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Number output to an LCD — Parallax Forums

Number output to an LCD

ArchiverArchiver Posts: 46,084
edited 2001-10-24 16:47 in General Discussion
Gentlemen,

I need your help again.

I can display all the text in the world to the LCD, but it doesnt like
variables (especially with numbers)

I have looked for a conversion instruction, but was unable to find one. I
need to convert a 10 bit ADC to display it on the LCD. Eventually I will
also need to do math on it, but FP numbers are difficult in PBasic.

Thanks,

Mark

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-10-24 15:04
    LCDs only display charcters, so to display a number, you must convert it to a
    string of characters. It's not too tough -- you can use a loop with the DIG
    operator to get the individual digit value in each place, then add "0" (ASCII
    48) to convert it to a character -- then send it to the LCD.

    Here's a code fragment that assumes your number is in a variable called myNum.

    WriteNumber:
    FOR x = 4 TO 0 ' scan 5 possible digits
    in number
    char = myNum DIG x + "0" ' convert digit to ASCII code
    GOSUB LCDwrite ' write to LCD
    NEXT
    RETURN


    -- Jon Williams
    -- Parallax



    In a message dated 10/24/01 8:19:22 AM Central Daylight Time,
    madams@a... writes:


    > I can display all the text in the world to the LCD, but it doesnt like
    > variables (especially with numbers)
    >
    > I have looked for a conversion instruction, but was unable to find one. I
    > need to convert a 10 bit ADC to display it on the LCD. Eventually I will
    >




    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2001-10-24 15:14
    That is exactly what I was looking for, thanks!

    Now what about dividing a 10 bit number by 0.0733

    Mark
    Original Message
    From: jonwms@a... [noparse]/noparse]SMTP:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=yk9_B4RRV9s9GBLGY-Fierq1lwt8-bS-T3SSRWALJPjfpEqbrnplSV6AroojyPT2XnoDv0_NNA]jonwms@a...[/url
    Sent: Wednesday, October 24, 2001 9:05 AM
    To: basicstamps@yahoogroups.com
    Subject: Re: [noparse][[/noparse]basicstamps] Number output to an LCD

    LCDs only display charcters, so to display a number, you must convert it to a
    string of characters. It's not too tough -- you can use a loop with the DIG
    operator to get the individual digit value in each place, then add "0" (ASCII
    48) to convert it to a character -- then send it to the LCD.

    Here's a code fragment that assumes your number is in a variable called myNum.

    WriteNumber:
    FOR x = 4 TO 0 ' scan 5 possible digits
    in number
    char = myNum DIG x + "0" ' convert digit to ASCII code
    GOSUB LCDwrite ' write to LCD
    NEXT
    RETURN


    -- Jon Williams
    -- Parallax



    In a message dated 10/24/01 8:19:22 AM Central Daylight Time,
    madams@a... writes:


    > I can display all the text in the world to the LCD, but it doesnt like
    > variables (especially with numbers)
    >
    > I have looked for a conversion instruction, but was unable to find one. I
    > need to convert a 10 bit ADC to display it on the LCD. Eventually I will
    >




    [noparse][[/noparse]Non-text portions of this message have been removed]


    To UNSUBSCRIBE, just send mail to:
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  • ArchiverArchiver Posts: 46,084
    edited 2001-10-24 15:25
    In a message dated 10/24/01 9:16:34 AM Central Daylight Time,
    madams@a... writes:


    > Now what about dividing a 10 bit number by 0.0733
    >

    Dividing by 0.0733 is the same as multiplying by 13.6426. The BASIC Stamp
    has an operator called star-slash (*/) that can be used to multiply
    fractional values. The fractions are expressed in 1/256. In the case above,
    13.6426 * 256 = 3492. Your code, then, is this:

    newVal = oldVal */ 3492

    You will have to deal with possible rounding and overflow errors. It would
    be best to write some test code and DEBUG the results to make sure they're in
    line with what you expect.

    -- Jon Williams
    -- Parallax

    PS: Tracy Allen is the undisputed best when it comes to Stamp math and
    dealing with high-precision values. You really should visit his site:

    http://www.emesys.com/BS2index.htm





    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2001-10-24 15:57
    I know that have very more precise solutions (look at Tracy Allen web
    site) but if you could tolerate 5% error a quick approach is just
    multiply by 13.
    ACJacques

    Mark Adams wrote:
    >
    > That is exactly what I was looking for, thanks!
    >
    > Now what about dividing a 10 bit number by 0.0733
    >
    > Mark
    >
    >
    Original Message
    > From: jonwms@a... [noparse]/noparse]SMTP:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=NCX4Svf6gA49C9mSheu1RxswrjAKmNCEbJbPNTUZCO4aJLXUxSFq91KRcRmfkPpUObCjFt3kWhs]jonwms@a...[/url
    > Sent: Wednesday, October 24, 2001 9:05 AM
    > To: basicstamps@yahoogroups.com
    > Subject: Re: [noparse][[/noparse]basicstamps] Number output to an LCD
    >
    > LCDs only display charcters, so to display a number, you must convert it to a
    > string of characters. It's not too tough -- you can use a loop with the DIG
    > operator to get the individual digit value in each place, then add "0" (ASCII
    > 48) to convert it to a character -- then send it to the LCD.
    >
    > Here's a code fragment that assumes your number is in a variable called myNum.
    >
    > WriteNumber:
    > FOR x = 4 TO 0 ' scan 5 possible digits
    > in number
    > char = myNum DIG x + "0" ' convert digit to ASCII code
    > GOSUB LCDwrite ' write to LCD
    > NEXT
    > RETURN
    >
    > -- Jon Williams
    > -- Parallax
    >
    > In a message dated 10/24/01 8:19:22 AM Central Daylight Time,
    > madams@a... writes:
    >
    > > I can display all the text in the world to the LCD, but it doesnt like
    > > variables (especially with numbers)
    > >
    > > I have looked for a conversion instruction, but was unable to find one. I
    > > need to convert a 10 bit ADC to display it on the LCD. Eventually I will
    > >
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the Subject and Body
    of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the Subject and Body
    of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
  • ArchiverArchiver Posts: 46,084
    edited 2001-10-24 16:01
    If */ or some of Tracy's tricks won't do it for you, have a look at our
    PAK-I, II, and IX all of which do floating point math.
    http://www.al-williams.com/awce/pak1.htm

