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Zvoc47
Joined: 02 Apr 2015
Posts: 21
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 Posted: Sat Apr 11, 2015 11:17 pm Post subject: Backspacing on input inputs backspaces! |
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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 ) |
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bzijlstra
Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands
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| Posted: Sat Apr 11, 2015 11:55 pm Post subject: Search for inkey(), Waitkey, ischarwaiting and $timeout |
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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 |
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Paulvk
Joined: 28 Jul 2006
Posts: 1257
Location: SYDNEY
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| Posted: Sun Apr 12, 2015 12:20 am Post subject: |
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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 |
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Zvoc47
Joined: 02 Apr 2015
Posts: 21
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| Posted: Sun Apr 12, 2015 1:09 am Post subject: |
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| But which file is it? |
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Paulvk
Joined: 28 Jul 2006
Posts: 1257
Location: SYDNEY
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| Posted: Sun Apr 12, 2015 10:30 am Post subject: |
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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
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Zvoc47
Joined: 02 Apr 2015
Posts: 21
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| Posted: Sun Apr 12, 2015 8:24 pm Post subject: |
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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. |
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Paulvk
Joined: 28 Jul 2006
Posts: 1257
Location: SYDNEY
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| Posted: Mon Apr 13, 2015 9:45 am Post subject: |
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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 |
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Zvoc47
Joined: 02 Apr 2015
Posts: 21
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| Posted: Mon Apr 13, 2015 2:54 pm Post subject: |
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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 
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] |
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bzijlstra
Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands
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| Posted: Tue Apr 14, 2015 1:08 am Post subject: pll |
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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 |
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Zvoc47
Joined: 02 Apr 2015
Posts: 21
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| Posted: Fri Apr 17, 2015 3:46 pm Post subject: |
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| I don't understand. I don't think I'm using PLL. I have a 32MHz crystal. Is there a way to check this? |
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