Hello Engineers;
        I have a project that controls the position of the
motor. And I have managed to use PIC17C44 to control it
successfully.
        However, I had to erase the PIC whenever I wanted
to change the parameter of the PID. So I decided to make it
user friendly by having the computer to communicate with
the PIC.
        And I did manage to get the computer to communicate
with the USART of the PIC.
        But when the RS232 had the same ground as the
motor, the motor starts to go unstable. When I remove the
RS232 from the circuit, the motor is stable again.
        Does anyone of you knows what is happening?
        Thanks in advance to all engineers.
With regards,
Siong.

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Mr Teik Siong
tsk196@soton.ac.uk