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I'm having some problems with received checksum when X > 255

Pixy Software
#1

Hello,
First, I like pixy very much. I’m obsesed with it. Thanks!.
I’m receiving pixy data using uart interface at 38400 bauds. I’m using received checksum data in order to validate object block information. I think there is some problem in object block checksum. When Pixy sends object information with x > 255 (x.MSB > 0), received checksum is wrong.
I’m using firmware-1.0.2beta.
I’m attaching an excel file to beter explain problem.
Thank you!

#2

Hi Marceliano,

Thanks for the heads up! I’ll have someone look in to this.

Scott

#3

Marceliano,

What type of device are you connecting your Pixy to?

Thanks,
John

#4

I suspect there’s something going on with the way you’re calculating the checksum. The checksum is the sum of the 16-bit values in the object block and is a 16-bit value itself. (don’t treat the numbers as two 8-bit values)

#5

Hello,
You are right!. I was calculating the checksum adding received 8 bit bytes. I’m correcting it.
Thank you Rich.

#6

To John Leimon:
Hello John,
I’m using a custom made board with a Pic33 micro.