K20 Serial Interface Guide
Contents
1. K1EL CW Keyer and Keyboard Serial Interface Guide K 20 Introduction The K20 is a single board Morse keyer with a built in IBM AT keyboard interface It can be used as a keyer only or as a CW keyboard This document will describe how to interface to the asynchronous serial port of the keyer and drive it from a personal computer or other host The interface is based on a simple set of ASCII commands The K20 provides a single handshake line that tells when it is ready to accept data Command Set The K20 only accepts asynchronous serial data at 1200 baud The format must be 8 data bits 1 stop bit with no parity Note that the K20 must be modified to accept RS232 data see the K20 hardware modification section for details Normal alphanumeric characters will be sent as Morse letters commands are control characters which are listed below Special characters such as prosigns are listed in a separate table When formatting a command no spaces should be added between commands and or arguments also numeric values must always be sent as two decimal digits with a leading zero if the value is less than 10 The only exceptions to this are the MODE register command in which the value is sent as a two digit hexadecimal value Immediate Commands A lt nn gt Olh on Set sidetone frequency to nn where nn 4 OAH see table below B lt nn gt 02h nn Set keying speed to nn WPM where nn 05 99 C lt nn gt 03h nn Set Dit Dah Ratio to nn 10 nn2. 05 32 D lt nn gt 04h nn Set PTT Lead In delay to nn 10 milliseconds nn 00 99 E lt nn gt 05h nn Set PTT Tail delay to nn 10 milliseconds nn 00 99 F 06h Pause transmit On Off G lt nn gt 07h nn Flow Control Count 01 30 change not recommended H 08h Backspace buffer input pointer SI 09h Say Status J OAh Clear circular buffer and abort current process K OBh Key Down on off L lt nn gt OCh nn Set HSCW speed to nn 100 LPM M lt nn gt ODh nn Set Extraspace to nn 10 nn 05 32 N lt hh gt OEh h Set Mode Register to hex value hh see Mode Reg Description o lt list gt OFh lt gt Load Keyer Default List see Defaults Description P lt nn gt 10h nn First bit extension to nn milliseconds nn 0 99 Q lt nn gt 11h nn Set Weighting Adjustment in milliseconds nn 0 99 50 00 R lt nn gt 12h nn Adjust swing sensitivity nn 0 99 S lt tl gt 13h tl Start Practice t e r 1 2 3 4 see K20 User Guide Buffered Message Commands AV 16h PTT on off W 17h Key on off AX 18h nn Wait for nn seconds nn 0 99 y lt xy gt 19h xy Merge letters x y z lt nn gt 1Ah nn Change WPM speed to nn WPM nn 5 99 AN 1Ch Analog diagnostic lt nn gt 1Dh nn Set HSCW speed to nn a lt nn gt 1Eh nn Set loop timer to nn nn 0 99 Special Characters eN BT BT QSL DN gt SK DEL 8 dits KN AS AR QRZ K20 Serial Interface Guide 10 10 00 Page 1 K1EL K20 CW Keyer and Keyboard S
3. anual 10 10 00 Page 2 K1EL K20 CW Keyer and Keyboard Console remove Transmit Flow Control Serial Data Output to Host Input to K20 Connections to K20 For External Serial Data Control If the host provides true RS232 formatted signals a level converter MUST be installed between the host and the K20 or damage will result Standard RS232 levels transit between 12 and 12 volts DC while the K20 expects 0 to 5 volts There are several RS232 level converters available from Maxim that supply all the interface details in one package Typical ones to look at are the MAX232 and the MAX203 Following is a diagram of a typical application using the MAX 232 MAX232 From K20 Flow To RS232 CTS Input Control Output From RS232 To K20 Receive Transmit Output Input RS232 Level Translator K 20 User s Manual 10 10 00 Page 3
4. idetone Values Value Frequency Mode Register Description There is an eight bit byte in the Keyer PIC that contains bit flags that control the operation modes of the keyer Each bit s state controls a particular mode following is a table showing the bit functions Bit Function Power Up State lambic A when 1 lambic B 0 Farnsworth on when 1 Bug Mode on when Defaults Description All of the Keyers internal state registers can be initialized in one block transfer This feature is useful for fast initialization or for changing the whole configuration of the keyer quickly The following illustrates how the command is issued and the order of control words loaded Mode Register Value WPM Speed Sidetone Value 8 9 CT ExtraSpace 10 Sample Adjust Hardware Modification The K20 was originally designed to have the Console PIC provide the serial input to the Keyer PIC To operate the K20 with an external serial data source the Console PIC must be removed from its socket and wires are soldered to two unused hole positions on the K20 PCB One wire is for serial data to the K20 the other is a flow control ready output These signals are connected to a host which provides all control to the K20 The paddle inputs to the Keyer PIC are unaffected and work normally The host must monitor the flow control line if it is high the host must wait till the K20 drops it before sending any additional bytes K 20 User s M
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