The first thing that comes to mind is to decode the
dot dash dash dot into 0110 with a '1' representing
dash and a '0' representing the dot. Then store a
table in the PIC and do a simple compare through
the table until a match is found. The only problem
I see with this method is trying to tell the difference
between a J ( . - - - ) and a 2 ( . . - - - ) which would be
0111 and 00111 respectively.

Maybe this gives you some other ideas.

Regards

Gavin
--------------------------
vulcan@ihug.co.nz
ICQ# 18675389
http://www.geocities.com/TheTropics/Cabana/2625
--------------------------

Sent:   Wednesday, 04, November, 1998 01:08 PM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        Re: Morse Decoder

Life is sometimes curious. Last weekend I spent most of the
weekend designing a protoboard and software to use as a base for -
 yes you've guessed it a Morse Decoder! The stripboard prototype
has a 4*20 LCD (cos I got one very cheap) driven by a 74164 and 3
16F84 pins and a 24LC65 using 2 more of the pins. All the 3 wire-
LCD software works OK and all the I2C to the 24LC65 now works.

Basic idea is to detect interrupt on PORTB and try to figure out
dot, dash (or space equivalents) and then use the 24LC65 to hold
both menu options and a sparse lookup table for the Morse. That
way pretty much all the PIC processing can go into figuring out
dot/dash.

I had planned initially just to attach a key to PORTB for testing -
then play around with an electret mike passing thru some
bandpass filter to a 567 tone decoder - but since my electronic
skills are very poor I might need some help here!

Anyone worked on any morse decoding algorithms wants to share
ideas then fine - pls let me know - probably best to my reader
direct and if there is  interest I'll summarize here later

Brian
Brian Jones
Technical Planner
Java Technology Centre
IBM Hursley