Im Eulenflug 25
D-51399 Burscheid, Germany
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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.
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