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ELE22MIC Lecture 14 & 15

ELE22MIC Lecture 14 & 15. Edge Detector Latch vs Flip Flop S-R Latch, Transparent D-Latch Clocked D-Latch J-K Flip Flop, Toggle Flip Flop Flip Flop Applications Register/Memory, Shift Register, Counter 68HC11 Analog to Digital Converter Variable Speed Stepper Motor Application.

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ELE22MIC Lecture 14 & 15

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  1. ELE22MIC Lecture 14 & 15 • Edge Detector • Latch vs Flip Flop • S-R Latch, Transparent D-Latch • Clocked D-Latch • J-K Flip Flop, Toggle Flip Flop • Flip Flop Applications • Register/Memory, Shift Register, Counter • 68HC11 Analog to Digital Converter • Variable Speed Stepper Motor Application

  2. 68HC11 Timer - PreScaler • Crystal Frequency vs clock Pre-Scaler

  3. Edge Detection Positive-Going Edge Detection

  4. Clocked Set Reset Latch

  5. Transparent D Latch

  6. Edge Triggered D Flip Flop Positive Clock Edge-Triggered D Flip Flop

  7. J-K Flip Flop

  8. Toggle Flip Flop While the toggle pin is held high, the Q line changes state on every positive CLK transition.

  9. 4 Bit - Ripple Counter

  10. Timer-Counter Pre-Scaler

  11. 3 Bit Shift Register

  12. Variable Speed Stepper Motor • The next application we will look at is a Variable Speed Stepper Motor control • The forward/reverse speed is controlled by a potentiometer connected to the ADC input

  13. Variable Speed Stepper Motor • The unsigned potentiometer value is biased by 128 so that mid-way = 0 speed, 255 = full speed forwards, -255 = full speed reverse. • The stepper motor coil activation sequence is controlled by four output lines of Port A

  14. ULN2003

  15. Stepper Motor

  16. ULN2003

  17. Variable Speed Stepper Motor (1) REGBAS EQU $1000 Starting address for register block RAM EQU $2000 PORTA EQU $00 Port A INPUT:PA0..2, OUTPUT:PA3..6, & I/O PA7 * Port Outputs can be used when not using timer * latches specified in TCTL1 (below) PORTB EQU $04 Output port B CFORC EQU $0B Force Output Compare... OC1M EQU $0C OClM7,OClM6,OClM5,OClM4;OClM3,-,-,- OC1D EQU $0D OClD7,OClD6,OClD5,OClD4;OClD3,-,-,- TCNT EQU $0E Free running counter (16 bit) TIC1 EQU $10 IC1 register (16 bit) TOC1 EQU $16 OC1 register (16 bit) TOC2 EQU $18 OC2 register (16 bit) TOC3 EQU $1A OC3 register (16 bit)

  18. Variable Speed Stepper Motor (2) TCTL1 EQU $20 OM2,OL2,OM3,OL3;OM4,OL4,OM5,OL5 TCTL2 EQU $21 -,-,EDGlB,EDGlA;EDG2B,EDG2A,EDG3B,EDG3A TMSK1 EQU $22 OC1I,OC2I,OC3I,OC4I;OC51,IC1I,IC2I,IC3I TFLG1 EQU $23 OC1F,OC2F,OC3F,OC4F;OC5F,IC1F,IC2F,IC3F TMSK2 EQU $24 TOI,RTII,PAOVI,PAII;-,-,PR1,PR0 TFLG2 EQU $25 TOF,RTIF,PAOVF,PAIF;-,-,-,- PACTL EQU $26 DDRA7:PAEN:PAMOD:PEDGE:-:-:RTR1:RTR0 * DDRA7 - Data Direction Register for Port A bit 7 * PAEN - Pulse Accumulator ENable * PAMOD - For Pulse Accumulator - See Section 11 of ref.man. * PAMOD = 0 -> Event Count, * PAMOD= 1 -> Gated Time Accumulation * RTR1:RTR0 - Select Real Time Interrupt Rate

  19. Variable Speed Stepper Motor (3) *** HC-COM Routine Addresses & Pseudo Vector Equates .OUTA EQU $FFB8 Print character in A-reg .OUTCRL EQU $FFC4 Output <cr><lf> .OUTSTO EQU $FFCA Output Msg seg (no <cr,lf>) .OUTSTR EQU $FFC7 Output Msg w/leading <cr,lf> PVIC1 EQU $00E8 EVB Pseudo Vector for IC1 PVTOF EQU $00D0 EVB Pseudo Vector for TOF PVOC2 EQU $00DC EVB Pseudo Vector for OC2 PVOC1 EQU $00DF EVB Pseudo Vector for OC1 REGS EQU $1000 * 68HC11 Config Registers base location TOF EQU %10000000 * Timer overflow flag N1 EQU 30 * times for one sec

