I have this basic circuit x2 connected to 2 different I/O pins on a micro, one controls a mini air pump (K1) and the other controls a water valve Solenoid (also in place of K1) Both the pump and the Solenoid are off board, all other parts are on the same board as the MCU:
And I have 2 issues:
#1. If the Solenoid(K1) is ON (output of the MCU is high) the Solenoid is energized and opens as expected. If the second output of the MCU goes high and runs the mini air pump it (I assume) spikes the MCU and the MCU output for the Solenoid goes low and shuts off. I am thinking I need a decoupling cap on the outputs of the CPU?
#2. The same 12 volt power that powers the Solenoid and pump also powers a 7805 that powers the MCU (not shown, but standard stuff). If I remove the 12v input power to the circuit board, but leave the 12 volt power on the solenoid (of board) the solenoid passes power through and powers up the 7805, powering up the MCU. How do I prevent this back feed? I've tested the Schottky and the LED and they both check good.
Thanks
And I have 2 issues:
#1. If the Solenoid(K1) is ON (output of the MCU is high) the Solenoid is energized and opens as expected. If the second output of the MCU goes high and runs the mini air pump it (I assume) spikes the MCU and the MCU output for the Solenoid goes low and shuts off. I am thinking I need a decoupling cap on the outputs of the CPU?
#2. The same 12 volt power that powers the Solenoid and pump also powers a 7805 that powers the MCU (not shown, but standard stuff). If I remove the 12v input power to the circuit board, but leave the 12 volt power on the solenoid (of board) the solenoid passes power through and powers up the 7805, powering up the MCU. How do I prevent this back feed? I've tested the Schottky and the LED and they both check good.
Thanks
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