    Regards,

    Al Williams
    AWC
    * 8 channels of PWM
    http://www.al-williams.com/awce/pak5.htm

    >
    Original Message
    > From: Mark Adams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=1AAIwdRKbCWoRWlT2AdyUroyAF3djF2MCHJXd0oloE_E2jzIRVnfGLClAfysrV8Tzho2RBCASD-t2Q]madams@a...[/url
    > Sent: Wednesday, October 24, 2001 9:14 AM
    > To: 'basicstamps@yahoogroups.com'
    > Subject: RE: [noparse][[/noparse]basicstamps] Number output to an LCD
    >
    >
    > That is exactly what I was looking for, thanks!
    >
    > Now what about dividing a 10 bit number by 0.0733
    >
    > Mark
    >
    >
    Original Message
    > From: jonwms@a... [noparse]/noparse]SMTP:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=5cHLhWf_5rwKhcZmXJpel0ZtXObKeAi8DCiE3Sh_cPAGyLjkd8nuLRAoyPd2g6D5so9KWdM]jonwms@a...[/url
    > Sent: Wednesday, October 24, 2001 9:05 AM
    > To: basicstamps@yahoogroups.com
    > Subject: Re: [noparse][[/noparse]basicstamps] Number output to an LCD
    >
    > LCDs only display charcters, so to display a number, you must
    > convert it to a
    > string of characters. It's not too tough -- you can use a loop
    > with the DIG
    > operator to get the individual digit value in each place, then
    > add "0" (ASCII
    > 48) to convert it to a character -- then send it to the LCD.
    >
    > Here's a code fragment that assumes your number is in a variable
    > called myNum.
    >
    > WriteNumber:
    > FOR x = 4 TO 0 ' scan 5
    > possible digits
    > in number
    > char = myNum DIG x + "0" ' convert digit to
    > ASCII code
    > GOSUB LCDwrite ' write to LCD
    > NEXT
    > RETURN
    >
    >
    > -- Jon Williams
    > -- Parallax
    >
    >
    >
    > In a message dated 10/24/01 8:19:22 AM Central Daylight Time,
    > madams@a... writes:
    >
    >
    > > I can display all the text in the world to the LCD, but it doesnt like
    > > variables (especially with numbers)
    > >
    > > I have looked for a conversion instruction, but was unable to
    > find one. I
    > > need to convert a 10 bit ADC to display it on the LCD.
    > Eventually I will
    > >
    >
    >
    >
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the
    > Subject and Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the
    > Subject and Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
  • ArchiverArchiver Posts: 46,084
    edited 2001-10-24 16:47
    >In a message dated 10/24/01 9:16:34 AM Central Daylight Time,
    >madams@a... writes:
    >
    >
    > > Now what about dividing a 10 bit number by 0.0733
    > >
    >
    >Dividing by 0.0733 is the same as multiplying by 13.6426. The BASIC Stamp
    >has an operator called star-slash (*/) that can be used to multiply
    >fractional values. The fractions are expressed in 1/256. In the case above,
    >13.6426 * 256 = 3492. Your code, then, is this:
    >
    > newVal = oldVal */ 3492
    >
    >You will have to deal with possible rounding and overflow errors. It would
    >be best to write some test code and DEBUG the results to make sure they're in
    >line with what you expect.
    >
    >-- Jon Williams
    >-- Parallax
    >
    >PS: Tracy Allen is the undisputed best when it comes to Stamp math and
    >dealing with high-precision values. You really should visit his site:
    >
    > http://www.emesys.com/BS2index.htm

    Thanks for the boost, Jon!

    The best precision easily comes from the ** operator. It expresses
    fractions in units of 1/65536, which is in general more accurate than
    1/256. But ** can only do fractions between zero and one, so it
    takes two steps on the Stamp:

    newVal = (oldval * 13) + (oldVal ** 42111)


    0.6425648 * 65536 = 42111

    that is to say, 42111/65536 is close to 0.6425648, within better than
    4 decimal places. With a ten bit number for oldval, it is not going
    to overflow. That is, the maximum value 1024/0.0733 is 13970, less
    than one word in value. The new value has more significant digits
    than the old value, so you could probably round off the last digit.
    The ** operator gives you the extra precision to allow accurate
    rounding.

    -- regards,
    Tracy Allen
    electronically monitored ecosystems
    mailto:tracy@e...
    http://www.emesystems.com
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