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A microprocessor controlled Morse keyer Here is a state-of-the-art Morse keyer which you can use to polish up your sending. It has a relay to control the keying of the transmitter & a loudspeaker so that you can listen to your sending. It also has a memory so that you can store a Morse message up to 64 characters long. Design by ALAEXANDRE ZATSEPIN It may seem like a contradiction in terms to have a “state-of-the-art” microprocessor controlled Morse keyer. After all, Morse code is the oldest method of sending messages over the air or along wires (telegraph) and many people probably think it is obsolete. However, without joining that debate and whether Morse should be used by amateur radio operators, this microprocessor controlled keyer is an elegant device to send your code. In fact, our photo shows it combined with an equally elegant Morse paddle; a highly desirable item to those who delight in CW (continuous wave) transmissions. Perhaps we should briefly mention that Morse code actually preceded radio transmissions by almost 50 years. Samual Morse patented his telegraph system in 1840 and it was not until 1898 that Guglielmo Marconi sent the first paid radiogram from the Isle of Wight. Even today, Morse code is used for radio messages and it is a method which can succeed in very difficult transmis­sion conditions where other more up-to-date methods fail. The Morse keyer is mounted on a small PC board which car­ries a Z8 microprocessor, a non-volatile mem­ ory chip, a miniature relay and not much else. The paddle is connected to a 4-way connector while the loudspeaker and relay output connections are made via 2-pin headers. A 2.1mm DC socket provides the power connection which can be to a 9V battery or to a 9V DC plugpack adaptor. Three buttons on the board control recording, speed and tone, while a August 1994  37 9x3.3k RESISTOR ARRAY P1 DOT 2 1 PADDLE +5V 1 430  3 4 5 6 7 2 8 9 15 16 3 DASH TONE S1 17 18 5 8 VCC P00 P22 P23 P02 5 D VIEWED FROM BELOW 12 100  Q1 VN0106 D G S 13 2 P25 3 P26 4 P27 QIN Q OUT P31 P32 P33 GND 7 X1 6 8 9 10 14 4MHz G O P01 IC1 Z86E08 11  K 4 D0 IC2 D1 3 93C46N SK 2 1 CS GND I LED1 STATUS P21 +5V PLAY S3 8 A VCC P20 1 P24 SPEED S2 G P3 S A K 100pF 9VDC INPUT P4 100pF RLY1 1 Q2 VN0106 D G S D1 1N4002 REG1 LM293-5 IN 100 16VW P2 2 GND OUT +5V 100 16VW MORSE KEYER Fig.1: the circuit is based on pre-programmed microcontroller IC1 (Z86E08) & non-volatile memory IC2. The non-volatile memory stores the message, tone, speed & cyclic redundancy code (CRC). setting is stored in the mem­ory buffer upon release of the key. LED indicates one of three possible states of the keyer. If power is applied and the LED is off, this indicates that the speed and tone settings are from the last operation and that there are no messages stored in the non-volatile memory. In this state, the keyer is in operating mode as described below. If the LED is on after power up, the speed and tone set­tings are from the last operation and there is a valid message in the memory. If the LED flashes after power up, the information in memory is invalid and is random. This condition may occur the first time the unit is powered up or if the non-volatile memory has been changed. To enter the operating mode, simply push the paddle key to the left or right; dot to the right and dash to the left, for example. The LED will stop flashing as soon as the key is operated and upon releasing the key, the circuit will enter the operating mode with a default speed of 70 characters per minute and a 1kHz tone (delivered via the loudspeaker). The relay operates in tandem with the loudspeaker. Record mode Sending speed To alter the sending speed, you press and hold down the SPEED button. To increase the speed, push the paddle 38  Silicon Chip key to the DOT position; to decrease the speed, push the paddle key to the DASH position. The Speed setting is stored in the non-volatile memory upon release of the key. To vary the tone from the loudspeaker, you press and hold down the TONE button and then push the paddle key to the DOT position to raise the frequency and to the DASH position to lower the frequency. Again, the Tone SPEAKER P3 Q1 BATTERY P3 100uF 100 100uF 1 D1 KEY P2 DOT 2x100pF Q2 PLAY S3 K