Frequency Counter


+ Reply to Thread
Results 1 to 16 of 16
  1. #1
    Join Date
    Jun 2007
    Location
    Merango, IL
    Posts
    13

    Default Frequency Counter

    Hello Everyone,

    I'm new to this forum and PIC BASIC PRO. I do although have some background in PICs and other forms of programming for them.

    I have a question about a PIC12F683 program I'm writing. I believe the internal clock is 4MHz, typically you set it a different way, but the guy before me said what's in the "Define PIC Internals" will do it. What I'm trying to do is count the number of pulses coming into an input on the PIC from a hall effect sensor. The frequency should be nothing faster than 2kHz. Basically the hall effect will be like giving a position based off of counts, and I will be outputting a 2kHz PWM wave with the number of counts determining the duty cycle.

    I would do a COUNT function but the only problem is I need to be looking at the pulses coming in all the time while changing the duty cycle based on the counts I have. I don't want to miss any of the counts and I'm worried if I make the processor sit and just count pulses I will have to update the duty cycle and while I'm doing so miss a couple counts. I might be thinking way to hard about this and missing a very easy way to complete it. The PWM signal does not take many cycles to update so I might be able to use the COUNT function but I'm unsure.

    Below is the code I have. All this is suppose to do is count the pulses and store them into EEPROM. I only add 1 to position every 10 pulses because of overflow of variable. When I run this I get 00 00 stored into EEPROM. I have gpio.2 tied directly to +5V and a function generator on gpio.3 at 500 Hz. I usually run the system for 10 seconds as well.

    Any help on this would be appreciated, or just any feedback and ideas. Thank guys, and hopefully I can be a good addition to this forum.

    Anthony Smith

    ************************************************** ***
    ' Define PIC Internals

    @ DEVICE PIC12F683, INTRC_OSC_NOCLKOUT
    ' System Clock options
    @ DEVICE PIC12F683, WDT_ON
    ' Watchdog timer
    @ DEVICE PIC12F683, PWRT_ON
    ' Power-On Timer
    @ DEVICE PIC12F683, MCLR_OFF
    ' Master Clear Options
    @ DEVICE PIC12F683, BOD_ON
    ' Brown-Out Detect
    @ DEVICE PIC12F683, CPD_OFF
    ' Data Memory Code Protect
    @ DEVICE PIC12F683, PROTECT_OFF
    ' Program Code Protection

    ' Define Hardware Variables


    ' Define Software Variables
    Position VAR WORD

    Shrink VAR BYTE

    WasLow VAR BIT

    ' Initialize PIC Configuration
    CMCON0 = 7

    TRISIO = %00011110
    'WPU = %00011111


    Position = 0
    WasLow = 0
    Shrink = 0
    PAUSE 50

    MainLoop:
    IF gpio.3 = 1 AND WasLow = 0 THEN
    IF gpio.2 = 1 THEN
    Shrink = Shrink + 1
    ELSE
    Shrink = Shrink - 1
    ENDIF
    WasLow = 1
    ENDIF

    IF Shrink = 10 THEN
    Position = Position + 1
    Shrink = 0
    ENDIF

    IF gpio.3 = 0 THEN
    WasLow = 0
    ENDIF

    IF Shrink = -10 THEN
    Position = Position - 1
    Shrink = 0
    ENDIF

    WRITE 0, Position.Byte1
    WRITE 1, Position.Byte0


    GOTO MainLoop

    ************************************************** ****

  2. #2
    skimask's Avatar
    skimask Guest

    Default

    Break it down, make it simple, build it back up.
    Erase the chip, Blank check it, make sure both program and eeprom space reads back as $ff, then try this:

    Code:
    @ DEVICE PIC12F683, INTRC_OSC_NOCLKOUT
    @ DEVICE PIC12F683, WDT_ON
    @ DEVICE PIC12F683, PWRT_ON
    @ DEVICE PIC12F683, MCLR_OFF
    @ DEVICE PIC12F683, BOD_ON
    @ DEVICE PIC12F683, CPD_OFF
    @ DEVICE PIC12F683, PROTECT_OFF
     
    temp var byte
    temp2 var byte
    ledpin var gpio.(pick a pin)
    output ledpin
    
    main:
    'show a heartbeat for the program on an LED to make sure something is happening
    temp2 = temp2 + 1 : ledpin = temp2.0
    
    for temp = 0 to 255 : write temp, temp : next temp : goto main
    end
    Hook an LED to a pin, let it blink a few times, then do a readback on the PIC. That should tell you if your eeprom statement is working in the first place. Then build it back up...

  3. #3
    Join Date
    Sep 2004
    Location
    montreal, canada
    Posts
    6,898

    Default

    The internal oscillator is set @4MHz by default, you can set OSCCON register to go to 8MHz.

    As usual i'll suggest you to use a internal Timer (TMR0 or TMR1) as counter. Yes you'll have to use the dedicated pins for that... no harm at all, you have tons of benefits.
    1. it runs in background
    2. it's more accurate
    3. use less code space
    4. more flexible

    This PIC have this cute and handy CCP module, so you'll be able to generate the PWM signal really easy using HPWM or by setting the according register manually. This also run in background.

    HTH
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  4. #4
    Join Date
    Jun 2007
    Location
    Merango, IL
    Posts
    13

    Default

    To Skimask:
    I tried out the code you gave me and it did write through the EEPROM like it was suppose to. I re-wrote the code I had and it gives me 00 00 when I do not move any of the inputs around at all if I pull the Pulse Wire in and out of ground it seems to give me random values not how many time I pull it in and out, it does seem kind of close though. The code is posted below if you see a problem with it. Thanks for your help btw. I've been working on this all day now and can't seem to get any repeatability.

    *************************************************
    @ DEVICE PIC12F683, INTRC_OSC_NOCLKOUT
    @ DEVICE PIC12F683, WDT_ON
    @ DEVICE PIC12F683, PWRT_ON
    @ DEVICE PIC12F683, MCLR_OFF
    @ DEVICE PIC12F683, BOD_ON
    @ DEVICE PIC12F683, CPD_OFF
    @ DEVICE PIC12F683, PROTECT_OFF

    TRISIO = %11111111

    Location var WORD

    Mult_Count VAR BYTE

    Was_Low VAR BIT

    Pulse var gpio.3
    Direction VAR gpio.5

    Mult_Count = 0
    Location = 0
    Was_Low = 0

    PAUSE 500

    main:

    IF Pulse = 1 AND Was_Low = 0 THEN
    IF Direction = 1 THEN
    Mult_Count = Mult_Count + 1
    ELSE
    Mult_Count = Mult_Count - 1
    ENDIF
    Was_Low = 1
    ENDIF

    IF Pulse = 0 THEN
    Was_Low = 0
    ENDIF

    IF Mult_Count = 10 THEN
    Location = Location + 1
    Mult_Count = 0
    ENDIF

    IF Mult_Count = -10 THEN
    Location = Location - 1
    Mult_Count = 0
    ENDIF

    WRITE 0, Location.Byte1
    WRITE 1, Location.Byte0
    GOTO main
    end

    *********************************************

    To mister_e:

    I can easily change the clock to 8MHz, I should have done that in the first place. The PWM signal I have done as well, using C code on this chip, and it works pretty nicely. I haven't used the timers before though, although I would really like to go this route with this. My only concern would be I need to be able to count up and down and I'm unsure if can I do so with these Timers. Maybe one way to do so would be to call a interrupt when a direction change is seen and save the timer value before resetting it to 0. Then do the math to another variable with the true position value. I'm gonna start reading on it while I'm still at work. Thanks for the idea it sounds like the best way to go. If you have any advice for going about it let me know. Thanks again.

    Anthony

  5. #5
    Join Date
    Jul 2003
    Posts
    2,405

    Default

    See if this helps;

    CMCON0 = 7
    ANSEL = 0

    Comparators & A/D are enabled by default on power-up. To use some pins for
    digital I/O, you need to disable these.
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com

  6. #6
    Join Date
    Aug 2006
    Location
    Look, behind you.
    Posts
    2,817

    Default

    Quote Originally Posted by Asmith View Post
    To Skimask:
    I tried out the code you gave me and it did write through the EEPROM like it was suppose to. I re-wrote the code I had and it gives me 00 00 when I do not move any of the inputs around at all if I pull the Pulse Wire in and out of ground it seems to give me random values not how many time I pull it in and out, it does seem kind of close though.
    Anthony
    It might be working and counting multiple switch closures due to bouncing switch contacts (noise).
    If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
    .
    Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
    .
    There simply is no "Happy Spam" If you do it you will disappear from this forum.

  7. #7
    Join Date
    Nov 2003
    Location
    Greece
    Posts
    3,104

    Default

    Quote Originally Posted by Asmith View Post

    IF Mult_Count = -10 THEN
    Location = Location - 1
    Mult_Count = 0
    ENDIF
    Are you sure that PBP can do negatives???

    Ioannis

  8. #8
    Join Date
    Jun 2007
    Location
    Merango, IL
    Posts
    13

    Default

    Bruce:
    Thank you I did forget to set up those two registers. I will fix that.

    Joe:
    I'm using a function generator on the input with a scope on it as well and there is no bouncing on the pin. In the end it will be from a hall effect switch which also should not have any bouncing.

