A Defines Request

[rmteo]

You can follow the same topic here How do I learn configuration?

[Kirk Fraser]

Dear Dave,

Attached is the latest program. I did add the suggested capacitor between the +-5 supply lines. Somehow I smoked a regulator and PIC trying it. I got new chips and retried our program to flicker the LEDs and that worked fine. I tried the attached program (with your suggested OSC 48 configs ADCON1 and CMCON plus the OSCCON from the LED program) . It sounded like it was driving the valve coil but the 5VDC regulator started to smoke then it settled down and looked ok with one LED lit except the program, the same as the one which works on the stamp, didn't change anything when the POT was turned. Eventually I reloaded the program to make sure I hadn't fried the PIC chip and tried it with a new regulator. This time all three LEDs were on bright and the regulator shot a bit of plastic (about half the front) and hit me in the stomach. Any suggestions?

With assistance from the other forum I located the Bits section and saw the config table. I wonder why the stuff they specify such as config1L PLLDIV has extra syntax like _CONFIG1L, _PLLDIV_1_1L and similar for all specified bits. Where is that documented?

Also, your ADCON1 'Set all I/O's to Digital and CMCON 'Disable Comparators would seem to turn off the analog function needed on pin 2 aka. PORTA.0 which is supposed to read a Pot and Capacitor for the RCTIME command. Could that have anything to do with blowing up the regulator? I'll try it without after posting this.

Thanks,
Kirk

[mackrackit]

I can not look at your current code where I am at. If it were posted inline with code tags I could.

ADCON1 = 15
Turns off the hardware ADC
CMCON = 7
Turns off the hardware comparators.

RCTIME is a software command having nothing to do with the above.

Running the LEDs without a resistor could be overloading the regulator, at least until they pop. Is the schematic posted really what you are working with? Even with a Stamp resistors are needed.

[Kirk Fraser]

Dave,

Retesting confirms, your latest suggestion burned out my regulator and a PIC18F4550 in addition to smacking me in the stomach. (Now I see why your "Wear Safety Glasses" comment is serious.)
ADCON1 = 15 ' Set all I/Os to Digital
CMCON = 7 ' Disable Comparators
Commenting out those two statements got me back to the original post on this thread. Now it simply doesn't work even though the current regulator works shown via voltmenter and PIC works proven by reloading the program.

LED resisters are NOT needed on the Stamp. They were not needed when running the PIC with the LED test either, except to protect the LED's on start up - they worked fine when added after powered up. What LED resistor would you recommend?

The schematic is exactly the same except for the crystal and its caps which aren't needed on the Stamp and the fact I forgot to show a cap across the regulator ground and 5V out, which can be seen in the photo. In fact the photo would be exactly the same when using the Stamp except wires connect the Stamp board with the IRL530's and the POT circuit and the absence of the PIC chip.

So back to the original question for this thread. What do I need to change to make it work? Thanks.

Kirk

PS: I don't know what you mean by code tags but here's my current code.

'Hydraulic S-Curve Swing Test reducing limit shock
'   Chips: PIC 18F4550 2x IRL530
'   Inputs: 10K pot for actuator position
'            ~USB for position control request
'   Outputs: PWM for Proportional Servo-Valve
'            ~USB for position report 
'---------------
INCLUDE "bs2defs.bas"
DEFINE OSC 48
@ __CONFIG   _CONFIG1L, _PLLDIV_1_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
@ __CONFIG   _CONFIG1H, _FOSC_HSPLL_HS_1H
@ __CONFIG   _CONFIG2H, _WDT_OFF_2H & _WDTPS_512_2H
@ __CONFIG   _CONFIG2L, _PWRT_ON_2L & _VREGEN_ON_2L
@ __CONFIG   _CONFIG3H, _PBADEN_OFF_3H & _MCLRE_OFF_3H
@ __CONFIG   _CONFIG4L, _LVP_OFF_4L & _XINST_OFF_4L
'ADCON1 = 15               ' Set all I/Os to Digital
'CMCON = 7                 ' Disable Comparators
OSCCON = %01110000

