Quadrature encoder obex - mod
jeromelab
Posts: 31
Hello,
I am using the Jeff Martin's quadrature object which works fine with the avago HEDR-54xx encoders. Now I am hooking up 5 encoders to the same board and folloowing layout and cabling issues I would prefer having the 5 encoders not being assigned to successive pins (0-1 for fisrt encoder then 2-3 for the next ...) but every 5 pins(0-1 for first, 5-6 for second ...).
I have no experience with propeller assembly. So how would I modify the object so that I can have the 5 pins layout (or even better having a variable to parametrize this increment). I understand there is probably a simple increment somewhere but rather than trying to locate it by hit and miss, I thought I will ask first people who knows...
In attachment, Jeff Martin's object.
Thanks
I am using the Jeff Martin's quadrature object which works fine with the avago HEDR-54xx encoders. Now I am hooking up 5 encoders to the same board and folloowing layout and cabling issues I would prefer having the 5 encoders not being assigned to successive pins (0-1 for fisrt encoder then 2-3 for the next ...) but every 5 pins(0-1 for first, 5-6 for second ...).
I have no experience with propeller assembly. So how would I modify the object so that I can have the 5 pins layout (or even better having a variable to parametrize this increment). I understand there is probably a simple increment somewhere but rather than trying to locate it by hit and miss, I thought I will ask first people who knows...
In attachment, Jeff Martin's object.
Thanks
Comments
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 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 bufferI did not have time to thoroughly analyze the code so it may require other changes as well.
Seems it needs more work than modifying the "ror".
Nevermind I found another (hardware) solution.