Calsoft Labs Case Studies
Product Development

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Operator Console for an EPABX


This case study showcases the development of an Operator console for a high end EPABX supporting voice and data communications. The console is Atmel's ARM 9 micro processor AT91SAM9263 running on embedded Linux.

Client

The Client is a Telecom product company based in Bangalore, India. Their core business is product development in the Broadband access domain covering Voice, Data & Video.

Challenge

The Client wanted to launch a high end EPABX supporting voice modules (both POTS and ISDN) and data modules. The client was looking for a console which would support 90 extensions, handle all voice related functionalities. The Console was also supported by a character LCD. The challenge was to integrate all these functions in a single box supporting Ethernet/RS422 communication interface, 90 voice extensions, and a solution which has provisions for future expansion

Solution

The Operator console is designed around Atmel's ARM 9 processor AT91SAM9263. With so many functions being integrated, the whole solution was split into multiple boards as below:

  • Mother board housing the CPU, memory, Ethernet, RS232, RS422, USB 2.0 and I2C interfaces for Keypad.
  • Telephone Line Unit (TLU) for handling voice calls from the EPABX or directly from the exchange in case of EPABX failure
  • User interface board for handling console LED and Console Keypad interfaces
  • Expansion Direct Station Selection unit (EDSS) for supporting 90 extensions

The Operating system chosen was Linux Kernel 2.6 from Timesys and following drivers were developed:

  • I2C driver
  • Keypad driver
  • Watchdog driver
  • Speaker phone driver
  • Driver for the DTMF generator
  • SPI driver for the DTMF generator
  • RS422 driver for communication with EPABX

Complete console application was developed in Linux and rigorous testing was done on the integrated unit to identify potential failure points

Technology

  • ARM 9, Ethernet (10/100), RS422, I2C, USB 2.0, SPI, DTMF & Linux 2.6

Hardware Setup:

Operator Console for an EPABX

Benefits

  • Highly reliable and rugged console
  • Supports both Ethernet and RS422 modes of Operation with auto switching between the two in case of failure
  • Embedded Linux Operating system for greater reliability
  • Modular design to support 30,60 and 90 extensions