'INPUT
ArmPosIn      VAR PORTA.0     'Pot for swing arm position

'OUTPUTS for PWM
PWA              VAR PORTC.0
PWB             VAR PORTC.1

'DISPLAY LED's
LGl           VAR PORTA.2 
LRl          VAR PORTA.3 
LYl           VAR PORTA.4 
LGr          VAR PORTB.4 
LRr           VAR PORTB.3 
LYr           VAR PORTB.2 
 
'CONSTANTS
UpState     CON 0
DnState     CON 1

'VARIABLES
ArmPos          VAR WORD
CurrentState      VAR Bit
Charge            VAR Word
ChgLim          VAR Word 
DnLimit     VAR Word
DnTrans     VAR Word     
UpTrans     VAR Word    
UpLimit     VAR Word 
     
'Initialize
Charge = 0
DnLimit = 100
DnTrans = 200
UpTrans = 800
UpLimit = 900

'Main Loop
Begin:
While 0 = 0
LOW LGl
LOW LRl
LOW LYl
LOW LGr
LOW LRr
LOW LYr

  HIGH ArmPosIn                ' charge the cap
  PAUSE 1                      '   for 1 ms
  RCTIME ArmPosIn, 1, ArmPos   ' measure RC discharge time

ChgLim = 1<<8 - 1

IF ArmPos >= UpLimit THEN
    CurrentState = DnState
    ChgLim = 0
    ENDIF
IF ArmPos <= DnLimit THEN
    CurrentState = UpState
    ChgLim = 0
    ENDIF

 IF CurrentState = UpState AND ArmPos < DnTrans THEN
    GOSUB AccelUp
    GOTO Begin
 ENDIF
 IF CurrentState = UpState AND ArmPos < UpTrans THEN
    GOSUB FastUp
    GOTO Begin
 ENDIF
 IF CurrentState = UpState AND ArmPos < UpLimit THEN
    GOSUB DecelUp
    GOTO Begin
 ENDIF
 IF CurrentState = DnState AND ArmPos > UpTrans THEN
    GOSUB AccelDn
    GOTO Begin
 ENDIF
 IF CurrentState = DnState AND ArmPos > DnTrans THEN
    GOSUB FastDn
    GOTO Begin
 ENDIF
 IF CurrentState = DnState AND ArmPos > DnLimit THEN
    GOSUB DecelDn
 ENDIF
Wend

AccelUp:        '100 - 200 -> 0 - ChgLim
Charge = (ArmPos - 100) * (ChgLim / 100)
HIGH LGl
GOSUB Coil_Output
RETURN

AccelDn:        '900 - 800 -> 0 - ChgLim
Charge = ABS (900 - ArmPos) * (ChgLim / 100)
HIGH LGr
GOSUB Coil_Output
RETURN

FastUp:          'max speed
Charge = ChgLim
HIGH LRl
GOSUB Coil_Output
RETURN

FastDn:          'max speed
Charge = ChgLim
HIGH LRr
GOSUB Coil_Output
RETURN

DecelUp:        '800 - 900 -> ChgLim - 0
Charge = (ArmPos - 800) * (ChgLim / 100)
HIGH LYl
GOSUB Coil_Output
RETURN

DecelDn:        '200 - 100 -> ChgLim - 0
Charge = ABS (100 - ArmPos) * (ChgLim / 100)
HIGH LYr
GOSUB Coil_Output
RETURN

Coil_Output:
' PWM output code - 8 bit 
Charge = ABS Charge MAX ChgLim 'Stop negatives when tweaking limits
IF CurrentState = UpState THEN
'Up: Coil A = Charge, B = 0
   PWM PWA,Charge,250
   LOW PWB
ELSE
'Dn: Coil A = 0, B = Charge
   LOW PWA
   PWM PWB,Charge,250
ENDIF
RETURN
END

[cncmachineguy]

Kirk, I agree that Dave's suggestions are spot on. but also no arguing with actual blown up parts. If this were my project, I would start by disconnecting everything and reconnecting it 1 at a time. I would start with the LED's (and add resistors) then I would add the pot section, lastly I would add 1 coil circuit at a time.

