Detect movment in an encoder
Landry
Posts: 17
hey,
I'm using the the Quadrature encoder object made By Jeff martin and would like to set the pin high when the first movement from the encoder is detected (pulse).
I added a comparison in the existing code but it seems like it is not in the right place.
According the truth table I though that the highlighted code is at the right place but unfortunately, might is set to high anyway.
Can anybody help me with this.
Thanks.
I'm using the the Quadrature encoder object made By Jeff martin and would like to set the pin high when the first movement from the encoder is detected (pulse).
I added a comparison in the existing code but it seems like it is not in the right place.
DAT
'Read all encoders and update encoder positions in main memory.
'See "Theory of Operation," below, for operational explanation.
'Cycle Calculation Equation:
' Terms: SU = :Sample to :Update. UTI = :UpdatePos through :IPos. MMW = Main Memory Write.
' AMMN = After MMW to :Next. NU = :Next to :UpdatePos. SH = Resync to Hub. NS = :Next to :Sample.
' Equation: SU + UTI + MMW + (AMMN + NU + UTI + SH + MMW) * (TotEnc-1) + AMMN + NS
' = 92 + 16 + 8 + ( 16 + 4 + 16 + 6 + 8 ) * (TotEnc-1) + 16 + 12
' = 144 + 50*(TotEnc-1)
org 0
Update test Pin, #$20 wc 'Test for upper or lower port
muxc :PinSrc, #%1 'Adjust :PinSrc instruction for proper port
mov IPosAddr, #IntPos 'Clear all internal encoder position values
movd :IClear, IPosAddr ' set starting internal pointer
mov Idx, TotEnc ' for all encoders...
:IClear mov 0, #0 ' clear internal memory
add IPosAddr, #1 ' increment pointer
movd :IClear, IPosAddr
djnz Idx, #:IClear ' loop for each encoder
mov St2, ina 'Take first sample of encoder pins
shr St2, Pin
:Sample mov IPosAddr, #IntPos 'Reset encoder position buffer addresses
movd :IPos+0, IPosAddr
movd :IPos+1, IPosAddr
mov MPosAddr, PAR
mov St1, St2 'Calc 2-bit signed offsets (St1 = B1:A1)
mov T1, St2 ' T1 = B1:A1
shl T1, #1 ' T1 = A1:x
:PinSrc mov St2, inb ' Sample encoders (St2 = B2:A2 left shifted by first encoder offset)
shr St2, Pin ' Adj for first encoder (St2 = B2:A2)
xor St1, St2 ' St1 = B1^B2:A1^A2
xor T1, St2 ' T1 = A1^B2:x
and T1, BMask ' T1 = A1^B2:0
or T1, AMask ' T1 = A1^B2:1
mov T2, St1 ' T2 = B1^B2:A1^A2
and T2, AMask ' T2 = 0:A1^A2
and St1, BMask ' St1 = B1^B2:0
shr St1, #1 ' St1 = 0:B1^B2
xor T2, St1 ' T2 = 0:A1^A2^B1^B2
mov St1, T2 ' St1 = 0:A1^B2^B1^A2
shl St1, #1 ' St1 = A1^B2^B1^A2:0
or St1, T2 ' St1 = A1^B2^B1^A2:A1^B2^B1^A2
and St1, T1 ' St1 = A1^B2^B1^A2&A1^B2:A1^B2^B1^A2
[b][color=purple]mov $1F6, #$80
cmp St1, 0 wz
if_nz mov $1F4, #$80
[/color][/b] mov Idx, TotEnc 'For all encoders...
:UpdatePos ror St1, #2 'Rotate current bit pair into 31:30
mov Diff, St1 'Convert 2-bit signed to 32-bit signed Diff
sar Diff, #30
:IPos add 0, Diff 'Add to encoder position value
wrlong 0, MPosAddr 'Write new position to main memory
add IPosAddr, #1 'Increment encoder position addresses
movd :IPos+0, IPosAddr
movd :IPos+1, IPosAddr
add MPosAddr, #4
:Next djnz Idx, #:UpdatePos 'Loop for each encoder
jmp #:Sample 'Loop forever
'Define Encoder Reading Cog's constants/variables
AMask long $55555555 'A bit mask
BMask long $AAAAAAAA 'B bit mask
MSB long $80000000 'MSB mask for current bit pair
Pin long 0 'First pin connected to first encoder
TotEnc long 0 'Total number of encoders
Idx res 1 'Encoder index
St1 res 1 'Previous state
St2 res 1 'Current state
T1 res 1 'Temp 1
T2 res 1 'Temp 2
Diff res 1 'Difference, ie: -1, 0 or +1
IPosAddr res 1 'Address of current encoder position counter (Internal Memory)
MPosAddr res 1 'Address of current encoder position counter (Main Memory)
IntPos res 16 'Internal encoder position counter buffer
''
''
''**************************
''* FUNCTIONAL DESCRIPTION *
''**************************
''
''Reads 1 to 16 two-bit gray-code quadrature encoders and provides 32-bit absolute position values for each and optionally provides delta position support
''(value since last read) for up to 16 encoders. See "Required Cycles and Maximum RPM" below for speed boundary calculations.
