[Tinyos-help] Error when receiving matrix values

Michael Schippling schip at santafe.edu
Sat Apr 10 14:19:45 PDT 2010


Also be aware that Java has no unsigned ints
so you have to be especially overindulgent
when converting them from the TOS_Msg into
println()able elements, e.g.:

	// ToByte -- TOS to Java
	// Unsigned convert buffer at 'start'
	//  from a byte to Java int, without sign
	public static int tb( byte[] buf, int start )
	{
		return ( buf[start] & 0xff );
	}

Without the "& 0xff" the sign bit of the byte will
be extended into the full int return value.

MS

Sindra Dk wrote:
> thanks for your answer, i will try then i tell you if it works or not !!
> 
> Sindra
> 
> ------------------------------------------------------------------------
> From: sapojnik at gmail.com
> Date: Sat, 10 Apr 2010 23:50:42 +0300
> Subject: Re: [Tinyos-help] Error when receiving matrix values
> To: asma_192 at live.fr
> CC: tinyos-help at millennium.berkeley.edu
> 
> Although I still don't see the whole picture, I think that your problem 
> is that you are using 8 bits for every element.
> Now either it's 0:225 or -128 to +127.
> So you probably have declared the struct that you send as int8_t[][] array.
> Try to declare it as int16_t and don't forget that the default message 
> payload size is 28 bytes.
> 
> Arik
> 
> 
> On Sat, Apr 10, 2010 at 23:39, Sindra Dk <asma_192 at live.fr 
> <mailto:asma_192 at live.fr>> wrote:
> 
>     Hi all,
>     im working on copression algorithm and i use TinyOS 2.x
>     i send an image from PC to mote i decompressed it then when i resend
>     it to PC
>     i get an error on its pixels value:
> 
>     Original matrix
>     uint8_t A[i][j]={{172,132,4,39},{23,127,5,4},{44,7,6,9},{77,211,19,5}};
> 
>     $ java TestSerial -comm serial at com5:telos
>     Sending packet 0
>     serial at com5:115200: resynchronising
>     Sending packet 1
>     Received packet sequence number 1
>     l'affichage  est:-29  (wrong value)               
>     l'affichage  est:26
>     l'affichage  est:-32
>     l'affichage  est:-17
>     l'affichage  est:-87  (wrong value)
>     l'affichage  est:19
>     l'affichage  est:-48
>     l'affichage  est:5
>     l'affichage  est:77
>     l'affichage  est:17
>     l'affichage  est:72
>     l'affichage  est:-18
>     l'affichage  est:-118
>     l'affichage  est:-4
>     l'affichage  est:85
>     l'affichage  est:-8
> 
>     ***************************************
>     Display matrix as C is: 
>     227   (this is a true value)
>     26
>     -32
>     -17
>     169.5  (this is a true value)
>     19.5
>     -48.5
>     5.5
>     77
>     17
>     72
>     -18
>     -118.5
>     -4.5
>     85.5
>     -8.5
>     i don't know why i can't display values higher than 127!!!
>     can any one help me please? and thanks in advance.
>     Ragards,
>     Sindra
> 
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> 
> 
> 
> -- 
> Best Regards,
> Arik Sapojnik
> 
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