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mikedownunder

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Joined: 03/03/2016
Location: Australia
Posts: 26

Posted: 01:44pm 07 Mar 2016

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Hi All

I am new to the Back Shed forum, although not with BASIC.
Please allow me to tell you a general background about myself.

My name is Mike and I am now retired after working originally as an electrician and then for the most part as an Electronics technician.
My Basic 'training' started on a Commodore 64, which I am sure some of the older generation will remember. I then progressed to what was called in the UK a 'BBC' computer made by Acorn which was extremely popular. I was working at IBM in the UK at the time and there were over 200 'BEEB' users on site, so we had a lot of fun.
In 2002 I picked up on the now very popular and well supported Proton Basic Development Suite (PDS).
I have noticed the various different 'package' processors in the past few years (Arduino) etc., but I do like the look of the Micromite, Mainly I suppose because it uses a PIC which, of course, I am very familiar with plus I have the Pickit3 for programming when required.

Anyway I have been looking at the 'Parking Assist' program written by Geoff. Most of the commands are easily translated from one compiler to the next, however I have some questions about things that I cannot find an explanation for after looking in the MMBasic manual.
1. In the program listing what does 'DrawOption' mean and where does it come from?
2. Under 'Get selected button and take action on the button'. In the Select Case I assume that in Case2 'GetThresholds' means got to the Sub GetThresholds?
3. What is the difference between Sub, End Sub and Gosub, Return?

I want mainly to use only the part of the program which has a keypad. But I do like to understand things even if I am not using it at the time.

Thanks for being patient reading this long post and any help will be gratefully received.

Mike

Justplayin

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Joined: 31/01/2014
Location: United States
Posts: 327

Posted: 04:28pm 07 Mar 2016

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mikedownunder said Anyway I have been looking at the 'Parking Assist' program written by Geoff. Most of the commands are easily translated from one compiler to the next, however I have some questions about things that I cannot find an explanation for after looking in the MMBasic manual.
1. In the program listing what does 'DrawOption' mean and where does it come from?
2. Under 'Get selected button and take action on the button'. In the Select Case I assume that in Case2 'GetThresholds' means got to the Sub GetThresholds?
3. What is the difference between Sub, End Sub and Gosub, Return?

Hi Mike and welcome to the forum! I can't seem to find the 'Parking Assist' program you are referring to at the moment, but I believe you have correctly figured out that 'DrawOption' and 'GetThresholds' are both SUBS. SUB are very much like using GOSUB but with some advantages. They allow you to create your own commands. You may pass them arguments if you wish and they have access to all the other variables of your programs. However, you can also localize the variables within the SUB to prevent conflicts with existing variables in your program. The 'END SUB' quits the SUB and deletes all the localized variables then returns control back to where the SUB was called from.

'Fifth power of number, a totally pointless program
For i = 1 To 10
Fifth(i)
Next i
Print x, y
End

Sub Fifth(x)
Local i,y
y=1
For i = 1 To 5
y = y*x
Next i
Print y
End Sub

If you run this program in the program it will print out the following, and notice X and y are 0. x and y only exist when the SUB is being executed. Also, notice I used the variable i in the main program and the SUB at the same time and it does not cause a problem because i in the SUB is Local to the SUB only.

1
32
243
1024
3125
7776
16807
32768
59049
100000
0 0

Does that help... or did I confuse you more?

--Curtis
Edited by Justplayin 2016-03-09

I am not a Mad Scientist... It makes me happy inventing new ways to take over the world!!

paceman
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Joined: 07/10/2011
Location: Australia
Posts: 1329

Posted: 09:14pm 07 Mar 2016

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@mikedownunder
Hello Mike, welcome to the forum.

@Just playin
Hi Curtis - the Parking Assist program is part of a project Geoff described in the current March issue of Silicon Chip (SC) magazine. The program is available from SC but I've just had a look at Geoff's site and I can't see it there so I guess he hasn't generally released it yet. If you PM Geoff I think he'd be happy to send you a link.

Greg

WhiteWizzard
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Joined: 05/04/2013
Location: United Kingdom
Posts: 2934

Posted: 09:23pm 07 Mar 2016

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@Justplayin

A very good example - and very well explained

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6270

Posted: 10:56am 08 Mar 2016

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The code is available from silicon chip magazine.
http://www.siliconchip.com.au/Shop/6/3342

Jim

VK7JH
MMedit

mikedownunder

Newbie

Joined: 03/03/2016
Location: Australia
Posts: 26

Posted: 07:28pm 08 Mar 2016

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Hi All
This is the file from SC.
2016-03-09_052333_2016-01-23_080736_ParkingAssist.zip

Thanks for the info on Sub's it certainly covered the detail.
However my other question remains unanswered, namely.
1. In the program listing what does 'DrawOption' mean and where does it come from?
In the attached program this is listed on lines 127 - 129, under Sub GetOptions.
There is no variable or array declared for DrawOption, so how come I don't get a syntax error?
I can see what the action does, but as I said I like to know the whole story and why things are done a certain way.

Thanks again for any help.

Mike

disco4now

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Joined: 18/12/2014
Location: Australia
Posts: 1000

Posted: 07:43pm 08 Mar 2016

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I think you will find the SUB DrawOption in the code there somewhere.
It looks like this.
Regards
Gerry

' draw a single option
Sub DrawOption n As Integer, colour As Integer, caption As String, vert As Integer, var As Float, units As String
Const btn_width = 80'120
Const fonth = MM.FontHeight * 2
Const space = 4
Text MM.HRes/2, vert, caption, CT, 2, 1, colour
If var <> -1 Then Text MM.HRes/2 - 20, vert + fonth + space, Str$(var) + " " + units, RT, 2, 1, colour
key_coord(n,0) = 220'MM.HRes/2 + 20 'x
key_coord(n,1) = vert + fonth + space/2
key_coord(n,2) = btn_width
key_coord(n,3) = fonth + space
key_coord(n,4) = RGB(cyan)
key_caption(n) = "SET"
DrawButton n, 0
End Sub

Latest F4 Latest H7 FotS

mikedownunder

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Joined: 03/03/2016
Location: Australia
Posts: 26

Posted: 10:11pm 08 Mar 2016

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Oh my, I feel such an idiot

Thanks Gerry. I guess it's where I am used to using Gosub's and not recognising the SUB's.

Hopefully I can start to understand what's going on a bit better now.

So thanks again everybody for the help. I'll probably be back with other questions soon.

Mike

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