''
''Connect each encoder to two contiguous I/O pins (multiple encoders must be connected to a contiguous block of pins). If delta position support is
''required, those encoders must be at the start of the group, followed by any encoders not requiring delta position support.
''
''To use this object:
'' 1) Create a position buffer (array of longs). The position buffer MUST contain NumEnc + NumDelta longs. The first NumEnc longs of the position buffer
'' will always contain read-only, absolute positions for the respective encoders. The remaining NumDelta longs of the position buffer will be "last
'' absolute read" storage for providing delta position support (if used) and should be ignored (use ReadDelta() method instead).
'' 2) Call Start() passing in the starting pin number, number of encoders, number needing delta support and the address of the position buffer. Start() will
'' configure and start an encoder reader in a separate cog; which runs continuously until Stop is called.
'' 3) Read position buffer (first NumEnc values) to obtain an absolute 32-bit position value for each encoder. Each long (32-bit position counter) within
'' the position buffer is updated automatically by the encoder reader cog.
'' 4) For any encoders requiring delta position support, call ReadDelta(); you must have first sized the position buffer and configured Start() appropriately
'' for this feature.
''
''Example Code:
''
''OBJ
'' Encoder : "Quadrature Encoder"
''
''VAR
'' long Pos[noparse][[/noparse]3] 'Create buffer for two encoders (plus room for delta position support of 1st encoder)
''
''PUB Init
'' Encoder.Start(8, 2, 1, @Pos) 'Start continuous two-encoder reader (encoders connected to pins 8 - 11)
''
''PUB Main
'' repeat
'' <read Pos[noparse][[/noparse]0] or Pos[noparse][[/noparse]1] here> 'Read each encoder's absolute position
'' <variable> := Encoder.ReadDelta(0) 'Read 1st encoder's delta position (value since last read)
''
''________________________________
''REQUIRED CYCLES AND MAXIMUM RPM:
''
''Encoder Reading Cog requires 144 + 50*(TotEnc-1) cycles per sample. That is: 144 for 1 encoder, 194 for 2 encoders, 894 for 16 encoders.
''
''Conservative Maximum RPM of Highest Resolution Encoder = XINFreq * PLLMultiplier / EncReaderCogCycles / 2 / MaxEncPulsesPerRevolution * 60
''
''Example 1: Using a 4 MHz crystal, 8x internal multiplier, 16 encoders where the highest resolution encoders is 1024 pulses per revolution:
'' Max RPM = 4,000,000 * 8 / 894 / 2 / 1024 * 60 = 1,048 RPM
''
''Example 2: Using same example above, but with only 2 encoders of 128 pulses per revolution:
'' Max RPM = 4,000,000 * 8 / 194 / 2 / 128 * 60 = 38,659 RPM
'____________________
'THEORY OF OPERATION:
'Column 1 of the following truth table illustrates 2-bit, gray code quadrature encoder output (encoder pins A and B) and their possible transitions (assuming
'we're sampling fast enough). A1 is the previous value of pin A, A2 is the current value of pin A, etc. '->' means 'transition to'. The four double-step
'transition possibilities are not shown here because we won't ever see them if we're sampling fast enough and, secondly, it is impossible to tell direction
'if a transition is missed anyway.
'
'Column 2 shows each of the 2-bit results of cross XOR'ing the bits in the previous and current values. Because of the encoder's gray code output, when
'there is an actual transition, A1^B2 (msb of column 2) yields the direction (0 = clockwise, 1 = counter-clockwise). When A1^B2 is paired with B1^A2, the
'resulting 2-bit value gives more transition detail (00 or 11 if no transition, 01 if clockwise, 10 if counter-clockwise).
'
'Columns 3 and 4 show the results of further XORs and one AND operation. The result is a convenient set of 2-bit signed values: 0 if no transition, +1 if
'clockwise, and -1 and if counter-clockwise.
'
'This object's Update routine performs the sampling (column 1) and logical operations (colum 3) of up to 16 2-bit pairs in one operation, then adds the
'resulting offset (-1, 0 or +1) to each position counter, iteratively.
