Hardware - Timer Questions

**FredWorrell** · 01-07-2009, 07:30 PM

Hi all! Couple of questions

I am building an input board to condition my inputs to conform to the 0-5 volt requirement. I am incorporating zener protection for all the inputs. I am using a 1,000 ohm resister and 5.1 volt zener to shunt any accidental over-voltage through the zener to ground. Will the 5.1 zener be OK or must I use only 5.0 volt (or less)? I can't seem to find an exact 5.0 volt zener.

Second, exactly what kind of connectors are used for the input/outputs? I want to wire my own and don't know what to ask for.

And last, is there an explaination of just what the four timer do? One thing I want to do is have different sample rates on different inputs, mainly to keep the CPU on my tablet only working as little as possible. Most things I only need data a few times a second.

Thanks for the help!

Fred Worrell

**2k1Toaster** · 01-07-2009, 07:47 PM

5.1 should be ok, just dont rely on it try not to pump overvoltage down it. Anything above 5v can damage the PIC, but it should be able to cope with this little extra. best solution is get a zener less than 5v. doesnt have to be exact, but under is better than over always.

0.1" standard connectors as used on almost all mobos. keep in mind we sell bare wires or femaleconnectors to female for the connections.

the timers split the program into 4 sections. However IO is 1 timer. every time the Brain is polled the full packet is sent back and forth. so only evaluating 1 input of the bunch is a waste.

**GadgetBandit** · 01-08-2009, 10:43 AM

2K,
"the timers split the program into 4 sections."

Can you point to threads that explain the timers?

GadgetBanit

**2k1Toaster** · 01-08-2009, 05:34 PM

4 externally seen timers: input. output, logic, gui.

3 Internal timers that relate to this: I/O, logic, gui

Because the FB requires info to be sent and received each time, inputs and outputs get informmation at the fastest of the 2 timers set by the user. The data isnt available until the external timer says for each input output. So some info will be wasted depending on how they are set. Analogue values and Digital values are updated internally at that speed. Only that.

Logic: Every if statement defaults to using the logic timer. this evaluates whatever you tell it to such as changing a variable, or turning on an output from logic or anything. Logic can be done on any timer though. For instance you may want to update variables on the input if used for other logic since usually thats the fastest or if the variable is for a text box, doing it only on the gui will save resources.

GUI: all it does is draw the gui and check button, states. if your buttons arent responsive your gui timer value is too high (slow).