Project Title:
Week of: January 25th, 2000
Engineers:
Megan Bern and Ritesh Patel
Advisor’s Signature: _________________
Grade: _______
=================================================================
Objective:
For the week of February 1st, 2000, our objective was to retest the interface hardware that converted the D/A converter output to the power amplifier and continue writing code for the digital filter.
Progress:
Hardware:
The circuit for the D/A to power amplifier conversion is shown in Figure 1. The parameters of the circuit were measured to verify that they were close to being exact values. This was done because of the previous results recorded for this circuit. The measured values for these parameters are listed in Table 1.
Table 1:
Measured Parameter Values
R1=1,001W
R2=1,002W
R3=100,090W
R4=99,980W
R5=99,950W
R6=100,370W
R7=200,250W
Figure 1:
D/A Converter to Power Amplifier Design Interface
The inputs and outputs of the circuit were measured. The new recorded values are listed in Table 2.
Table 2:
Inputs vs. Outputs for D/A to AMP
Potentiometer Calculated Experimental
These values are much better than the previous week. The maximum difference is 22mV. Three op-amps would give a maximum error of 60mV. The maximum difference is within the maximum error. The final schematics that will be used for interface the potentiometer and the power amplifier to the EMAC board are shown in Figures 1 and 2.
Figure 2:
Final schematic for P-to-A/D conversion
Software:
The digital filter
was simulated using simulink. Figure 3 shows the block diagram used
for the simulation.
Figure 3:
Simulink Block Diagram
By double clicking on the
Sine Wave box, a window of parameters is displayed. Table 3 lists
the parameters that were used.
Table 3:
Sine Wave Parameters1. Amplitude=1
2. Frequency(rad/sec)=20*6.28
3. Phase(rad)=0
4. Sample time=0.005secThe transfer function G(z) for a 20 Hz pole is
By double clicking on the Discrete Transfer Fcn box, a window of parameters is displayed. Table 4 lists the parameters that were used.
Table 4:
Discrete Transfer Fcn Parameters1. Numerator=[125 125]
2. Denominator=[500 -250]
3. Sampling time=0.005
The simulation was ran by clicking on simulation and choosing START. After the simulation is done, double clicking on the Scope box will display the results. The results for the simulation of Figure 3 is attached to this report. The results show that the output is approximately 0.707 of the input signal. This would be the 3dB down point or the pole location, which was designed to be 20Hz.
The code for the digital filter was written. To simulate and run the code, the following steps listed in Table 5 must be done.
Table 5:
Steps for Simulation of Code1. Open my computer.
2. Open H drive.
3. Open Ee451 folder.
4. Copy emac folder into C drive.
5. Place file of code in emac folder in C drive.
6. Left click test.bat.
7. Enter asm51 "filename", save, close, and double click test.bat.
8. Open Procomm if no errors.
9. Hit space bar twice.
10. Plug in or reset EMAC board.
11. Hit space bar twice.
12. Enter DOWNLOAD and hit enter.
13. Hit Page Up key and select #7.
14. Enter filename and hit enter.
15. Enter MGO 8000 and hit enter.These steps will run your code. We found that the output after running the code was not acting like a digital filter. The code was troubleshooted by using breakpoints. To set breakpoint the following steps listed in Table 6 must be executed.
Table 6:
Breakpoint Steps1. After entering the filename in Procomm, enter BR0="address to break at" and hit enter.
2. Type "GO FROM 8000 TIL PROG".These steps will run the code until it hits the specified address. After many changes the written code implemented a digital filter. The 0.707 or 3dB down point was displayed on an oscilloscope. This is shown in Figure 4. The code used to implement this output is attached to this report.
Figure 4:
Digital Filter Input vs. Output at 3dB DownThe pole was located at 53.45 Hz. The code was written for a 20Hz pole. This means the code must be written to consider any unnecessary rounding or remainders that need to be used. This will be done next week.