'
' 1 | 2 | 3 | 4 | 5
'-------------|-------------|----------------------|----------------|-----------
' | | A1^B2^B1^A2&(A1^B2): | 2-bit sign |
'B1A1 -> B2A2 | A1^B2:B1^A2 | A1^B2^B1^A2 | extended value | Diagnosis
'-------------|-------------|----------------------|----------------|-----------
' 00 -> 00 | 00 | 00 | +0 | No
' 01 -> 01 | 11 | 00 | +0 | Movement
' 11 -> 11 | 00 | 00 | +0 |
' 10 -> 10 | 11 | 00 | +0 |
'-------------|-------------|----------------------|----------------|-----------
' 00 -> 01 | 01 | 01 | +1 | Clockwise
' 01 -> 11 | 01 | 01 | +1 |
' 11 -> 10 | 01 | 01 | +1 |
' 10 -> 00 | 01 | 01 | +1 |
'-------------|-------------|----------------------|----------------|-----------
' 00 -> 10 | 10 | 11 | -1 | Counter-
' 10 -> 11 | 10 | 11 | -1 | Clockwise
' 11 -> 01 | 10 | 11 | -1 |
' 01 -> 00 | 10 | 11 | -1 |
According the truth table I though that the highlighted code is at the right place but unfortunately, might is set to high anyway.
Can anybody help me with this.
Thanks.
Comments
Also, you should use the names for DIRA and OUTA. It just makes it easier to read.
[color=red]CON _CLKMODE = XTAL1 + PLL16X _XINFREQ = 5_000_000[/color] [color=red] ZERO = 48 NINE = 57[/color] [color=red] MAX_LENGTH = 400 DELIMITER = 13[/color] [color=red] PLUS = "+" MINUS = "-" PIN_ENCODER_BOX_A = 3 PIN_ENCODER_BOX_B = 4 'PIN_ENCODER_BOX_I = 5 PIN_ENCODER_PP_A = 5 PIN_ENCODER_PP_B = 6 'PIN_ENCODER_PP_I = 8[/color] [color=orange]OBJ _Numbers : "Numbers" _Keyboard : "Keyboard" _Encoders : "Quadrature Encoder" '_TV : "PC_Text" _TV : "VGA_Text" _BS2 : "BS2_Functions"[/color] [color=green]VAR byte _dataIn[noparse][[/noparse]4] long _position[noparse][[/noparse]2][/color] [color=blue]PUB Main | triggerPosition, invalid, triggerSign[/color] [color=blue] _TV.start(16) _TV.str(string("Position calculator...",13))[/color] [color=blue] _BS2.start(31, 30) _Keyboard.start(26, 27)[/color] [color=blue] 'Trigger position chosen by the user invalid := true _TV.str(string("Trigger position:")) repeat while invalid Readinput(@_dataIn, 3) triggerPosition := _Numbers.FromStr(@_dataIn, 10) _TV.out(13)[/color] [color=blue] if triggerPosition => ZERO and triggerPosition =< MAX_LENGTH invalid := false[/color] [color=blue] 'Trigger sign chosen by the user invalid := true _TV.str(string("Sign:")) repeat while invalid ReadInput(@_datain, 1) _TV.out(13) if strcomp(_dataIn, PLUS) 'triggerSign := _dataIn[noparse][[/noparse]0] triggerPosition := 1 * triggerPosition invalid := false if strcomp(_dataIn, MINUS) triggerPosition := -1 * triggerPosition invalid := false 'Encoder _Encoders.start(PIN_ENCODER_BOX_A, 1, 0, @_position) repeat _TV.dec(_position[noparse][[/noparse]0]) if _position[noparse][[/noparse]0] > 1 _BS2.PULSOUT_us(PIN_ENCODER_BOX_A, 500) 'send quit _TV.out(13)[/color] [color=purple]PRI ReadInput(inputPtr, length) | value, ptr {{ Accepts a string of characters - up to 3 - to be passed by reference String acceptance terminates with a carriage return or the defined delimiter character. Will accept up to 3 characters before passing back. }} ptr:=0[/color] [color=purple] bytefill(@_dataIn, 0, length) value := 0 repeat while (value <> Delimiter) and (ptr < length) value := _Keyboard.getkey _dataIn[noparse][[/noparse]ptr] := value ptr++ _TV.out(value)[/color] [color=purple] _dataIn[noparse][[/noparse]ptr]:=0 [/color] [color=purple] byteMove(inputPtr, @_dataIn, (length + 1))[/color]·I don't think that i'm ussing pin 7 anywhere in here or I'm and didn't know about it.