CMX989
CDPD MAC and
Data Pump Processor
D/989/2 October 2001
Provisional Information
Features
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Reed-Solomon Encoder, Decoder and Error
Correction
MAC and Physical Layer Functions:
Minimize Host µController Burden and Power
Tx and Rx Byte-Wide CDPD Frame FIFOs
Applications
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CDPD (Cellular Digital Packet Data)
Terminals
PCMCIA/PC-Card Wireless Modem
Modules
Wireless Internet Terminals
Portable and Mobile Wireless Data
Terminals
Line Power/Battery Applications
19.2kbps (BT = 0.5) Full Duplex
GMSK Data Modems
Encapsulates/De-Encapsulates CDPD Frames
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to/from Over-Air Baseband Signals
Parallel Bus Hardware Interface to Host CPU
2.7V to 5.5V Supply, 28-Pin TSSOP Package
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1.1
Brief Description
The highly integrated CMX989 CDPD MAC and Data Pump Processor integrates complex CDPD MAC
and physical layer functions to serve as a core engine for high performance, low power CDPD terminal
designs. MAC layer functions decouple the host CPU from the CDPD airlink to simplify and reduce
CDPD protocol stack programming, free CPU capacity for applications, eliminate interface components,
and allow CPU sleep time for power savings. Physical layer functions mate MAC layer to baseband radio
signals with minimal host involvement. MAC and physical layer functions are intelligently coupled to
meet airlink timing requirements. For example: Tx emissions automatically start in synchronisation with
Forward Channel busy/idle status. The Rx CDPD frame FIFO is automatically managed to wait for valid
synchronization to occur when first started and after lost signal recovery.
The radio interface supports simple, low cost, VCO-based RF modulators and discriminator-based
receivers. Independent, programmable gain Tx outputs are provided for software trimming and
balancing of modulating signals.
The host CPU interface is FIFO based and organized in CDPD frames, to provide a simple programming
interface with low service latency requirements. Over-the-air frames are automatically encapsulated and
de-encapsulated and include complete Reed-Solomon encoding, decoding and error correction, colour
code insertion and related functions. Device status bits are accessible and may be individually
configured to interrupt the host via the parallel hardware interface. The CMX989 operates from a 2.7V to
5.5V supply over -40 to 85°C and comes in a 28-pin TSSOP package (CMX989E1).
©
2001 Consumer Microcircuits Limited
CMLMICRO [ CML MICROCIRCUITS ]