    Ioannis:
    I believe PBP will do negative numbers, Location should never be a negative number anyways as 0 would be the lowest number of counts you can have it will be zero we it is set up.

    I think I'm going to try and use the internal timer which I haven't been able to work on it much as work has me burried. I did have some time to write out some code. I will post is below, if you guys would like to comment on it I would appreciate it. It might be a little chopy at the moment though.

    ************************************************** *****
    @ DEVICE PIC12F683, INTRC_OSC_NOCLKOUT
    @ DEVICE PIC12F683, WDT_ON
    @ DEVICE PIC12F683, PWRT_ON
    @ DEVICE PIC12F683, MCLR_OFF
    @ DEVICE PIC12F683, BOD_ON
    @ DEVICE PIC12F683, CPD_OFF
    @ DEVICE PIC12F683, PROTECT_OFF

    '* Hardware Setups *

    INTCON = %10001000
    PIE1 = %00000000
    PIR1 = %00000000
    OSCCON = %01110000

    '* I/O Pin Descriptions Below *
    '* PIN 1 - VDD - 5V *
    '* PIN 2 - T1CK1 - Input - Pulses from Hall Effect *
    '* PIN 3 -
    '* PIN 4 - GP3 - Input for the direction of the Hall Effect *
    '* PIN 5 - CCP1 - PWM Output to the Analog converter *
    '* PIN 6 -
    '* PIN 7 -
    '* PIN 8 - VSS - Ground *

    TRISIO = %00101000
    WPU = %00000000
    IOC = %00001000

    '* Timer Setup *
    T1CON = %00100111



    Location var WORD

    Mult_Count VAR BYTE

    Was_Low VAR BIT

    Pulse var gpio.3
    Direction VAR gpio.5

    Mult_Count = 0
    Location = 0
    Was_Low = 0

    PAUSE 500

    main:


    GOTO main
    end

    ************************************************** ***

  9. #9
    skimask's Avatar
    skimask Guest

    Default

    Quote Originally Posted by Asmith View Post
    Ioannis:
    I believe PBP will do negative numbers, Location should never be a negative number anyways as 0 would be the lowest number of counts you can have it will be zero we it is set up.
    Sure, PBP and assembly both will do negative numbers, but they won't show up the way you want them to...i.e.:

    5 - 6 = -1, but PBP will show 255 (for a byte variable), 65535 (for a word variable).

    You're going to want to add something like this to your program in post #4:

    main:
    IF Pulse = 1 AND Was_Low = 0 THEN
    IF Direction = 1 THEN
    Mult_Count = Mult_Count + 1
    ELSE
    if mult_count > 0 then mult_count = mult_count - 1
    ENDIF
    Was_Low = 1
    ENDIF
    ...............

    IF Mult_Count = -10 THEN(statement won't work the way you want it to in PBP)
    Location = Location - 1
    Mult_Count = 0
    ENDIF

  10. #10
    Join Date
    Aug 2006
    Location
    Look, behind you.
    Posts
    2,817

    Default

    Quote Originally Posted by Asmith View Post
    Bruce:

    Joe:
    I'm using a function generator on the input with a scope on it as well and there is no bouncing on the pin. In the end it will be from a hall effect switch which also should not have any bouncing.




    ************************************************** ***
    It was worth checking.
    JS
    If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
    .
    Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
    .
    There simply is no "Happy Spam" If you do it you will disappear from this forum.

  11. #11
    Join Date
    Jun 2007
    Location
    Merango, IL
    Posts
    13

    Default

    Hello again everyone. I've been trying to complete my task using the timer option that mister_e informed me about. I'm not sure what I'm doing wrong, for some reason I get half the number of pulses counted as the frequency I'm running at. It's this way at every frequency. Maybe it's just been a long day, or I'm misunderstanding something in the book. I tried to mess with the prescale, but it only adds that extra to the already multiplier. The Code is posted below. Thank you everyone who has helped me out.

    Anthony

    Code:
    @ DEVICE PIC12F683, INTRC_OSC_NOCLKOUT
    @ DEVICE PIC12F683, WDT_ON
    @ DEVICE PIC12F683, PWRT_ON
    @ DEVICE PIC12F683, MCLR_OFF
    @ DEVICE PIC12F683, BOD_ON
    @ DEVICE PIC12F683, CPD_OFF
    @ DEVICE PIC12F683, PROTECT_OFF
    
