Summary

The Microchip data modem library is composed of ITU-T compliant algorithms for V.21, V.22, V.22bis, V.23, V.32 and V.32bis modem recommendations. Bell standard 103 is also included in this library.
V.21, V.23 and Bell 103 are Frequency Shift Keying (FSK) modems. V.32, V.32bis and V.22bis are Quadrature Amplitude Modulated (QAM) modems.
V.22 is a Quadrature Phase Shift Keyed (QPSK) modem. V.21, V.22, V.22bis, V.32 and V.32bis are all 2-wire, Full Duplex modems. V.23 is Full-Duplex when it operates with a 75 bps backwards channel.
V.22bis includes fallback to V.22, V.23 and V.21 standards. V.32bis include fallback to V.22bis, V.22, V.23 and V.21 standards.

Typical Applications

The dsPIC Soft Modem is well suited for small transaction orientated based applications such as, but not limited to:

Contents

The data modem library is provided in two basic software packages:

The library currently supports single channel data-pump implementations.
Both libraries are supported with fallback data pump modulations down to V.21. Each data modem library is provided with a respective library archive containing all the data pump object code modules required to link to the user's application. Hardware component drivers, such as UART and data converter interface for DAA/AFE I/O are provided in assembly source code for linking with the user's application.

ITU-T Recommendation V.42 is provided with each library. V.42 contains a High Level Data Link Control (HDLC) protocol referred to as Link Access Procedure for Modems (LAPM) and defines error correcting protocols for modems.
All data pump modulations are developed in ASM30 assembly code yielding optimal code size and execution time. The AT, V.42 and Data Pump APIs are based on C30 C language.
Electronic documentation accompanies the modem library to help you become familiar with and implement the library functions. A comprehensive Soft Modem User's Guide describes the required APIs for the AT, V.42 and data Ppump layers.

Features and Performance of Data Modems

Notes:

1. Data pump modules, V.21, V.22, V.22bis, V.23, V.32, V.32bis and Bell 103 are implemented in Assembly language. V.42, Data Pump and AT Command APIs are implemented in C language.
2. The program/data memory usage for the V-series data pumps is NOT cumulative, due to the sharing of components internally.
3. Memory size does not account for application which combines data pump, V.42 and AT commands (if required).
4. V.21/Bell 103 and V.23 data pumps do not require V.42.

Technical Notes

V.21 operates at 300 symbols per second, at mean frequencies of 1080+/-100 Hz and 1750+/-100 Hz. V.23 operates at mean frequencies of 1500+/-200 Hz for the 600bps forward channel and 1700+/-400 Hz for the 1200 bps forward channel. The V.23, 75 bps, backwards channel has a mean frequency of 420+/-30 Hz.

V.32 and V.32bis data modems operate at 2400 symbols per second on a carrier frequency of 1800 Hz, in both directions. Both V.32 and V.32bis implement trellis coding modulation (TCM) for all data rates, except 4800 bps. V.32 also includes uncoded 9600 bps.

Part Numbers and Ordering Information

Note: Quantities are per project, payable as a one-time license fee based on estimated lifetime volume for products resulting from the project. Please consult the factory for quantities above 100K.