;Ritesh Patel & Megan Bern
;Program1
;01/25/00
;generates 10Hz square wave
;A/D and D/A conversion
;Digital Filter [Yn=.25Rn + .25(Rn-1)+.50(Yn-1)]
;include(mod515)
$INCLUDE(mod515)
;include(digital)
$INCLUDE(digital.asm)STARD EQU 8000H ;start address for program
ORG stard
JMP SETUP;Interrupt Jump Table
org stard+2BH ;TF2 + EXF2 interrupt
AJMP TMR2SRV ; Jump to timer 1 interrupt;-----------------------------------------------------------------
TMR2SRV: ;timer 2 service every 50 ms
MOV A,#2 ; load ACC for channel 2
CALL adcin ; call converter subroutine
; value in ACC
CALL da_out ; write to D/A converter, Chn 0CPL p4.1 ;generate pulse
CLR TF2 ;clear interrupt flag
RETI
; ADCIN subroutine
; Return ACC with the 8 bit A/D conversion from the channel selected by ACC
;
ADCIN:
ANL A,#00000111B ; ONLY 8 CHANNELS
ANL ADCON,#11000000B ; MODE FOR A/D CONVERSION: SINGLE
ORL ADCON,A ; "OR" IN THE CHANNEL
MOV DAPR,#0 ; START CONV W/NO REF VOLTAGE
JB BSY,$ ; LOOP TILL CONVERTED
MOV acc,ADDAT ; ACC = CONVERSION
LOOP:
MOV IP_1,IP ;Cutrrent inpt stores for
;later use
;MOV A,#07FH ; debugMOV IP,a
MOV b,#4h ;Store 4 in accumulator b
DIV ab ;Divide a by b
MOV R4,a
MOV a,b
CLR C
SUBB a,#2
JC HERE
JZ THERE
JNZ THERE
THERE:
MOV a,R4
ADD a,#1
HERE:
MOV a,R4
MOV R2,a ;Store value in R1
MOV a,IP_1
MOV b,#4h
DIV ab
MOV R4,a
MOV a,b
CLR C
SUBB a,#2
JC HERE1
JZ THERE1
JNZ THERE1THERE1:
MOV a,R4
ADD a,#1HERE1:
MOV a,R4
MOV R3,a ;store past input value in R2
MOV OP_1,OP ;store current output for later use
MOV a,OP_1
MOV b,#2h
DIV ab
MOV R4,a
MOV a,b
CLR C
SUBB a,#2
JC HERE3
JZ THERE3
JNZ THERE3THERE3:
MOV a,R4
ADD a,#1HERE3:
MOV a,R4
ADD a,R2
ADD a,R3
MOV OP,a ;Output store in R4
;Output store for later use
RET
; da_out subrountine
; write value in ACC to D/A channel specified below
da_out: MOV P2,#DA_0 ; point to D/A channel 0
MOVX @R1,a ; write data
RET
;***********************************************
;
; Intialization Code
;
;***********************************************SETUP:
MOV IEN0,#0 ;Disable ALL INTS
MOV SP,#70H ;Initialize STACKSETB P5.5 ;Do a reset
CLR P5.5 ;bring it low
SETB P5.0 ;make A16 of 128K Ram, high
SETB P5.2 ;disable EEPROM
CLR P5.1 ;new port 5.1 for D/A
;END 80535 Stuff
MOV R0,#7FH ;CLEAR 128 BYTES OF RAMclr_ram: MOV @R0,#0
DJNZ R0,clr_ram
SETB T2CON.0 ; timer 2: 16 bit operation
SETB T2CON.4 ; and auto-reload mode
MOV TH2,#0F6H ; load timer 2 registers
MOV TL2,#0F2H
MOV CRCH,#0F6H ; load capture registers
MOV CRCL,#0F2H ; timer 2SETB ET2 ;enable timer 2 ovf int
SETB EAL ; enable all interrupts
Digital:
MOV IP,#0 ;Initialize IP
MOV IP_1,#0 ;Initialize IP_1
MOV OP,#0 ;Initialize OP
MOV OP_1,#0 ;Initialize OP_1
main: jmp main
END
