32-bit); PWMs with dead band (8- to 24-bit); counters (8- to 32-bit); UART 8-bit with selectable parity; SPI master and slave; cyclical redundancy checker/generator (8- to 32-bit); pseudo random sequence generators (8- to 32-bit). These digital blocks can be connected to any of the GPIO through a series of global buses. These buses also allow for signal multiplexing and performing logic operations. The analog system is made up of 12 configurable blocks, each comprising an op amp circuit allowing the creation of complex analog signal flows. Analog peripheralsare very flexible and can be customized to support specific application requirements. Some of the more common PSoC analog functions are: filters (2- and 4- pole band-pass, low-pass,and notch); amplifiers (up to 2, with selectable gain to 48x); instrumentation amplifiers (1with selectable gain to 93x); comparators (up to 2, with 16 selectable thresholds); DACs (up to 2, with 6- to 10-bit resolution); and SAR ADCs (up to two, with 6-bit resolution). Incombination with the digital blocks, additional functions can be created, including: incremental ADCs (up to 2, with 6- to 14-bit resolution); delta sigma ADC (1,with 8-bit resolution at 62.5ksps). The additional system resources provide additional capability useful for the complete system design.
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