TheBackShed.com

Forum Index : Microcontroller and PC projects : Reading AIN and display in Number Box 2 decimal places

Author

Message

envirotronics
Newbie

Joined: 18/02/2016
Location: Australia
Posts: 23

Posted: 07:13am 01 Jun 2021

Copy link to clipboard

Print this post

Hi,
I need to read and Analog port and display the reading in a number box limiting the reading to 2 decimal places. Cant seem to do it. Can anyone assist? Current reading displays at least 6 decimal places.

Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 7937

Posted: 07:28am 01 Jun 2021

Copy link to clipboard

Print this post

A good starting point is STR$(). It's a pretty flexible function. :)

STR$(1.2345678,,2) will display 2 characters after the decimal place i.e. 1.23. Anything after that is truncated - it won't round up 1.239 to 1.24.

Also look at FORMAT$(nbr [,fmt$]). This can use a fmt$ to format nbr into a particular format. Maybe not exactly what you are looking for, but it might come in useful for a display.

Here's an old function from an old TRS-80 book. This rounds to 2 decimal places correctly. :) Never throw old computer books out.

Function round(n)
round=Fix((Fix(n*1000)+Sgn(n)*5)/10)/100
End Function
Edited 2021-06-01 18:01 by Mixtel90

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

envirotronics
Newbie

Joined: 18/02/2016
Location: Australia
Posts: 23

Posted: 08:41am 01 Jun 2021

Copy link to clipboard

Print this post

Thanks Mick
I was doing something like that but no go.
See code below
Any clues"
'tests AIN straight to Gauge and number ox'

cls
Const frm_big2=82
Const c_hi2=34, c_lo2=35,c_bot2=37
nbr_hi2=31
GUI Caption c_hi2, "SET PRESSURE PSI",285,70, "LT",RGB(red)
Font 4: GUI Frame frm_big2,"",0,0,790,470,RGB (green)
GUI gauge #32,100,380,90,RGB(green),0,0,3.3,2,"LEAK PSI",RGB(yellow),1.5 ,RGB(blue),2.5,RGB(red)
GUI Numberbox nbr_hi2,310,100,200,MM.FontHeight+40,RGB(yellow),RGB(64,64,64)
setpin 59,dout
setpin 14, ain
READVOLTS:
CtrlVal (#32) =(pin (14))
CtrlVal (#31) =Str$(pin(14),,2)
pause 1000

goto READVOLTS

Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 7937

Posted: 09:20am 01 Jun 2021

Copy link to clipboard

Print this post

I've nothing to run the GUI commands on yet. I've not got round to wiring a LCD display onto my F4. It's a "tomorrow" job ...

Your prog looks ok to my unpracticed eye. You could probably use CtrVal(#31)=round(Pin(14)) if you wanted to try the function I mentioned.

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

matherp
Guru

Joined: 11/12/2012
Location: United Kingdom
Posts: 10310

Posted: 10:08am 01 Jun 2021

Copy link to clipboard

Print this post

Try

CtrlVal (#31) =Str$(pin(14),2)

Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 7937

Posted: 10:29am 01 Jun 2021

Copy link to clipboard

Print this post

That'll work, Peter, but it won't round to 2 decimal places, it's a truncation.
So 1.234 and 1.235 would both give 1.23.
The function I showed will automatically round up, so 1.234 gives 1.23 and 1.235 gives 1.24.

Of course, it may not matter. :)

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

disco4now

Guru

Joined: 18/12/2014
Location: Australia
Posts: 1003

Posted: 11:15am 01 Jun 2021

Copy link to clipboard

Print this post

v=CINT(100*pin(14))
CtrlVal (#31) =str$(v/100,2,2)

Latest F4 Latest H7 FotS

envirotronics
Newbie

Joined: 18/02/2016
Location: Australia
Posts: 23

Posted: 12:25pm 01 Jun 2021

Copy link to clipboard

Print this post

Mixtel90 said That'll work, Peter, but it won't round to 2 decimal places, it's a truncation.
So 1.234 and 1.235 would both give 1.23.
The function I showed will automatically round up, so 1.234 gives 1.23 and 1.235 gives 1.24.

Of course, it may not matter. :)

Hi,
I jhave tried that and error is "Expected a number"

envirotronics
Newbie

Joined: 18/02/2016
Location: Australia
Posts: 23

Posted: 12:27pm 01 Jun 2021

Copy link to clipboard

Print this post

disco4now said

v=CINT(100*pin(14))
CtrlVal (#31) =str$(v/100,2,2)

Thanks Guru, I will try that tomorrow

envirotronics
Newbie

Joined: 18/02/2016
Location: Australia
Posts: 23

Posted: 12:30pm 01 Jun 2021

Copy link to clipboard

Print this post

envirotronics said

disco4now said

v=CINT(100*pin(14))
CtrlVal (#31) =str$(v/100,2,2)

Thanks Guru, I will try that tomorrow

I tried tat and it comes up with ERROR: "expected a number"

Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3292

Posted: 01:48pm 01 Jun 2021

Copy link to clipboard

Print this post

It is not properly specified in the manual (which I will fix) but all controls expect to be assigned a number (float or integer) except Frame, Caption, Display Box, Text Box and Format Box which expect a string.

So you should use:

v=Cint(100*Pin(14))
CtrlVal(#31) = Val(Str$(v/100,2,2))

Although this is simpler:

CtrlVal(#31) = Cint(100*Pin(14))/100

Geoff

Geoff Graham - http://geoffg.net

Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 7937

Posted: 01:56pm 01 Jun 2021

Copy link to clipboard

Print this post

Yep - didn't spot that. It needs changing to:

CtrVal = Val(Str$(Pin(14),2))

Str$(Pin(14),2) is returning a formatted string, of course, so Val() will convert it back into a number.

It's the same in the other suggestions.

CtrVal = round(Pin(14))
with
Function round()

would get the analogue value from Pin14 and round it without any string conversions.

There's always more than one way to skin a cat. :)
Edited 2021-06-01 23:58 by Mixtel90

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 09:37pm 01 Jun 2021

Copy link to clipboard

Print this post

Just for the record,
STR$() does round. What happens with 0.5 is less certain but anything else will round.

print str$(1.23456,2,2)
print str$(1.235,2,2)
print str$(1.2356,2,2)
print str$(1.245,2,2)

Jim

VK7JH
MMedit

envirotronics
Newbie

Joined: 18/02/2016
Location: Australia
Posts: 23

Posted: 10:01pm 01 Jun 2021

Copy link to clipboard

Print this post

Geoffg said It is not properly specified in the manual (which I will fix) but all controls expect to be assigned a number (float or integer) except Frame, Caption, Display Box, Text Box and Format Box which expect a string.

So you should use:

v=Cint(100*Pin(14))
CtrlVal(#31) = Val(Str$(v/100,2,2))

Although this is simpler:

CtrlVal(#31) = Cint(100*Pin(14))/100

Geoff

Thanks Geoff.
Works well
Graham

Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 7937

Posted: 07:46am 02 Jun 2021

Copy link to clipboard

Print this post

TassyJim said

Just for the record,
STR$() does round. What happens with 0.5 is less certain but anything else will round.

print str$(1.23456,2,2)
print str$(1.235,2,2)
print str$(1.2356,2,2)
print str$(1.245,2,2)

Jim

I wonder where I screwed up when I tried it? Weird....
Thanks, Jim, I stand corrected and I promise to be more diligent in my testing in future (but then, we all say that!). :)

1.235 doesn't round up, 1.236 does.

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

Print this page

To reply to this topic, you need to log in.