February 10, 2010
I have build my own board with a PICAXE-18M and L293D motor driver.
The motor driver uses a seperate power source to power the motors.
When an output signal from the PIC is send to the L293D a LED shows the output is high.
All seems to work without problems; the motors do exactly what i tell them to do and so do the LEDs.
Now for the question.
When i disconnect the PIC's 4.5v power supply and only leave the motor power supply connected, the PIC keeps running.
In other words, the LEDs are still blinking.
I double checked the circuit and the motor power supply + is only connected to the driver IC (and to the correct pin)
Is this normal?
I measured the voltage and it seems around 2v (the motor power supply is 4.5v at this point).
Seems to me this shouldn't happen?
Here is a schematic of the circuit: