I tried connecting the GPIO1_0 pin of LPC1114 to the input pin 1 of the ULN2003a IC. And I connected a 9V supply to the COM pin of ULN2003a. For whatever the logic level at pin1 (i/p) of ULN2003a, its corresponding output is always 0.57V. The logic high of the MCU at the o/p gives around 3.1V. What is wrong here?
EDIT: I am trying to drive a stepper motor using the uln2003a as an interface to MCU. I haven't connected the motor yet. I want to make sure it will not burn the MCU. I figured out the common pin of the motor should be connected to the +ve power rail.
- Is it safe to connect the MCU o/p pins to uln2003's input pins without any current limiting resistors between them?
- The Motor's rated voltage & current is 24V and 600mA. The ULN2003A can drive only 500mA. Is it safe to drive the motor at 9V with ULN2003a?