I must manage the SSR with 2 microprocessors. I MUST. But I think this circuit is okey.
First Microprocessor is Arduino and second is PIC 16F628A. PIC is EXTRA system. If Arduino fails pic will work.If pic fails Arduino will work.
I need circuit that operate the SSR with 2 microprocessors. I thought OR gate would be helpful.
But I am not sure about the Servo's. How can I control servo's through SSR with 2 microprocessors.
Because of the Analog data problem.
Can I set the Servo's (SG-90) just to turn 180 degrees
(I forgot to add 12V-5V Voltage Divider to Servo's at the diagram)
Please help if you find something wrong in this circuit and how to change them.
here , the system diagram and datasheet of the OR Gate (74LS32)
it's not obvious how a processor indicates it is not failed. one approach is a watchdog time, something that needs to be pet periodically.
i think an S-R flip flop could work. if the inputs are active high (indicating processor OK), there is just one active low output to control which process is master
I just need to guarantee SSR's working. But I confused about the logic. So,yes : if the output of the Arduino Pin is 1 ssr would work or output of the pic is 1 ssr work or output of them (Arduino und Pic) is 1 ssr would work. I must guarantee the system is working.
Arduino may be break or Pıc may be break. So it is a backup system
First define what you mean by “failed”...
There are any number of DIFFERENT ways a microprocessor system may fail.
For example it may just stop running completely, or it may lock up in a certain state due to a power brown out or other hardware or software issue.
The problem with a lockup is that that microprocessor may be driving the output high at the time. What will happen with your design in that case?
Make a list of all of these, what might happen to the outputs in each case, and how you plan to mitigate that.
But in the very basic failure case of one micro, not having run any code yet to set its outputs high, and the power to the OR gates not failing, and (somehow) there not being any required synchronisation between the two systems (e.g. relay A must never be on at the same time as B, etc) your example will work.
gcjr:
you're not answering the questions?
you're repeating yourself
what is the state of the failed processor outputs?
I am not repeating myself Fail means: Arduino is not working. The battery of the arduino is dead. Or maybe battery of the PIC is dead. Quite obvious no output no signal
gunesmadrali:
Fail means: Arduino is not working. The battery of the arduino is dead. Or maybe battery of the PIC is dead. Quite obvious no output no signal
battery failure is one type of failure. Processor lockup is another
gcjr:
battery failure is one type of failure. Processor lockup is another
Yes , there could be many failure in this system. The point I must emphasizes what would be the respect of OR gate if Arduino and PIC works simultaneously. Can there be a signal confusion here.Of course probably PIC and Arduino will work. I don't think so there will be a problem here but I have to think about worst scenario because it is an Avionics Sytem so there must be a second system that if the first system fails other will work. Consequently I thought OR GATE would be helpful. So yes both systems will work at the same time. Maybe one of them has a software mistakes or power failures.
For that I must use 2 microprocessors that will guarantee the system. (I need to trigger SSR's at right time for parachute deployment system)
pcbbc:
First define what you mean by “failed”...
There are any number of DIFFERENT ways a microprocessor system may fail.
For example it may just stop running completely, or it may lock up in a certain state due to a power brown out or other hardware or software issue.
The problem with a lockup is that that microprocessor may be driving the output high at the time. What will happen with your design in that case?
Make a list of all of these, what might happen to the outputs in each case, and how you plan to mitigate that.
But in the very basic failure case of one micro, not having run any code yet to set its outputs high, and the power to the OR gates not failing, and (somehow) there not being any required synchronisation between the two systems (e.g. relay A must never be on at the same time as B, etc) your example will work.
Thanks; You are right there could be a many mistakes. I believe both systems will work except unexpected statues but I have to take into account some failures.
The easiest failure example can be shown as a power problems.
For example at the 10th second first Servo at 20th second second servo at 30th second 3th servo at 40th second 4th Servo will work (Not my algorithm just a hypothetical example) . So I believe they will both work at the same time. And suppose the codes are correct, too. I wonder that what would be happen if the energy in the pins reaches the pins of the gate at the same time or in small different periods depending on the crystal time. Can my system work successfully?
