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This application makes use of an SX Controller to build a Morse Code Keyer with the following features:
Accepts "Paddle-Type" or "Squeeze-Type" input devices
The schematic below shows the required external components:
If you are using an SX-Key Demo Board from Parallax, the required components are already in place.
To read the speed potentiometer, this application makes use of the bitstream ADC VP published by Ubicom and Parallax. The LED at RB6 is optional; it gives optical feedback as it is toggled according to the generated Morse code. RB6 is also used to drive an external circuit that keys the transmitter.
If connected to RB7, the piezo speaker provides an acoustic feedback. As most transmitters generate their own monitor tones, you might consider to not install the speaker. You may also add a switch to turn the speaker on or off.
RB0 is the "Dot" input, i.e. when this pin is pulled low, a short "Dot" signal will be generated, followed by a pause of the same length. As long as the line is held low, "Dots" and pauses will be repeated.
When RB1, the "Dash" input is pulled low, a "Dash" signal will be generated, that is three times longer than a "Dot". Again, a pause of one dot-length follows each "Dash". As long as the line is held low, "Dashes" and pauses will be repeated.
When you use a "Paddle-Type" input device, either the "Dot" or the "Dash" input can be low. If you use a "Squeeze-Type" device instead, either the "Dot", the "Dash", or both inputs can be low at a time. When both inputs are low, the "Dot" input has higher priority, i.e. "Dots" will be generated as long as it is low. When the line is released while the "Dash" line is still low, the system will continue sending "Dashes". If you pull the "Dot" line low, while the "Dash" line is low, "Dots" will be generated again.
If you press the "CQ" button, the CQ message, e.g. "cq cq cq de dk4tt dk4tt dk4tt" will be continuously sent and repeated.
When you press the "AR" button while the CQ message is being sent, this message will be completed, and then the AR message, e.g. "ar pse k" will be sent once, before the system enters into idle mode.
Pressing the "AR" button when the CQ message is not currently being sent, starts the transmission of one AR message before the system goes back to idle.
You can stop any automated message by pulling low the "Dot" or "Dash" lines. In this case, the message is interrupted after having completed the current character, the system sends a "Dot" or "Dash" (depending on what line went low), and returns to idle mode, i.e. it continues monitoring the RB3 0 input lines.
This is the program:
SX_KEY ifdef SX_KEY DEVICE SX28L, STACKX_OPTIONX, OSCXT5 FREQ 50_000_000 else DEVICE SX28AC, OSCHS, OPTIONX endif DEVICE TURBO RESET Start TRIS equ $0f LVL equ $0d PLP equ $0e Frequ equ 125 ; Beep frequency org $08 ; Global registers FsrSave ds 1 ; Storage for FSR Speed ds 1 ; Morse code speed State ds 1 ; ISR Morse handler state Flags ds 1 ; Flags to control the mainline ; program Ix ds 1 ; Message table index Count ds 1 ; Storage for "Morse Bitcount" Char ds 1 ; Storage for Morse character SendCq = Flags.0 ; State flags for mainline program SendAr = Flags.1 SendDot = Flags.2 SendDash = Flags.3 Tone = State.7 ; When this flag is set, a Dot or Dash ; is generated instead of a pause, ; and the speaker pin RB7 is toggled ; so generate a tone (Frequ deter- ; mines the tone frequency) org $10 ; Registers used by the ISR IsrVars = $ PortBBuff ds 1 ; Buffer for Port B data Beep ds 1 ; Beep timer for speaker output Length ds 1 ; Determines the length of the ; current signal or pause in ; multiples of a dot length SpeedTimer ds 1 ; This timer controls the length ; of a dot, i.e. the CPS of the ; Morse code BaseTimer ds 1 ; This is the basic timer used to ; divide down the ISR call frequency org $30 ; ADC registers ADC = $ AdcCount ds 1 ; Overflow counter AdcAcc ds 1 ; Accumulator PortCBuff ds 1 ; Buffer for Port C data org $000 ;-------------------------------------------------------------- ISR ; The Interrupt Service Routine ;-------------------------------------------------------------- mov FsrSave, FSR ; Save the original FSR for later ; restore ;------------------------------------------------------- ; ADC VP rc.1 = ADC in, rc.0 = charge/discharge ;------------------------------------------------------- bank ADC mov PortCBuff, rc and PortCBuff, #%11111100 ; Mask ADC pins mov w, >>rc not w and w, #%00000011 or PortCBuff, w sb PortCBuff.0 incsz AdcAcc inc AdcAcc dec AdcAcc mov w, AdcAcc inc AdcCount snz call PotAdjust ; Transform ADC value (0...255) ; into 32...160 snz mov Speed, w ; Save the transformed value snz clr AdcAcc mov rc, PortCBuff ; Set the ADC pins page ISR ; Reset the page (changed ; by PotAdjust) ;------------------------------------------------------- ; Morse code handler ;------------------------------------------------------- bank IsrVars ; If a button is down, set the associated flag for the ; mainline program. ; sb rb.0 ; Dot line setb SendDot sb rb.1 ; Dash line setb SendDash sb rb.2 ; CQ button setb SendCq sb rb.3 ; AR button setb SendAr ; Morse timer states ; Idle = 0 Pause1 = 1 Pause3 = 2 Pause5 = 3 Dot = 4 Dash = 5 Delay = 6 DelayS = Delay | $80 mov w, State ; Get the current state and w, #%01111111 ; and ignore bit 7 jmp pc+w jmp :ExitIsr jmp :InitPause1 jmp :InitPause3 jmp :InitPause5 jmp :InitDot jmp :InitDash jmp :Delay :InitPause1 ; Init for 1 dot-length pause mov Length, #1 jmp :EndInitP :InitPause3 mov Length, #2 ; Init for 3 dots-lengths pause. ; As a one dot-length pause is ; automatically appended to each ; dot and dash, the actual pause ; length is 2 dots here. jmp :EndInitP :InitPause5 mov Length, #4 ; Init for a 5 dots-lengths pause, ; (see above). :EndInitP mov SpeedTimer, Speed ; Initialize the speed timer mov State, #Delay ; Set next state jmp :ExitIsr :InitDot mov Length, #1 ; Setup for a dot jmp :EndInitD :InitDash mov Length, #3 ; Setup for a dash (3 dots-lengths) :EndInitD mov SpeedTimer, Speed ; Initialize the speed timer mov State, #DelayS ; Set next state jmp :ExitIsr :Delay ; Cause a delay decsz BaseTimer ; Decrement the base timer jmp :EndDelay decsz SpeedTimer ; Decrement the speed timer jmp :EndDelay mov SpeedTimer, Speed ; Re-initialize the speed timer decsz Length ; Decrement the length counter jmp :EndDelay sb Tone ; If a dot or dash is finished, jmp :EndPause mov State, #Pause1 ; automatically add a 1 dot-length jmp :EndDelay ; pause :EndPause mov State, #Idle ; When a pause has been finished, idle :EndDelay clrb PortBBuff.6 ; Prepare the LED bit sb Tone ; When the Tone flag is clear, jmp :ExitIsr ; no LED and no sound, else setb PortBBuff.6 ; turn LED on and decsz Beep ; decrement the Beep timer jmp :ExitIsr ; xor PortBBuff, #$80 ; Toggle the beeper pin mov Beep, #Frequ ; Re-initialize the Beep timer :ExitIsr mov rb, PortBBuff ; Set the port pins mov FSR, FsrSave ; Restore the FSR mov w, #-200 ; Call the ISR every 4 us retiw ;-------------------------------------------------------------- ; This routine reads the value indexed by w from Table. ; The table is used to transform the ADC values from 0 to 255 ; into a range from 32 to 160, and to provide a better pot ; resolution for higher speed values. ;-------------------------------------------------------------- PotAdjust page Table jmp w org $100 ;-------------------------------------------------------------- ; The mainline program ;-------------------------------------------------------------- Start ; Initialize the ports ; mode PLP mov !rb, #%11110000 ; Enable pull ups on port B inputs mode LVL ; Set cmos input levels mov !rc,#0 ; on port C inputs mode TRIS ; Setup inputs/outputs clr rc mov !rc,#%11111110 ; rc.1 = ADC in ; rc.0 = charge/discharge clr rb mov !rb, #%00111111 ; rb.7: beeper output, ; rb.6: LED output clr PortBBuff ; Clear some registers clr Flags clr State mov !option, #%10011111 ; Enable RTCC interrupt ; The bits in Flags are used to control the states of the main ; loop. :MainLoop snb SendDot ; When the dot