Forum - MCS Electronics

 

FAQFAQ SearchSearch RegisterRegister Log inLog in

Backspacing on input inputs backspaces!

 
Post new topic   Reply to topic    www.mcselec.com Forum Index -> BASCOM-AVR
View previous topic :: View next topic  
Author Message
Zvoc47

Bascom Member



Joined: 02 Apr 2015
Posts: 21

PostPosted: Sat Apr 11, 2015 11:17 pm    Post subject: Backspacing on input inputs backspaces! Reply with quote

When I try to input an 8 character long string and use backspaces, the backspaces actually enter the array! Instead, they should remove the last character in the input buffer, but why don't they?
Here's my code
Code:
Dim ime As String * 8
Input ime
Print ime

On the terminal, when you enter ABCD(backspace)(backspace)EFGH, the input doesn't let you enter GH because the buffer is filled with the backspaces. However, the output is ABEF.

Is there a way to go around this?

(BASCOM-AVR version : 2.0.7.8 )
Back to top
View user's profile
bzijlstra

Bascom Ambassador



Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands

netherlands.gif
PostPosted: Sat Apr 11, 2015 11:55 pm    Post subject: Search for inkey(), Waitkey, ischarwaiting and $timeout Reply with quote

Search in the help for inkey()

Action

Returns the ASCII value of the first character in the serial input buffer.

Syntax

var = INKEY()

var = INKEY(#channel)

Remarks
Var

Byte, Integer, Word, Long or String variable.

Channel

A constant number that identifies the opened channel if software UART mode

If there is no character waiting, a zero will be returned.

Use the IsCharWaiting() function to check if there is a byte waiting.

The INKEY routine can be used when you have a RS-232 interface on your uP.

The RS-232 interface can be connected to a comport of your computer.

As zero(0) will be returned when no character is waiting, the usage is limited when the value of 0 is used in the serial transmission. You can not make a difference between a byte with the value 0 and the case where no data is available.

In that case you can use IsCharwaiting to deterimine if there is a byte waiting.

See also

WAITKEY , ISCHARWAITING , $TIMEOUT

Have fun
Ben Zijlstra
Back to top
View user's profile Visit poster's website
Paulvk

Bascom Member



Joined: 28 Jul 2006
Posts: 1192
Location: SYDNEY

australia.gif
PostPosted: Sun Apr 12, 2015 12:20 am    Post subject: Reply with quote

Hello Zvoc47

If you are entering characters via a computer and terminal program
and want the backspace to remove characters in a buffer in the AVR
you need to write a sub that does this
I found that more than one value was sent by different terminal programs.
The good news is I have already done all the work.
In the blog section http://www.mcselec.com/index2.php?option=com_forum&Itemid=59&page=viewforum&f=19
You will find my Web Servers
The code for a working command prompt with backspace is there as a separate sub that you can use in your own program.

Regards Paul
Back to top
View user's profile
Zvoc47

Bascom Member



Joined: 02 Apr 2015
Posts: 21

PostPosted: Sun Apr 12, 2015 1:09 am    Post subject: Reply with quote

But which file is it?
Back to top
View user's profile
Paulvk

Bascom Member



Joined: 28 Jul 2006
Posts: 1192
Location: SYDNEY

australia.gif
PostPosted: Sun Apr 12, 2015 10:30 am    Post subject: Reply with quote

Ok I cut out the code so you can see it
now it depends which terminal program you use as to which character is backspace
some I have found send more than one character
here it is chr 8
so just attach an LCD to the avr and print the character number to the lcd
this is what I did to see what was received in the buffer

Uartrx is the sub that decides what to do with the data sent


Regards Paul

Code:


'-------------------------------------
'--This will create a command line prompt so that
'--we can use rs232 to communicate with the AVR

 Charwaiting = Ischarwaiting()

   If Charwaiting = 1 Then
      Uart_char = Inkey()
      'Print Uart_char;

    If Len(uart_command) > 30 Then

    Uart_char = 13     'this is the Enter  key

    End If


     Select Case Uart_char

     Case 27                                                'the escape character to abort entry

         Print Prompt;                                      'Using a constant will let us change the prompt
         Uart_command = ""

    '--- here we backspace characters in the buffer

      Case 8

        Print Chr(8);                                       'the backspace

        Karpos = Len(uart_command)                          'find the length of Uart_command
        If Karpos > 0 Then                                  'if it has characters

