CML - Analogue & Digital PMR/LMR - CMX7861

The CMX7861 FirmCODEC ® is a full-featured analogue front end for DSP/Microcontroller based systems. The device is a combination of codec, embedded signal processing and auxiliary system support functions, allowing simple interfacing between analogue and digital systems.

Single-ended and differential interface options are provided and I/Q-based operation is supported. The device can also be used in radio systems operating with channel bandwidths up to 50kHz, interfacing RF devices to baseband DSP/microcontroller, performing the main data conversion and auxiliary operations for monitoring and control.

Fully-programmable, on-chip independent dual-channel digital channel filters can be utilised for signal conditioning purposes. An Intelligent four channel SAR, ADC, four independent DACs and GPIO sub-systems perform valuable functions and minimise host interaction and host I/O resources.

Two synthesised system clock generators develop clock signals for off-chip use. The C-BUS/SPI master interface expands host C-BUS/SPI ports to control external devices.

The CMX7861 utilises CML’s proprietary FirmASIC® component technology that enables on-chip subsystems to be configured by a Function Image™ data file, which is uploaded during device initialisation and defines the device's function and feature set.

The Function Image™ can be loaded automatically from a host microcontroller over the C-BUS serial interface or from an external memory device. The device's functions and features can be enhanced by subsequent Function Image™ releases, facilitating in-the-field upgrades.

It is possible to design custom transmit filters for use when the CMX7861 is operating in Codec mode. The link under 'Resources' at the top of this page accesses an Application Note which describes how do do this using Scilab software.

Block Diagram


  • Dual Channel Codecs
  • Can operate in modem or codec mode
    • Two ADCs 16 bit
    • Two DACs 14 bit
    • Programmable input and output gain
    • Differential /single-ended inputs/outputs
  • Digital Channel Filters
    • Two fully-programmable digital filters
    • Filter design and configuration support
  • Auxiliary GPIO
  • Auxiliary Synthesised Clock Generators
  • C-BUS Host Serial Interface
  • Master SSP Interface


  • General-purpose DSP analogue/digital interface
    • Sensors
    • Control systems
    • Telemetry/SCADA/data modems
  • High Performance Narrowband Data Radio
    • DMR
    • APCO P25
    • Software Defined Radio (SDR)
    • 6.25kHz to 25kHz RF channel spacings
    • Worldwide compatibility
  • High Performance I/Q Radio Interface

Supply Requirement:

  • 3.0 to 3.6 V