I would like to expand a control system by adding a new 5-relay switching board to my system. Unfortunately, my main control board is already produced without that capability built in.
It occurs to me that the AXE133Y that displays my system status has three I/O pins that are controllable from my main control board and could be used to control the relay board without modifying the main board. Using individual pins and combinations of two pins to make up the other two choices would work, but unfortunately I’m already using one of the I/O pins to control display dimming with PWM and that leaves only two available I/O pins which is not enough to control five relays.
So, I’m wondering about converting one of those I/O pins from a simple HI-LOW pin to a serial out pin with which I can send serial commands to the 14M2 on the relay board to fully control the relays. The command sent to the OLED to flip an I/O pin is 255,X where X is a value to control a specific output pin. My idea is to send a control value which can be retransmitted as a serial output on an I/O pin with a value that would tell the relay board exactly what to do with the relays.
Would appreciate some second opinions on this idea – especially if there is a ‘gotcha’ that I haven’t considered. Is there any reason that this is impractical?
It occurs to me that the AXE133Y that displays my system status has three I/O pins that are controllable from my main control board and could be used to control the relay board without modifying the main board. Using individual pins and combinations of two pins to make up the other two choices would work, but unfortunately I’m already using one of the I/O pins to control display dimming with PWM and that leaves only two available I/O pins which is not enough to control five relays.
So, I’m wondering about converting one of those I/O pins from a simple HI-LOW pin to a serial out pin with which I can send serial commands to the 14M2 on the relay board to fully control the relays. The command sent to the OLED to flip an I/O pin is 255,X where X is a value to control a specific output pin. My idea is to send a control value which can be retransmitted as a serial output on an I/O pin with a value that would tell the relay board exactly what to do with the relays.
Would appreciate some second opinions on this idea – especially if there is a ‘gotcha’ that I haven’t considered. Is there any reason that this is impractical?