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Flash
Joined: 03 Feb 2006
Posts: 153
Location: EU
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 Posted: Mon Jan 14, 2019 3:12 pm Post subject: Receiving zero(0) bytes |
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Is there some way of receiving (UART) zero bytes (e.g. 0,0,0,0), because Ischarwaiting=0 if all bytes are zero(0), only if one is >0 (0,0,0,1) then it worrks fine (it detects that something is received). Problem is because slave send some empty bytes data which can't be changed.
Thanks
(BASCOM-AVR version : 2.0.8.1 )
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A clever person solves a problem. A wise person avoids it. Albert Einstein |
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i.dobson
Joined: 05 Jan 2006
Posts: 1570
Location: Basel, Switzerland
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| Posted: Mon Jan 14, 2019 4:18 pm Post subject: |
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Hi,
Maybe a Do Loop while ISCHARWAITING. Something like:-
| Code: |
While Ischarwaiting(#2) = 1 'loop through data
Rfid_char = Inkey(#2) 'Get 1 byte
If Rfid_char = 2 Then 'Chr 2 - Start of MSG
Rfid_ptr = 0 'Reset pointer
Else
Incr Rfid_ptr 'Move to next byte
Rfid_array_local(rfid_ptr) = Rfid_char 'Save char to array
End If
If Rfid_ptr >= 12 Then ' correct length
Rfid_have_buffer = 1 'tell user space
Rfid_ptr = 0 'Reset buffer pointer
Exit While 'Move on
End If
Wend
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In this example CHR(2) is the start of a message the message is always 12 bytes long and the data lands in a Byte array (Rfid_array_local). Note I'm using buffered serial i/o so this routine doesn't need to be called that often.
Regards
Ian Dobson
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MWS
Joined: 22 Aug 2009
Posts: 2262
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| Posted: Mon Jan 14, 2019 5:31 pm Post subject: Re: Receiving zero(0) bytes |
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| Flash wrote: | | because Ischarwaiting=0 if all bytes are zero(0) |
Your statement is wrong.
Ischarwaiting() returns an 1 for a byte received, doesn't matter of the byte's value.
Your code - which you do not show - is flawed. |
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Duval JP
Joined: 22 Jun 2004
Posts: 1161
Location: France
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| Posted: Mon Jan 14, 2019 6:22 pm Post subject: |
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see the help about null character
I suppose you know but ...
null ascii 0 is different of "0" chr ( 48 )
Help said
"you can send and receive both with While the Inkey() will get the character from the HW UART when there is a character in the buffer, it will return a zero when the character is zero. This makes it unusable to work with binary data that might contain the value 0."
Ischarwaiting()
"While the Inkey() will get the character from the HW UART when there is a character in the buffer, it will return a zero when the character is zero. This makes it unusable to work with binary data that might contain the value 0.
With IsCharWaiting() you can first check for the presence of a character and when the function returns 1, you can retrieve the character with Inkey or Waitkey."
so ischarwaiting return 1 when you send it a null but inkey see nothing.
so please send us a your code
JP
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Flash
Joined: 03 Feb 2006
Posts: 153
Location: EU
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| Posted: Mon Jan 14, 2019 7:29 pm Post subject: Re: Receiving zero(0) bytes |
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| MWS wrote: | | Flash wrote: | | because Ischarwaiting=0 if all bytes are zero(0) |
Your statement is wrong.
Ischarwaiting() returns an 1 for a byte received, doesn't matter of the byte's value.
Your code - which you do not show - is flawed. |
This is not a code, I know that Ischarwaiting() returns an 1, here is question why it don't return 1 when I received e.g. three bytes in a row and all of this three have value 0x00, shouldn't Ischarwaiting() recognize this bytes with value=0?
This is the simple code (AT90CAN):
| Code: |
Config Com2 = Dummy , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0
Open "COM2:" For Binary As #2
Config Serialin1 = Buffered , Size = 100
'Slave send some bytes (3 or more) with 0x00 values (I can see them on logic analyzer) on COM2 UART - Ischarwaiting(#2) = 0
If Ischarwaiting(#2) = 1 Then 'loop through data
'do something
Else
'do something
End if
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When is one of the received byte with value >0 (e.g. 0x01) then is all ok -Ischarwaiting(#2) = 1. I don't need to use inkey, waitkey, inputbin etc. only confirmation of receipt.
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MWS
Joined: 22 Aug 2009
Posts: 2262
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| Posted: Mon Jan 14, 2019 8:22 pm Post subject: Re: Receiving zero(0) bytes |
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| Flash wrote: | | This is not a code, |
Yes, you're right, these are only unrelated lines, but no code which would allow to tackle the issue.
| Quote: | | I don't need to use inkey, waitkey, inputbin etc. only confirmation of receipt. |
Without use of any of these, or similar commands the input buffer won't be emptied and no incoming data is read..
Makes no sense.
If you expect help, post a compilable example which shows the problem. |
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Flash
Joined: 03 Feb 2006
Posts: 153
Location: EU
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| Posted: Tue Jan 15, 2019 10:11 am Post subject: |
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Adding some time for UART to setup after Print command solved problem.
| Code: | Config Com2 = Dummy , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0
Open "COM2:" For Binary As #2
Config Serialin1 = Buffered , Size = 100
Printbin #2, command_byte 'for slave
'Slave send some bytes (3 or more) with 0x00 values (I can see them on logic analyzer) on COM2 UART - Ischarwaiting(#2) = 0
Waitus 200 'UART need some time for setup
If Ischarwaiting(#2) = 1 Then 'loop through data
'do something
Else
'do something
End if |
Tnx all
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