  20. Variable Speed Stepper Motor (4) OPTION EQU $39 ADCTL EQU $30 ADR1 EQU $31 ADSET EQU %00000100 * A/D input on PE-4 CCF EQU %10000000 * Conversion complete flag ADPU EQU %10000000 * A/D power up bit * * * Monitor Equates OUTLHF EQU $FFB2 Print left half OUTRHF EQU $FFB5 Print right half CRLF EQU $FFC4 Print CRLF

  21. Variable Speed Stepper Motor (5) *** RAM Variable Assignments ORG RAM Start variables in EVB RAM (upper half) JMP START HDLY RMB 2 Half-cycle delay (in 0.5mS increments) * Some routines use only first 5 bytes of DBUFR ADCVAL RMB 1 StepDirn RMB 2 StepPtr RMB 2 * Pointer to items in following table StepTable FCB %0001000, %0100000, FCB %0010000, %1000000, StepEnd EQU *

  22. Variable Speed Stepper Motor (6) START: TOP5 LDS #$0047 * Top of User's Stack area on EVB LDD #$0 STD StepDirn LDD #$8000 STD HDLY LDAA #$7E * Jump (extended) Opcode STAA PVOC2 * Pseudo Vector see manual text LDX #SV5OC2 * Address of OC2 service routine STX PVOC2+1 * Finish jump instruc to TOF svc

  23. Variable Speed Stepper Motor (7) LDX #REGBAS * Point to 68HC11 configuration register block LDAA #%0000000 * STAA OC1M, X * Output Compare Mask = 0 for all OCs LDAA #%0000000 * OM2:OL2 = 0:1 STAA TCTL1,X * SET All timers not connected to outputs LDAA #%1000000 * OM2:OL2 = 0:1 STAA TFLG1,X * Clear any pending,OC2F STAA TMSK1,X * Enable OC2 interrupts CLI * Enable Interrupts LDX #StepTable STX StepPtr * StepPtr -> Start of stepper table values

  24. Variable Speed Stepper Motor (8) LDX StepPtr * Get our table pointer -> X LDAA 0, X * Get the contents of the table -> Acc A LDX #REGBAS * Get configuration register base address -> X STAA PORTA, X * Store initial Stepper motor position LDAA #%11111000 STAA OC1D, X STAA CFORC, X BSET OPTION,x ADPU * Power up the ADC * JSR delay100us * Wait for Charge Pump to stabilise

  25. Variable Speed Stepper Motor (9) * Start the conversion SCAN=0, MULT=0 FOREVER: * Beginning of LOOP-FOREVER LDAA #ADSET * Select ADC input from Port E-4 STAA ADCTL,x * Signal ADC to start conversion * Wait until conversion done convwait: BRCLR ADCTL,x CCF convwait * Get the input and print it using the BUFFALO Monitor LDAA ADR1, x * Get ADC converted input voltage value

  26. Variable Speed Stepper Motor(10) PSHA SUBA #$80 STAA ADCVAL * Store for ISR use BPL PlusOne BMI MinusOne LDD #0 BRA StorDirn * If 0, store 0 PlusOne: LDD #1 BRA StorDirn MinusOne: NEGA * A = -A STAA ADCVAL * Store for ISR use LDD #-1

  27. Variable Speed Stepper Motor(11) StorDirn: STD StepDirn LDAA ADCVAL SUBA #$7F NEGA ASLA LDAB #0 STD HDLY * Speed - save delay PULA TAB * save it (A) in B JSR OUTLHF * output high nybble TBA * restore it to A JSR OUTRHF * output low nybble JSR CRLF * output carriage return - line feed

  28. Variable Speed Stepper Motor(12) * Clear the TOF to start the delay JSR delay100us BRA FOREVER * loop forever

  29. Variable Speed Stepper Motor(13) *** * SV5OC2 - Output Compare 2 service routine * Called at each OC2 interrupt. *** SV5OC2: LDD HDLY * Get delay time for 1/2 cycle LDX #REGBAS ADDD TOC2,X * Add HDLY to last compare value STD TOC2,X * Update OC2 (schedule next edge) BCLR TFLG1,X $BF * Clear OC2F LDD StepPtr * X = Table Pointer ADDD StepDirn * 1, 0 or -1 XGDX

  30. Variable Speed Stepper Motor(14) CPX #StepEnd * If at end of table, then wrap to start BLT NoWrap LDX #StepTable * by Re-Loading the starting address of table BRA StorePtr NoWrap: CPX #StepTable * If before start of table, then wrap back to end BGE NoWrapBack LDX #StepEnd-1 * by Loading the ending address of table NoWrapBack: StorePtr: STX StepPtr * Save next address LDAA 0, X * A = Next Stepper Value

  31. Variable Speed Stepper Motor(15) * LDX #REGBAS STAA REGBAS+PORTA * activate next stepper coil RTI ** Return from OC2 service **

  32. Variable Speed Stepper Motor(16) * ------------------------------------------------------------------------------------ * This subroutine delays (a little over) 100 micro-seconds * ------------------------------------------------------------------------------------ delay100us: PSHA * save Accumulator A * * Generate a "short" delay > 100 microsec LDAA #40 * 40 loops for 200 clock cycles at 0.5 micro seconds/clock DELAYLOOP: DECA * BNE DELAYLOOP PULA * restore Accumulator A RTS *