Playback mode 430  X1 RELAY 1 REG1 IC1 Z86E08 1 GND SPEED S2 3.3k RES ARRAY 1 DASH IC2 936C46N TONE S1 The record mode allows you to store up to 64 characters in the memory. To enter the RECORD mode, press the SPEED and TONE buttons together. This will erase the existing message and the new message characters are loaded into the memory buffer. Pauses between characters are automatically set to one dash. Upon re­ ceiving 64 characters, the RECORD mode is terminated and after approximately 0.1 second, the keyer reverts to the normal operat­ing mode. To terminate the RECORD mode without entering all 64 characters, you press the PLAY button. After 0.1 second, the speaker will beep and the unit will revert to the normal operat­ing mode. After a message is stored, the LED will be on. A LED1 P1 Fig.2: install the parts on the PC board as shown here. Note particularly the orientation of the three switches. This is simple; just press the PLAY button. Any message in the buffer will start to play at the current speed and tone until the message is complete. To stop the message playback, you push the paddle key to either side. Circuit description The main element of the keyer is a Z86E08 microcontroller (IC1). This device incorporates a one-time programmable read-only memory (OTP ROM) PARTS LIST 1 PC board, 70 x 45mm 1 4MHz crystal (X1) 1 DIL relay (RLY1) 1 miniature 8-ohm loudspeaker 3 momentary contact PC-mount pushbutton switches 1 4-way PC mount male socket (P1) 2 2-pin headers and matching plugs (P2,P3) 1 2.1mm DC socket (P4) Semiconductors 1 Z86E08 programmed microcontroller (IC1) 1 93C46N non-volatile memory (IC2) 1 LM293-5 5V regulator (REG1) 2 VN0106 FETs (Q1, Q2) 1 green LED (LED1) 1 1N4002 rectifier diode (D1) which is loaded with the software. The Z86E08 has 14 input/output lines. Five are programmed as inputs (P20-P24), five are programmed as outputs (P26, P27, P00, P01 & P02) and one (P25) is programmed as bidirectional. Three of the input lines (P31, P32 & P33) are grounded. The internal oscillator of the micro­ controller runs at 4MHz, as set by the crystal connected to pins 6 & 7. A Capacitors 2 100µF 16VW electrolytic 2 100pF ceramic Resistors 1 9 x 3.3kΩ resistor array 1 430Ω 0.25W resistor 1 100Ω 0.25W resistor Kit availability A complete kit for the Morse Keyer is available from FLC Microdesign Pty Ltd, 28 Haugh­ton Rd, Oakleigh, Vic 3166. Phone (03)563 3096; Fax (03) 563 3017. Payment may be made by cheque or postal money order. Pricing is as follows: Complete kit (does not include DC plugpack) .....................$45.00 Optional DC plugpack ........$10.00 Postage & packing .............$10.00 9-way resistor network pulls all the inputs to +5V and when any of the buttons is pushed, the respective input is pulled to 0V. Of the three outputs, P00 drives the LED directly, P01 drives the loudspeaker via FET Q1, and P02 drives RLY1 via FET Q2. The non-volatile memory (IC2) (93C46N) has 1024 bits organ­ised as 64 x 16. It stores the message, tone, speed and cyclic redundancy code (CRC) in the absence of power. CRC is used for error detection, to prevent wrong messages, speeds or tones being accepted. Power is supplied via the DC input socket and then through the protective diode D1 to voltage regulator REG1 to provide the +5V supply rail. The total current consumption is less than 25mA with the optional relay. Assembly Construction of the Morse keyer is very straightforward since it is such a small board with few components. The PC board measures 70 x 45mm. Mount all the small components first, such as the diode, the voltage regulator, resistors, the two FETs and the capaci­tors. Make sure that these components are correctly polarised or oriented. This done, mount the two header sockets, the DC socket, the 4-way socket for the paddle keyer and the three button switches. Finally, you can mount the microcontroller (IC1), the memory chip (IC2) and the relay. After you have checked all your work carefully, you can apply power and check voltages on the board. The output of the 3-terminal regulator should be at +5V and this voltage should also be present at pin 5 of IC1 and pin 8 of IC2, as well as pin 1 of the resistor array. This being the case, connect a loudspeaker and a paddle and you can send SC Morse code. August 1994  39