contact is closed, go jmp :SendDot ; and send a dot (highest priority) snb SendDash ; When the dash contact is closed, jmp :SendDash ; go and send a dash test Flags ; If no flags are set at all, we are snz ; idle jmp :MainLoop mov w, #ArTab ; Prepare the address to send the ; "+ pse k" message sb SendAr ; If not SendAr, prepare the address mov w, #CqTab ; to send the "cq cq cq de..." ; message mov Ix, w ; Setup the message pointer snb SendAR ; If the user has pushed the AR ; button, while sending the ; "cq cq..." message, stop the CQ ; message after it is completed. clrb SendCQ :Loop mov w, Flags ; Get the flags and w, #%00001100 ; Mask the SendAr and SendCq flags sz ; If no flags are set, jmp :MainLoop ; don't send a message snb SendCQ ; While sending the "cq..." message, jmp :NoDebounce ; AR button pushes are accepted. snb SendAr ; While sending the "+ pse k" message, clr Flags ; no more AR button pushes are ; accepted. :NoDebounce mov m, #CqTab >> 8 ; Setup m:w for iread mov w, Ix iread ; Read the table item indexed by Ix mov Char, w ; Save the dash/dot pattern mov Count, m ; Save the dash/dot count test Count ; When Count = 0, we have either a snz ; pause, or an end of table. We jmp :TestEnd ; go to :TestEnd to find out. :Next ; Output a Morse character rl Char ; Next bit -> c mov w, #Dash ; Prepare for a dash sc ; If c is set, it is a dash, mov w, #Dot ; else a dot mov State, w ; Setup the state :Send test State ; Wait until the ISR has sent the sz ; dash or dot jmp :Send dec Count ; Decrement the dash/dot count sz ; If there are more dashes/dots to be jmp :Next ; sent, loop back mov State, #Pause3 ; Generate a 3 dots-length pause :Pause test State ; Wait until the ISR has generated sz ; the pause jmp :Pause inc Ix ; Next character in the message table jmp :Loop :TestEnd ; When a table item has a Count of 0, test Char ; it is either a Pause5 (Char != 0), snz ; or the end of the table (Char == 0) jmp :MainLoop mov State, #Pause5 ; Setup state for Pause5 jmp :Pause ; Go and wait until the pause is done :SendDot mov State, #Dot ; Send a dot when the user has pressed jmp :WaitSend ; the dot button :SendDash mov State, #Dash ; Send a dash when the use has pressed ; the dash button :WaitSend ; Wait until the ISR has sent the test State ; dash or the dot sz jmp :WaitSend clr Flags ; Clear the flags in order to stop jmp :MainLoop ; any message being currently sent. org $200 ; The message tables ; ; The first four bits in each item specify the number of ; dashes and dots. The next eight bits specify from "left ; to right" the dashes (1) and dots (0). ; ; A value of $001 specifies a 5 dot-lengths pause, and ; a value of $000 specifies the end of a message. ; CqTab dw $001 ; Pause 5 dw $400 + %10100000 ; C dw $400 + %11010000 ; Q dw $001 ; Pause 5 dw $400 + %10100000 ; C dw $400 + %11010000 ; Q dw $001 ; Pause 5 dw $400 + %10100000 ; C dw $400 + %11010000 ; Q dw $001 ; Pause 5 dw $300 + %10000000 ; D dw $100 + %00000000 ; E dw $001 ; Pause 5 dw $300 + %10000000 ; D dw $300 + %10100000 ; K dw $500 + %00001000 ; 4 dw $100 + %10000000 ; T dw $100 + %10000000 ; T dw $001 ; Pause 5 dw $300 + %10000000 ; D dw $300 + %10100000 ; K dw $500 + %00001000 ; 4 dw $100 + %10000000 ; T dw $100 + %10000000 ; T dw $001 ; Pause 5 dw $300 + %10000000 ; D dw $300 + %10100000 ; K dw $500 + %00001000 ; 4 dw $100 + %10000000 ; T dw $100 + %10000000 ; T dw $001 ; Pause 5 dw $000 ; End ArTab dw $001 ; Pause 5 dw $500 + %01010000 ; AR dw $001 ; Pause 5 dw $400 + %01100000 ; P dw $300 + %00000000 ; S dw $100 + %00000000 ; E dw $001 ; Pause 5 dw $300 + %10100000 ; K dw $000 ; End org $400 Table retw 32, 32, 32, 32 retw 33, 33, 33, 33 retw 34, 34, 34, 34 retw 35, 35, 35, 35 retw 36, 36, 36, 36 retw 37, 37, 37, 37 retw 38, 38, 38 retw 39, 39, 39 retw 40, 40, 40 retw 41, 41, 41 retw 42, 42, 42 retw 43, 43, 43 retw 44, 44, 44 retw 45, 45, 45 retw 46, 46, 46 retw 47, 47, 47 retw 48, 48, 48 retw 49, 49, 49 retw 50, 50 retw 51, 51 retw 52, 52 retw 53, 53 retw 54, 54 retw 55, 55 retw 56, 56 retw 57, 57 retw 58, 58 retw 59, 