  33. Analog to Digital Converter • Analog to Digital Converter section of 68HC11 • Requires 32 E-clock cycles to complete a conversion • 8-bit successive approximation converter. • Uses Charge re-distribution for manufacturability reasons. • As it is based upon capacitance it automatically includes Sample & Hold functionality

  34. Analog to Digital Converter • Analog switches are used to provide ADC internal capacitor switching and input multiplexor selection switching. • Uses internal charge pump -> 7 to 8V • Provides high gate voltages to operate analog switches - guarantees low impedance. • must be enabled (disabled at reset) • A/D Power Up (ADPU) control bit • after starting charge pump, must delay 100us before using ADC

  35. Analog to Digital Converter • Uses clock sources - must be selected • Four channels are converted in sequence with the results provided in registers

  36. ADC - Input Sample VX In the sample phase of the conversion: VX, the input voltage, is used to charge the bottom plate of the capacitors relative to the VL low reference (top plate).

  37. ADC - Sample Time is allowed to elapse for 12 cycles, sufficient time for VC, the voltage on the capacitors, to charge to VX - VL. Working with ratios of capacitances. Total Charge is Q = 8 + 4 + 2 + 1 + 1 = 16 units. The Charge Q = 16 (VX - VL). Setting VL =0 volts => Q = 16 VX.

  38. ADC - Hold In the hold phase of the conversion: The charge remains on the capacitors, and the capacitors bottom plate (reference) is shifted to VL. QH = - 16 Vi (assuming VL =0). Now Vi = - (VX - VL).

  39. ADC - Conversion (1)

  40. ADC - Conversion (2) In the Successive Approximation phase of the conversion: The voltage on the capacitors, is re-distributed between the 1 unit capacitor, and the VH reference voltage. The ratio of capacitance determines Vi = (VH/VL) CSEL/C1. The resulting comparator input voltage is set reflects the input Resistive losses and timing are ignored to simplify analysis.

  41. ADC - Conversion (3) Starting with the 8 unit capacitor (MSB), it is switched VH. The charge is Q = 8 (VH - Vi) + 8 (VL - Vi). Q = 8VH - 16Vi assuming Vi = 0. The ratio of capacitance determines Vi = (VH/VL) CSAR/C1. The resulting comparator input voltage is set reflects the input ratio. If the VX < 8/16 (VH - VL) then Vi > VL and the comparator will output a 1. C8 is set to VH, and a 1 is saved in the MSB of the Successive Approximation register (SAR). Conversely if VX > 8/16 (VH - VL) then the comparator will output a 0. C8 is set to VL, And a 0 is saved in the MSB of the Successive Approximation register.

  42. ADC - Conversion (4) Next the 4 unit capacitor (MSB), the capacitor is switched VH. The resulting comparator input voltage is set reflects the input ratio. And the SAR will save the value of the next most significant bit. The ADC continues through the rest of the bits until all capacitors have been set and the SAR holds the value of the conversion. Upon conversion completion: VX = (VH - VL) x (SAR / 256)

  43. ADC - OPTION register Setting the ADPU bit = 1 turns on the on-chip charge pump. The CSEL Control Bit selects which charge pump is activated: 0 - ADC (highest ADC accuracy) 1 - EEPROM (needed for EEPROM efficiency)

  44. ADC - ADCTL register The ATCTL Control Register Specifies Channel Assignments The CCF flag is set to 1 upon completion of 4 conversions, so we can wait for conversion complete using the BRCLR instruction. If the SCAN bit = 1, continuous conversions occur and the CCF bit is always 1. CCF can only be read. Bits 0..5 are read/write.

  45. ADC - SCAN bit • SCAN - Continuous Scan Control • If SCAN=0, four conversions are performed, filling the four result registers. • If SCAN=1, then the A-D conversion continues in a round-robin fashion, and the result registers are updated (but the CCF bit remains set). • CD = 0, CC=0 -> AN0..AN3 in ADR1..ADR4 • CD=0, CC = 1 -> AN4..AN7 in ARD1..ADR4

  46. ADC - MULT bit • MULT - Multiple Channel Control • If the MULT bit=0, then a single channel is converted and the result stored. • If MULT=1, then a conversion is performed on each channel in a group of 4 channels

  47. ADC - Channel Assignments

  48. ADRx - AD Result Registers • The ADRx Results registers receive the converted level from the ADC. • ADR1 - $1031 • ADR2 - $1032 • ADR3 - $1033 • ADR4 - $1034

  49. ADC Code (1) • REGS EQU $1000 ; Registers • TOF EQU %10000000 ; Timer overflow flag • N1 EQU 3030 ; times for one sec • TFLG2 EQU $25 • OPTION EQU $39 • ADCTL EQU $30 • ADR1 EQU $31 • ADSET EQU %00000100 ; A/D input on PE-4 • CCF EQU %10000000 • ; Conversion complete flag • ADPU EQU %10000000 ; A/D power up bit

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