    '*                         Hardware Setups                      *
    
    INTCON = %10001000
    OSCCON = %01110000
    
    '*                   I/O Pin Descriptions Below                 *
    '*  PIN 1 - VDD - 5V                                            *
    '*  PIN 2 - T1CK1 - Input - Pulses from Hall Effect             *
    '*  PIN 3 - 
    '*  PIN 4 - GP3 - Input for the direction of the Hall Effect    *
    '*  PIN 5 - CCP1 - PWM Output to the Analog converter           *
    '*  PIN 6 - 
    '*  PIN 7 - 
    '*  PIN 8 - VSS - Ground                                        *
    
    TRISIO = %00111000
    'IOC = %00001000
    
    '*                           Timer Setup                        *
    T1CON = %00000110
    TMR1H = 0                             
    TMR1L = 0
    
    PAUSE 500
    
    
    T1CON.0 = 1
    PAUSE 1000
    T1CON.0 = 0
    WRITE 0, TMR1H
    
    WRITE 1, TMR1L
    
    end

  12. #12
    Join Date
    Jul 2003
    Location
    Colorado Springs
    Posts
    4,959

    Default

    With OSCCON = %01110000, the internal oscillator will be running at 8Mhz.

    But the default setting for PBP is 4Mhz.
    So the PAUSE 1000 is only pausing for 1/2 second instead of a whole second.
    Which then only allows it to count half of the pulses.

    ADD
    Code:
    DEFINE OSC 8
    <br>
    DT

  13. #13
    Join Date
    Jun 2007
    Location
    Merango, IL
    Posts
    13

    Talking

    Darrel,

    Thank you, I didn't even think of that while I was doing this code. It makes a lot more sense now. Thank you again.


    I have one more question, well it's more of something going on with PBP. I have about 30 PCB board designs and Software for each of them. I have all the file to each board in a dedicated folder including the sch, pcb layout, and PBP files. In this one folder the board has 2 PICs onboard and when I try to compile one it overwrites all the files of the other ones, except for the pbp file. Also, what is stranger is that it takes my sch file and renames it after the file I just compiled, and the sch file has nothing to do with pbp. Has anyone ever seen this occur. It's only on this one folder so it's not a big deal I just made a seperate folder for each PIC inside the main folder.

    Again thank you for all the help everyone. I appreciate the support. Hopefully this new project of mine will continue smoothly for a while.

    Anthony Smith

  14. #14
    Join Date
    Jul 2003
    Location
    Colorado Springs
    Posts
    4,959

    Default

    Yeah, isn't that annoying?
    I lost several files before realizing what was going on.

    When PBP does a compile, it first deletes all the files generated on the last compile.
    But, instead of being Smart about it and verifiying the filenames it needs to delete, it just deletes everything with the same Name.

    But here's the problem ... it uses the old DOS style names when it does it. So everything with the same 8 characters in the beginning of the filename also get deleted.

    Let's say you have the following files ...

    TestProg.PBP
    TestProg.ASM
    TestProg.LST
    TestProg.XRF
    TestProg.HEX
    TestProg.XLS
    TestProg.BRD

    When you compile TestProg.PBP, you will lose the Excel and PC board files (.XLS and .BRD) because they have the same Name.

    You would also lose these files, if they were there.

    TestProg_Try2.HEX
    TestProgram.ASM
    TestProgram3.INC

    or any other file with the same first 8 characters, that isn't a .BAS or .PBP.

    So, you're right. It's best to have each program in it's own folder.
    And, be sure to name anything else in that folder something different than the main program.


    HTH,
    DT

  15. #15
    Join Date
    Nov 2003
    Location
    Greece
    Posts
    3,104

    Default

    Yeah, it is easy to do a:

    del testprog.*

    than check each file with its own extension.

    Now I understand why I lost a project sometime ago and never knew why... pitty.

    Thanks Darrel.

    Ioannis

  16. #16
    Join Date
    Jun 2007
    Location
    Merango, IL
    Posts
    13

    Default

    Thank you for the insight on this issue Darrel. I understand what is going on now. I will be sure to keep everything seperated, or maybe just start the file name with the specific file task instead of end with it. Thanks again.

    Anthony

Similar Threads

  1. Conway's Game Of Life
    By wellyboot in forum mel PIC BASIC Pro
    Replies: 45
    Last Post: - 28th May 2020, 06:14
  2. Audio Frequency Counter
    By mister_e in forum Code Examples
    Replies: 8
    Last Post: - 29th July 2009, 08:25
  3. frequency counter help and pointers
    By comwarrior in forum General
    Replies: 2
    Last Post: - 30th June 2009, 11:51
  4. Microcontroller with 2 way paging application problem
    By oneohthree in forum mel PIC BASIC Pro
    Replies: 30
    Last Post: - 20th April 2007, 17:27
  5. Frequency Counter using PIC and PicBasic
    By PICtron in forum mel PIC BASIC Pro
    Replies: 31
    Last Post: - 28th January 2005, 06:20

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts