l298 current sensing

[elleader]

i am using l298 to control 2 dc motors & i used pins 1 & 15 to sense the current through 0.5 ohm resistor by ACD in PIC , but there is a problem that when the load increase at the first motor the current at the second affected ,the same for the second motor too, i don't know why , i can't know the real current of each motor because of this problem , i need help ,,
thanx in advance

 

[moffy]

You could have a common resistance. Often grounding issues are important. There is no way ideally that the currents should interfere without a common path/resistive element. Switching glitches can be misleading as they can capacitively couple through parasitics. As they say, the devil is in the detail. How have you connected your grounds for the PIC and the L298, and how are they connected together? A diagram would help.

 

[elleader]

You could have a common resistance. Often grounding issues are important. There is no way ideally that the currents should interfere without a common path/resistive element. Switching glitches can be misleading as they can capacitively couple through parasitics. As they say, the devil is in the detail. How have you connected your grounds for the PIC and the L298, and how are they connected together? A diagram would help.

Imageshack - overu.png does it help

 

[elleader]

Imageshack - overu.png does it help