             Delchar Uart_command , Karpos                  'delete last character

        End If


      Case 13

         Call Uartrx

         Print Prompt;                                      'Using a constant will let us change the prompt
         Uart_command = ""

      Case Else

         Uart_command = Uart_command + Chr(uart_char)       'this adds each character to the string
         Print Chr(uart_char);                              'this echos the commad back to the screen
                                                             'so the user can see what they have typed


     End Select

   End If

 
Back to top
View user's profile
Zvoc47

Bascom Member



Joined: 02 Apr 2015
Posts: 21

PostPosted: Sun Apr 12, 2015 8:24 pm    Post subject: Reply with quote

Thanks.
If uart_command is long 78 characters, will
Code:
Uart_command = Uart_command + Chr(uart_char)
use up 157 bytes? I need to be cautious with the space I use and I must know how long the frame should be.
Back to top
View user's profile
Paulvk

Bascom Member



Joined: 28 Jul 2006
Posts: 1192
Location: SYDNEY

australia.gif
PostPosted: Mon Apr 13, 2015 9:45 am    Post subject: Reply with quote

You would need one byte for every character then there is another byte at the end of the string.

I see you are using Local variables this is good as it saves ram but remember they do not get cleared.

I use split to search strings it can replace mid() in many cases but it needs a global array
It has saved me a lot of code.

If you use a mega128 you should not run out of ram I have variables that are 1000 characters in my web servers
and still have spare ram I run out of flash before ram.

Also I use IsCharwaiting so that I do not stop and wait.

Regards Paul
Back to top
View user's profile
Zvoc47

Bascom Member



Joined: 02 Apr 2015
Posts: 21

PostPosted: Mon Apr 13, 2015 2:54 pm    Post subject: Reply with quote

Don't worry. They don't need automatic clearing. And as much as I see, they are "popped" from the stack in such a way when the function is re-entered, they are overwritten with new ones. This means no memory leak Smile

This is my code:
Code:
$regfile = "xm128a1def.dat"
$Crystal=32000000
$hwstack=4160 ' This is because I put SPH to $2F instead of $3F
$swstack=16
$framesize=32
$baud = 115200
Config Serialin = Buffered , Size = 80
Config Serialout = Buffered , Size = 254

Declare Sub UsartInput(byref Target As String, byval MaxChars As Integer)

Enable interrupts

Dim ime As String * 8

SPH=$2F

Do
Call UsartInput(ime,8)
Print ime
Loop until lcase(ime)="over"

do
print "Over!"
Waitms 100
loop

End


Sub UsartInput(byref Target As String, byval MaxChars As Integer)
   Local A As Byte
   Local Index As Integer
   Local WhiteSpace As Byte
   Local I As Byte
   InputAgain:
   Target=""
   Index=0
   WhiteSpace=0
   Do
   A=WaitKey()
   If A=8 Then
      If Index>0 Then
         Print Chr(8);" ";Chr(8);
         Decr Index
         Target=left(Target,Index)
      End if
   Else
      If A>31 And A<127 Then
         If Index<MaxChars Then
            Incr Index
            Target=Target+Chr(A)
            Print Chr(A);
         End If
      End If
   End If
   Loop Until A=13
   WhiteSpace=1
   If Index>0 Then
      For I=1 To Index
         If Mid(Target,I,1)<>" " Then WhiteSpace=0
      Next I
   End If
   If WhiteSpace=1 Then
      Print ""
      Goto InputAgain
   End If
   Print ""
End Sub


And I'm using ATXMEGA128A1.
And the best of all, the code works!
Except for waitms 100 waiting 1.5 seconds.[/code]
Back to top
View user's profile
bzijlstra

Bascom Ambassador



Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands

netherlands.gif
PostPosted: Tue Apr 14, 2015 1:08 am    Post subject: pll Reply with quote

For the wait problem do a search on PLL.
in the wiki, the 7 inch display is driven bij an Atxmega128a1 and at the top of the program PLL settings.

Have fun
Ben Zijlstra
Back to top
View user's profile Visit poster's website
Zvoc47

Bascom Member



Joined: 02 Apr 2015
Posts: 21

PostPosted: Fri Apr 17, 2015 3:46 pm    Post subject: Reply with quote

I don't understand. I don't think I'm using PLL. I have a 32MHz crystal. Is there a way to check this?
Back to top
View user's profile
Display posts from previous:   
Post new topic   Reply to topic    www.mcselec.com Forum Index -> BASCOM-AVR All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum