I am using a PIC16F690 in an application which will control a valve solenoid. The solenoid requires reversing the polarity of the signal to latch open or latch closed the valve. I am using two output pins in the MCU to turn on or off two DPDT relays so that I can switch the polaritiy from a 9 v battery output to the solenoid: 1) MCU Pin1 turning on one relay that is Normally Open (NO) connects the +9 v to the redwire and GND to black wire of the solenoid...turning on the other relay that is NO connects the GND to the redwire and +9 v to the black wire.
The problem I need to solve is how to make sure as a fail safe that both relays are never activated at once by the MCU when it may be going thru powerup or register settings, which means I need a logic circuit connected to the two PIC output pins with the following logic outputs to the relays so that only one of the relays can ever be turned on:
Pin 1 Pin2 RL Output1 RL Output 2
0 0 0 0
1 0 1 0
0 1 0 1
1 1 0 0 'This state is the fail safe!
I have determined the logic circuit to do this is a 2-input XOR gate with its output wired to one of the inputs on each of 2 AND gates, and the individual inputs to the XOR gate also connected to the other input of each of the AND gates. My question is, where can I find a single DIP IC chip that contains at least one, 2-input XOR gate and two, 2-input AND gates, which I can then wire up per above on my MCU circuit board?? I tried to find a CMOS chip that combined these different types of logic gates with no success. Anyone know where I can find one and the part number?
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