set PID speed

[fausto.tromba]

I tried to set the PID speed with the method SetM1Velocity(address, p,i,d,qpps)
it looks like that p, i, d and qpps must be an integer otherwise there is the following error:

Code: Select all

pi@raspberrypi:~/Documents/MCP236_py3/TestPrograms $ python3 roboclawPIDspeedpy.py 
'MCP236 2x30A v1.1.8\n'
Traceback (most recent call last):
  File "roboclawPIDspeedpy.py", line 25, in <module>
    rc.SetM1VelocityPID(address,p,i,d,qpps)
  File "/home/pi/Documents/MCP236_py3/TestPrograms/roboclaw_3.py", line 765, in SetM1VelocityPID
    return self._write4444(address,self.Cmd.SETM1PID,d*65536,p*65536,i*65536,qpps)
  File "/home/pi/Documents/MCP236_py3/TestPrograms/roboclaw_3.py", line 534, in _write4444
    self._writelong(val1)
  File "/home/pi/Documents/MCP236_py3/TestPrograms/roboclaw_3.py", line 199, in _writelong
    self._writebyte((val>>24)&0xFF)
TypeError: unsupported operand type(s) for >>: 'float' and 'int'

at the page 65 of the user manual explain that for a value bigger than a byte, it must be broken.
In BasicMicroStudio is possible to set a pid with a floating point



how can I do by serrial command?
Thanks in advance

[Basicmicro Support]

QPPS is an integer. P,I and D can be any positive values.

Motion studio converts the real numbers in to the proper format for the SetPID commands.

Make sure you have the latest version of Motion Studio.

[fausto.tromba]

I was speaking about SetM1Velocity(address, p,i,d,qpps) python method.
it does not work, when I pass not an integer, but a float. For example p=7.2.
Ho can I set by serial port a float (P=7.2) ?

[Basicmicro Support]

The packet serial commands expect integer values. They are calculated as fixed point numbers. You have to do the math. For Velocity PID values they are 16:16 fixed point numbers so you have to multiply your 7.2 * 65536. Convert to an Integer and then give it to the SetM1VelocityPID command. For the SetM#PositionPID command they are 22:10 fixed point so multiply by 2048.

[fausto.tromba]

Code: Select all

def line2int(line):
	line = line.strip()
	#print(line)
	l1,l2 = line.split(":=")
	return l2
	

def ReadFile():
	f=open("/home/pi/Documents/MCP236_py3/PRG/PIDs.txt")
	lines=f.readlines()
	f.close()
	mpPar = map(line2int,lines)
	prm = list(mpPar)
	
	P = float(prm[0])
	i_P = int(65536*P)
	
	I = float(prm[1])
	i_I = int(65536*I)
	
	D = float(prm[2])
	i_D = int(65536*D)
	Qpps = int(prm[3])
	i_Qpps = int(65536*Qpps)
	return (i_P,i_I,i_D,i_Qpps)
	



if __name__ == "__main__":
	rc = Roboclaw("/dev/ttyS0",38400)
	rc.Open()
	
	#Get version string
	address = 0x80
	version = rc.ReadVersion(address)
	if version[0]==False:
		print ("GETVERSION Failed")
	else:
		print (repr(version[1]))
	
	#Read file PIDs.txt
	p,i,d,qpps = ReadFile()
	print(p,i,d,qpps)
	rc.SetM1VelocityPID(address,p,i,d,qpps)
	time.sleep(2)
	M1speedPID = rc.ReadM1VelocityPID(address)
	print(M1speedPID)

'MCP236 2x30A v1.1.8\n'
441509 36620 0 372899840
[1, 32767.99998474121, 32767.99998474121, 0.0, 372899840]

I tried to set
P:=6.7369
I:=0.55878
D:=0
QPPS:=5690

converting it x 65536 I got:
P: 441509 I:36620 D:0 and QPPS:372899840
I set this values with method SetM1VelocityPID(address,p,i,d,qpps) BUT reading the PID i get
[1, 32767.99998474121, 32767.99998474121, 0.0, 372899840]

What is wrong?

[fausto.tromba]

shall I receive an answer? I have to insert this feature in the SW and I'm stocked on it.

[Basicmicro Support]

The problem is we are understaffed right now and very busy. The other problem is I did rush my last response.

Using the Roboclaw.py library you dont need to do the conversion. It is already done for you:

Here is the command in the Python library.
def SetM1VelocityPID(self,address,p,i,d,qpps):
return self._write4444(address,self.Cmd.SETM1PID,long(d*65536),long(p*65536),long(i*65536),qpps)

So P I and D are floating point numbers and qpps is an integer.

Im sorry I didnt have more time to understand your question better last time. Hopefully this covers the issue better.

P.S. For a test program remove the code to parse values from a file. Why over complicate a test program like that?