Reading PINS in a loop?

Vern Graner · 2006-07-05 23:06

Ok, in one of my hare-brained schemes, I'm trying to read a sequence of pins and then act on the values. My original code had big repeating chunks such as this:

IF PIN1 = 1 THEN
  SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", 1, TurnOn]
ELSE
  SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", 1, TurnOff]
ENDIF

IF PIN2 = 1 THEN
  SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", 2, TurnOn]
ELSE
  SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", 2, TurnOff]
ENDIF

IF PIN3 = 1 THEN
  SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", 3, TurnOn]
ELSE
  SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", 3, TurnOff]
ENDIF

IF PIN3 = 1 THEN
  SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", 4, TurnOn]
ELSE
  SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", 4, TurnOff]
ENDIF

So, I envisioned saving memspace and being more efficient by putting this inside a FOR/NEXT loop like this:

FOR cntI = 1 to 4
  IF PIN cntI = 1 THEN
          SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", cntI, TurnOn]
  ELSE
          SEROUT DC16, DC16Baud, [noparse][[/noparse]"!DC16", DC16Addr, "P", cntI, TurnOff]
  ENDIF
NEXT

However, (and maybe I'm a victim of cerebral flatulence here) I can't find a way to use a variable for a pin number! (the above was my first test and it didn't work)

Can someone give me a kick in the shins in the right direction? TIA! [noparse]:)[/noparse]

Vern

PS:

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Vern Graner CNE/CNA/SSE    | "If the network is down, then you're
Senior Systems Engineer    | obviously incompetent so why are we
Texas Information Services | paying you? Of course,if the network
http://www.txis.com        | is up, then we obviously don't need
Austin Office 512 328-8947 | you, so why are we paying you?" ©VLG

Post Edited (Vern) : 7/6/2006 12:16:44 AM GMT

Chris Savage · 2006-07-05 23:13

Vern,

·· Can you clarify...Are you trying to make the outputs of the DC-16 match the inputs at 4 Stamp I/O pins?· If so that can be done with 1 or 2 lines of code.· You're using the P command on the DC-16 to set a pin, but you can set them all at the same time with the S command.· Likewise you can read the pins at the same time on the BASIC Stamp using the IN<register> command, such as INA.· The PIN statement only allows you to define constants, so you can't use it in a variable environment.

BTW - Congrats on your 2nd Nuts & Volts article.

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Vern Graner · 2006-07-06 00:15

Chris Savage (Parallax) said...
Can you clarify...<snip>?

Sure. I think I may have included too much detail as it lost the focus of the question. My bad.

So, forget the DC-16 stuff.. it was only there to illustrate and I think it side tracked. How about this:

I originally wrote large repeating code hunks like this:

IF PIN1 = 1 THEN
  <do some stuff>
ENDIF

IF PIN2 = 1 THEN
  <do some stuff>
ENDIF

IF PIN3 = 1 THEN
  <do some stuff>
ENDIF

IF PIN3 = 1 THEN
  <do some stuff>
ENDIF

So I envisioned putting it in a loop like this:

FOR cntI = 1 to 4
  IF {pin number <a variable>} = 1 THEN
          <do some stuff>
  ENDIF
NEXT

I'm trying to determine how to use a pin# in a comparison, but where the pin number itself is specified in a variable...? Is this possible?

Chris Savage (Parallax) said...
BTW - Congrats on your 2nd Nuts & Volts article.

Thanks! Couldn't have done it without you guys!

Vern

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Vern Graner CNE/CNA/SSE    | "If the network is down, then you're
Senior Systems Engineer    | obviously incompetent so why are we
Texas Information Services | paying you? Of course,if the network
http://www.txis.com        | is up, then we obviously don't need
Austin Office 512 328-8947 | you, so why are we paying you?" ©VLG

Chris Savage · 2006-07-06 01:05

Okay,

·· I think I see what you want, but in your condensed code you're executing the same code if any of the 4 pins are high.· If that is what you want, you can do that a much easier way...Please let me know if I am on the wrong track here...

If your pins are P0-P3 then you could say:

Status···· VAR···· INA

later in your code, you could do this...

IF Status THEN
·· <do stuff here>
ENDIF

In this case, if any pin was HIGH, then the <stuff> would get executed.· Is that what you mean?

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Vern Graner · 2006-07-06 01:26

Chris Savage (Parallax) said...
Okay,

I think I see what you want, but in your condensed code you're executing the same code if any of the 4 pins are high. <snip>

Dang. Nope.. again, my bad. (I really suck at describing what I'm looking for!)

Lets see if this example is clearer:

IF PIN1 = 1 THEN
  <turn on light1>
  <play sound1>
  <move servo1 to home position>
ENDIF

IF PIN2 = 1 THEN
  <turn on light2>
  <play sound2>
  <move servo2 to home position>
ENDIF

IF PIN3 = 1 THEN
  <turn on light3>
  <play sound3>
  <move servo3 to home position>
ENDIF

The idea is to condense the above into a FOR/NEXT loop where I use a variable to represent the pin number I'm trying to sample ie:

FOR cntI = 1 to 3
  IF {pin number <cntI>} = 1 THEN
    <turn on light(cntI)>
    <play sound(cntI)>
    <move servo(cntI) to home position>
  ENDIF
NEXT

Where the command in brackets above is what I'm looking for... Any clearer?

