Hello,
I am "trying" to design a PCB to drive 8 solenoid valves or have 8 actuator i/p's using a ARM9 based MCU. The I/O lines of the MCU will of course be used to activate the solenoid valve, the MCU supply is 3.3V and the Solenoid valves are either 24VDC or 24VAC (haven't made a decision on that) of course the first thing that come to mind is to use a opto-isolator to trigger the 24V off the 3.3 V o/p of the I/O line.
Here is my problem I would like to use the I/O line as either a 24V supply for the solenoid in which case the MCU line will be an o/p BUT I would also like to use the same line to connect an actuator switch in which case the MCU line would be configured as an input to detect a switch closure. As far as I know optoisolators are uni-directional (have seen a bi directional optoisolator but it has only one channel I would like to have at least 8 such bidirectional I/O ports configured so I would like to have 8 channels or at a minimum 4 per chip so that the board hardware doesn't go out of control and not waste I/O lines on the MCU). Might be a really easy solution out there and I should be ashamed to call myself a EE guy for not knowing it, but if someone could suggest a solution other than the optoisolator I would appreciate it.
Thanks......
I am "trying" to design a PCB to drive 8 solenoid valves or have 8 actuator i/p's using a ARM9 based MCU. The I/O lines of the MCU will of course be used to activate the solenoid valve, the MCU supply is 3.3V and the Solenoid valves are either 24VDC or 24VAC (haven't made a decision on that) of course the first thing that come to mind is to use a opto-isolator to trigger the 24V off the 3.3 V o/p of the I/O line.
Here is my problem I would like to use the I/O line as either a 24V supply for the solenoid in which case the MCU line will be an o/p BUT I would also like to use the same line to connect an actuator switch in which case the MCU line would be configured as an input to detect a switch closure. As far as I know optoisolators are uni-directional (have seen a bi directional optoisolator but it has only one channel I would like to have at least 8 such bidirectional I/O ports configured so I would like to have 8 channels or at a minimum 4 per chip so that the board hardware doesn't go out of control and not waste I/O lines on the MCU). Might be a really easy solution out there and I should be ashamed to call myself a EE guy for not knowing it, but if someone could suggest a solution other than the optoisolator I would appreciate it.
Thanks......