USO output to an Arduino

[fw14b]

Hi,

Can anyone help me?

I use the USO output to an Arduino Mega card, to control 6 servos.

I use the following formula

S~a01~R~a02~Y~a03~W~a04~P~a05~H~a06~

My servo turning, but not with one smooth motion

Look this video http://youtu.be/InvPT-C_Oe0

Has anyone an idea to solve this problem.

Sorry for my bad english.

Regards Charles,

[sirnoname]

Seems you are reading sometimes a zero.
Remember: transfere stability is at atmel chips 90% falling with the increasing rs232 speed. A checksum is needed. At microchip it is higher.
This can also happen if your code is to slow and you do not read the 1byte buffer of the atmel chip.

[adrianovrm]

Good Morning, l having the same problemss with servos getting crazy at some moment , with my hexapod servos, getting crazy, sometimes it works, what sends a suspicious of serial errors cause without checksum , and l didnt discover how to make uso send the checksum byte ,
l know that ~a01~ is the axis value , l used 6 informations ( 25, 27 and 26 ) Vertical, longintudinal and lateral g forces to computer the translations and rotarion movements at my code and more speed, gear and rpm, gear l put in binary(8) , the left values at 16 bits. my data pacjet string is
X~A01~~A02~~A03~~A04~~A05~~A06~ , in the X-PID l saw the flowwing two functions


bool CheckChecksum() //Atmel chips have a comport error rate of 2%, so we need here a checksum
{
byte checksum=0;
for(int z=0; z < 3; z++)
{
byte val=commandbuffer[z];
checksum ^= val;
}
if(checksum==commandbuffer[3]){return true;}
return false;
}

void SerialWorker()
{
while(Serial.available())
{
if(buffercount==-1)
{
buffer = Serial.read();
if(buffer != 'X'){buffercount=-1;}else{buffercount=0;}
}
else
{
buffer = Serial.read();
commandbuffer[buffercount]=buffer;
buffercount++;
if(buffercount > 3)
{
if(CheckChecksum()==true){ParseCommand();}else{errorcount++;}
buffercount=-1;
}
}
}
}



and l notice that at the end of funcntion checkchecksum a variable computed "Checksum" is compared with the last byte received , am l right ? so , what l dont understand is how to make the USO sends this caculate byte over serial to my arduino interface, cou you aid me , guys ?
l what want to put a checksum byte for my string data packet that is now "X~A01~~A02~~A03~~A04~~A05~~A06~" how l do this ! l search at manuals l didnt found out how do it

[adrianovrm]

oops, l m blind , l think l found something like put c99 and the end of the string data packet , is that ? l will put it and see what happens, it sthere the uso explanantion, l just browse it and saw

[adrianovrm]

For we finnish this logic , there in USO it says :
"For XOR checksum use ~c99~ where 99 is a number between 0-99. This numer declares the used xor character before ~
which result the sum. "

with my data been X~A01~~A02~~A03~~A04~~A05~~A06~ , and now that we know my a01, a02, a03, a04, a05 are all 16 bits(2 BYTES) and my A06 IS 8 BITS (1 BYTES) , so we have 5*2bytes + 1byte(a06) + 1byte(X) as STX caracter, l dont use ETX(end caracter). l have 12 bytes Data Packet , right ? so my ˜c99~ string will be ~c12~ ? and my datapacket string will be X~A01~~A02~~A03~~A04~~A05~~A06~~c12~ ?

anyone with x-sim checksum experience , any help , any hope ?

[sirnoname]

X-Sim checksum code

Code: Select all

   current=current.Right(current.GetLength()-1);
   int before=atoi(current);   //length entry before ~cxx~
   int now=input.length; //input is current uso string translated before be sent
   char xorstring[5120]={0};
   if(now-before >= 0)
   {
      for(int z=0; z < before; z++)
      {
         xorstring[z]=input.buffer[now-(before-(z))];
      }
   }
   byte checksum=xorstring[0];
   if(before > 0)
   {
      for(int z=1; z < before; z++)
      {
         byte zahl=xorstring[z];
         checksum=checksum ^ zahl;
      }
   }
   char outsum=checksum;
   return outsum;

But I do not know how you can mix 8 and 16 bit output with USO.
Check the output with free comport monitor.

[adrianovrm]

Thanks , l will analyze and test and return results to you... Well l alredy work will 16 and 8 bits axis at the same datapacket, data is retrive over arduini , byte from byte, so xor is done , one by one... l not sure l understood plenty tou concer , but l think this is not a problem for me yetr.. will analyze

[adrianovrm]

L study you code and l have another doubt :

am l suppose to do some kind of DLL file for compute that before xsim sends this packet over serial, at x-sim side ?

l ask that cause l was thinking in put ~c12~ at the end of my data packet(Converter) , and x-sim autmatics sends the packet with checksum calculated, then at arduino side l should recompose the calcs to see if packet is ok .. lm a bit confuse *...

L already put ~c12~ at the end of my packet that have 13 bytes , been sent over serial each 33ms intervals.

[adrianovrm]

they dont fit equal yet, what my mistake, cant se yet

[adrianovrm]

The checksum calcalte at arduino side and value received form xsim dont fit yet