Highly versatile communications controller
19 May 2004
Telecoms, Datacoms, Wireless, IoT
News & Events
The trend throughout the telecoms industry is to integrate more product functions onto fewer chips, with single-chip products being the ultimate target in many applications. The CMX850 from CML brings together the very low power modem technology developed for the CMX860/867/868 range with an enhanced version of the widely used 80C51 microcontroller. The result is a highly versatile, low power, communications controller.
The interfacing to external memory (ROM/Flash and SRAM), LCD controller, and keypad is very straightforward and removes the need for 'glue' logic in many applications. All of the standard 80C51 features are retained and access to enhancements occurs through special function registers (SFRs). The development of software, therefore, requires only a standard compiler and PROM emulator.
The on-chip modem is essentially the two port circuitry (line and phone) of the company's CMX860 but enhanced to V.22bis (2400/2400). Communication between modem and 80C51 takes place through a C-Bus emulation which is mapped into the 80C51's special function register area. Users of the CMX860/7/8 will recognise the format and have no difficulty in moving current software onto the 80C51 platform.
The company says much attention has been paid in the design of the CMX850 to reduce power consumption to an absolute minimum. Numerous powerdown options allow functional elements not currently in use to be turned off. The 80C51 main clock can be selected to run from 12 MHz down to 12 kHz, with external memory accesses shortened to conserve power as main clock speed is reduced.
Versatility has also been maximised by the introduction of seven additional sources of interrupt built around the new 80C51 functions. With the ability to wake the microcontroller from various powerdown states, these interrupts open up whole new regimes of power conservation.
The CMX850 is targeted at low power, battery operated terminals which need to access the PSTN to upload or download data. Examples are: SMS and ADSI terminals; telemetry and meter reading systems; security systems; feature phones; routers; EPOS terminals; e-mail and Internet appliances.
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