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[SOLVED] 8051, need help on UART receiving

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bitsurfer

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Hello,
I need help for 8051 serial communication with computer.
While sending strings to computer goes OK I have serious problem with receiving.
Mostly because I don't understand this part well.

This is critical part of my 8051 C code:

Code: 
         SCON = 0x50;
         TMOD = 0x20; //timer 1, mode 2, 8-bit reload
         TH1  = 0xFD; //reload value for 9600 baud
         TR1  = 1;
         TI   = 1;

again:
		while(RI!=1) 
		{;} 
        		P1 = SBUF; //send to port with led's to see what happens
        		RI = 0;
                      // here is key check for terminate receiving...
                      goto again;

I send from computer numbers from 0 to 15 as strings.
This is VB.NET code:

Code: 
        For t As Integer = 0 To 15
            Application.DoEvents()
            Form1.sPort.Write(CStr(t)) 'it have to be a string?
            Sleep(3000)
        Next

What happens?
Bytes arrived to SBUF with values 0-7 and beeing showed on first 4 leds of port P1.
When commes a number greater than 9 (say "10") then two bytes arrives.
But I need to send from computer numbers from 0 to 255 to be visible on all bytes of P1.

What should I do to achieve this?
 

sent asccii via the port.
Code: 
        For t As char = 0 To 15
            Application.DoEvents()
            Form1.sPort.Write(t) 'it have to be a string?
            Sleep(3000)
        Next
 

That gives a same result. VB.NET convert number to char anyway by himself.
Why I get showed on P1 only 4 bit numbers?
 

I do sent "a".
And get 10000110 on P1.
For "A" I get 10000010.
 

This is problem.
If I send 255 then port goes to 10101100!
First four bits is 5, and I think that UART receives more than one byte but passes too fast to see.
 

dim b as string
For t As char = 0 To 255
b = chr (t)
Application.DoEvents()
Form1.sPort.Write(b) 'it have to be a string?
Sleep(3000)
Next t
 
Last edited:
I tried.
Please note that "data" is reserved word in keil C so I have to change that in order to compile, right?
After all result is a same.
I finishes with 10101100 on P1.

But led's shortly flashes what says that more than one byte arrives.
 

Hm, Magvitron,
The best what I can get from your suggestions is this:

Code: 
        Dim b As String
        For t As Byte = 0 To 255
            b = Chr(t)
            Application.DoEvents()
            Form1.sPort.Write(b)
            Sleep(100)
        Next t

This counts to 127 (7bits) and for other 127 (to 255) nothing happens on P1.

EDIT:
A bit shorter, also work's up to 127.
Code: 
        For t As Integer = 0 To 255
            Form1.sPort.Write(Chr(t))
        Next t

I would like to know why P1 dont show values from 128-255...
 
Last edited:

Well, solution is really ODD, but I find it on the net now...

If someone ever will need to send integers 0 to 255 to UART through VB.NET:
Code: 
Dim r As Integer = 255  'your integer

        Form1.sPort.Encoding = System.Text.Encoding.GetEncoding(1250)
        Form1.sPort.Write(Chr(r))

Magvitron, thanks for helping...
 

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