59 retw 60, 60 retw 61, 61 retw 62, 62 retw 63, 63 retw 64, 64 retw 65, 65 retw 66, 66 retw 67, 67 retw 68, 68 retw 69, 69 retw 70, 70 retw 71, 71 retw 72, 72 retw 73, 73 retw 74, 74 retw 75, 75 retw 76, 76 retw 77, 77 retw 78, 78 retw 79, 79 retw 80, 80 retw 81, 81 retw 82, 82 retw 83, 83 retw 84, 84 retw 85, 85 retw 86, 86 retw 87, 87 retw 88, 88 retw 89, 89 retw 90, 90 retw 91, 91 retw 92, 92 retw 93, 93 retw 94, 94 retw 95, 95 retw 96 retw 97, 97 retw 98, 98 retw 99, 99 retw 100, 100 retw 101, 101 retw 102, 102 retw 103, 103 retw 104, 104 retw 105, 105 retw 106, 106 retw 107, 107 retw 108, 108 retw 109, 109 retw 110, 110 retw 111, 111 retw 112, 112 retw 113, 113 retw 114, 114 retw 115, 115 retw 116, 116 retw 117, 117 retw 118, 118 retw 119, 119 retw 120, 120 retw 121, 121 retw 122, 122 retw 123, 123 retw 124, 124 retw 125, 125 retw 126, 126 retw 127, 127 retw 128, 128 retw 129, 129 retw 130, 130 retw 131, 131 retw 132, 132 retw 133, 133 retw 134, 134 retw 135, 135 retw 136 retw 137 retw 138 retw 139 retw 140 retw 141 retw 142 retw 143 retw 144 retw 145 retw 146 retw 147 retw 148 retw 149 retw 150 retw 151 retw 152 retw 153 retw 154 retw 155 retw 156 retw 157 retw 158 retw 159 retw 160
In this application, the mainline program initializes the ports and some registers, and then enters into a loop that handles sending pre-defined messages. It also handles the button-down and Morse-key device events but it does not read the associated input lines. Instead, it evaluates the states of the flags eventually set by the ISR which actually reads the input lines.
The ISR runs the ADC VP that is used to read the current setting of the speed potentiometer. The ISR also polls the input lines at Port B, and takes care of the necessary timing to generate "Dots", "Dashes", pauses, and the audio signal for the piezo speaker.
The timer part of the ISR is designed as a state engine. Depending on the value of the State variable, various parts of the ISR code are executed.
As pauses, "Dots", and "Dashes" also require a time delay with the only difference that "Dots" and "Dashes" must control the output signal, and also must generate the audio signal for the speaker, bit Status.7 has a special meaning. If this bit is set, "Dots" or "Dashes" are sent, i.e. the speaker and output lines will be activated in this case.
The two pre-defined messages (the CQ and the AR message) are stored in program memory. The program uses the iread instruction to read items from those tables.
As Morse code characters have variable lengths, the first four bits of a table entry are used to specify the total number of "Dots" and "Dashes" for each character. The remaining eight bits contain the Morse code pattern. Each "Dot" is represented by a 0-bit, and each "Dash" is represented by a 1-bit. The "Dash" and "Dot" codes are arranged from "left" to "right", i.e. the first code element is located at bit 7, the second one at bit 6, etc. When a Morse character has less than eight "Dashes" and "Dots", the remaining lower bits are cleared.
To either indicate a pause of five dot-lengths or the end of a message, the upper four bits of a table entry are cleared. When the lower eight bits are also cleared, this means that the end of the table has been reached. If the lower eight bits contain %00000001, a pause of five dot-lengths will be generated instead.
The ADC VP used here, returns a result from 0 through 255 for an input voltage between 0 and 5 V. Using this full range to setup the Speed timer would result in extremely high and low Morse speeds when the potentiometer is turned to its two end-positions. In addition, when you use a linear potentiometer, the speed variation is very sensitive at higher speeds. Therefore, we use a table in order to convert the ADC value (0 255) into a range from 32 through 160 and to "flatten" the potentiometer curve at higher speed values.
file: /Techref/scenix/lib/io/osi2/Morse.htm, 20KB, , updated: 2003/4/12 19:23, local time: 2024/8/14 15:48,
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