Vern

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Vern Graner CNE/CNA/SSE    | "If the network is down, then you're
Senior Systems Engineer    | obviously incompetent so why are we
Texas Information Services | paying you? Of course,if the network
http://www.txis.com        | is up, then we obviously don't need
Austin Office 512 328-8947 | you, so why are we paying you?" ©VLG

Chris Savage · 2006-07-06 02:01

Vern,

·· I will clear my head at work tomorrow and rethink this...I think my brain just turned to mush!

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Tracy Allen · 2006-07-06 05:05

Vern,

You can address pins by index as follows:

IF IN0(cntI) = 1 THEN ...

For example IN0(5) is the same as IN5.

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Tracy Allen
www.emesystems.com

Chris Savage · 2006-07-06 14:01

Tracy,

·· I was trying to think if there was a way to condense his routine so he wouldn't have to handle one event at a time.· Since 4 pins can easily read at once it seems like it would be faster, but handling the resultant routines is what I'm not getting in this case (Sorry Vern, programmers block?).· Any ideas?

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Chris Savage
Parallax Tech Support
csavage@parallax.com

SSteve · 2006-07-07 05:10

You need to set up your output routines so that they can be addressed by the FOR/NEXT index. For example, if your lights are on pins 8-11 and you're using a PSC with servos on channels 5-8, you could write:

FOR cntI = 0 TO 3
  IF IN0(cntI) = 1 THEN
    HIGH 8 + cntI
    SEROUT PSCPin, Baud+$8000,[noparse][[/noparse]"!SC", 5 + cntI, 0, 750 & $FF, 750 >> 8, CR]
  ENDIF
NEXT

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Ryan Clarke · 2006-07-07 14:04

Treat the INS as an array, indexing off of postion 0.

It is common to do things such as:

v.bit0(d)

where d is your offset- notice I used "v", because this is just some variable that can be thought of as an array of pins. The DIRS and INS can be treated the same way.
Likewise you can use the different modifiers to just get banks/chunks (such as HIGHBYTE, LOWBYTE, LOWNIB, HIGHNIB, etc)-

Ryan

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Ryan Clarke
Parallax Tech Support

RClarke@Parallax.com

Chris Savage · 2006-07-07 14:17

Vern,

·· Okay, I think we got a little off-track there...Since there will be different code run based on a pin, and not just some other I/O pin changed you will have to use the FOR...NEXT loop, and Tracy has shown you above how to index the I/O pins in that manner.· I guess technically it won't condense the main body of the code since you will have to spell out the code for each event.· The only way it could be condensed was if each routine did the same exact thing but affected different I/O pins.· Then you could use one piece of comon code and reference the pins from there by index as well.· Sorry for the earlier confusion.· I was trying to solve this from my own perspective.

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Vern Graner · 2006-07-07 16:00

Eureka!

Thanks to you guys I have a working loop... here's a code snip I used to read a series of N.O. pushbutton switches with pull-up resistors on pins 11-15:

' ************************
' * Servo Pump           *
' *************************************************************************
FOR cntI = 1 TO 5             
  IF IN10(cntI) = 0 THEN       'the IN10+cntI value steps from pin11 to pin 15
    IF Flag(cntI) = 0 THEN     '\
      DC16Channel= cntI        ' |
      DC16State=TurnOn         ' |
       GOSUB UpdateDC16        ' |
      PSCposition = PumpStart  ' |
      PSCchannel = cntI-1      ' | Code runs when button pressed
      PSCrate = 0              ' | 
       GOSUB MoveServos        ' |
      Flag(cntI)=1             ' |
    ENDIF                      '/
  ELSE
    IF Flag(cntI) = 1 THEN     '\
      DC16Channel= cntI        ' |
      DC16State=TurnOff        ' |
       GOSUB UpdateDC16        ' |
      PSCposition = PumpStop   ' |
      PSCchannel = cntI-1      ' |
      PSCrate = 0              ' | Code runs when button released
       GOSUB MoveServos        ' |
      PaintShots=PaintShots-1  ' |
       GOSUB UpdateLED         ' |
      Flag(cntI)=0             ' |
    ENDIF                      '/
  ENDIF
NEXT

This code allows me to use the cntI variable to 1) read the pushbutton 2) send a command to the Parallax Serial Servo Controller (PSC) and 3) send a command to the DC-16. Since the DC-16 starts its channels at "1" and the PSC starts its channels at "0" I had to do a "cntI-1" to get the channels to line up, but this seems to work fine. I use the Flag (cntI) to make sure that the command is executed only one time per button press and one timer per button release (there's probably a more efficient way to do this, but I'm just hammering out test code right now, so opionions welcome!).

So, I can now hit and hold any of the buttons to get lights and servos to react in response to input! Thanks again guys!! I love these forums. Keeps me from beating my head against the wall too much..

Vern

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Vern Graner CNE/CNA/SSE    | "If the network is down, then you're
Senior Systems Engineer    | obviously incompetent so why are we
Texas Information Services | paying you? Of course,if the network
http://www.txis.com        | is up, then we obviously don't need
Austin Office 512 328-8947 | you, so why are we paying you?" ©VLG

Reading PINS in a loop?

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