I would suspect the answer can be found with the hardware, but sorry I do not know exactly what is wrong. Your pot circuit looks odd to me. I thought the path was Vcc->cap->pot->gnd. with the signal taken from between the cap and potthrough another resistor. Your diagram seems to show the pot parallel with the cap.

There is clearly some direct short somewhere through the guts of the PIC. maybe this has to do with the type of internal circuit for one of the pins. ie: open collector or totom pole.

As for blowing a 7805, I have never acheived that. they have alwys shut down before then. This is why I think a direct short has to be the problem. the current is spiking so fast, it can't turn itself off before destruction.

Keep this in mind also: even though the hardware worked on the stamp, as you know this will be running much faster, so maybe some back emf from the coil or possibly something else. just saying remember all things are not equal


code tags are this: add [code (other bracket), then your code, then bracket /code] and it will put your code in a nice scrollable box

[mackrackit]

I normally use a 470 ohm for the typical LED when the voltage is ~5 , not as bright as could be but safe. Bruce spells it out here.
http://www.picbasic.co.uk/forum/show...6966#post76966

Like Bert said, do one thing at a time. Trouble shooting can be a pain.

[Kirk Fraser]

I'd like to explore my theory first, considering my accomplished tests sufficient proof (so far) that the two global commands don't help in my circuit. What other commands are there to try? What commands would convert or leave the 3 essential pins analog and make the rest digital?

This seems reasonable since the PWM outputs are analog signals and driving the IRL530's with a solid digital on could act like a short, allowing coil current to build and eventually blow things up. This could explain the blown chips with the global commands.

The "normal" inaction with the POT input may also be affected by a more specific analog input, compare, or conversion command. The exact same POT circuit was used successfully with the Stamp, with the exact same RCTIME command. RC means Resistor-Capacitor so it is necessary for them to be in parallel to create a measureable oscillator time change when the POT value changes. I don't know why it is connected to ground instead of 5+ but I got that circuit from Stamp docs. Perhaps a different setting for that pin is needed to accept analog input from ground instead of positive values.

I don't know how the guts of the Analog - Compare commands work, if there's any need to know. I do think finding pin specific commands would be a step toward a solution. What section of the book are those in? Thanks.

[cncmachineguy]

Look up ADCON1 register in the datasheet. to find it faster, make sure bookmarks are on and scroll do the the A/D section. this section will tell you lots of stuff about how the pic does the A/D. the registers are always listed at the end of the section. BTW, within the first few paragraphs it explains how to turn the Analog input on and off to use the pin as Digital or analog. Any way, look up ADCON1 and read which bits need to be on or off, 0 or 1, set or clear.

PWM is not an analog output.

[BobP]

Hi,

Only had time for a quick look. But from what I can see on your diagrams in post 1. The back EMF diodes are not correctly fitted and seem to be connected differently to the prototype board. The diodes should go across the coil contacts with the 'band' connected to the +ive coil side.

This seems reasonable since the PWM outputs are analog signals and driving the IRL530's with a solid digital on could act like a short, allowing coil current to build and eventually blow things up. This could explain the blown chips with the global commands.

The Pulse Width Modulator outputs are digital. The on and off time is variable and is what you adjust within the program. The amount of high back EMF that PWM will generate on this circuit will wreck havoc with the PIC. Move the diodes and test the circuit by replacing the coils with small lamps .

Also good pratice to fit 1k resistors to the gate connections from the PIC as directly connecting the PIC to the FETs can cause a 'lock on'.

Bob.