Need to test a BS2px and SX-28 for basic functionality

T&E Engineer

I need to test out a BS2px and SX-28 to make sure that it still works. I built a large circuit that did work for some time well·but it is in a location that has power outages and spikes from time to time. I don't know if this is the issue or not as I am not able to visit the location - out of state. The circuit has an LCD and keypad and now takes 10 minutes to display information after power up. Now I hear it does nothing even after 10 minutes (originally - it displayed immediately).

Does simple re-programming the microcontrollers prove that they are ok or should I write (or is there anything already written) to maybe do something like turn on all the outputs with LEDs or something?

Any ideas?

Thanks.

Mike Green

A lot of things have to work for the microcontrollers to be able to be re-programmed. The question is: What could be going on that takes 10 minutes to display information? Perhaps the power supply is intermittant or marginal and the controllers keep resetting. Perhaps there's something the controllers are programmed to do before displaying and that's not working. Do you have a backup unit on hand that you could experiment with? How would you re-program them? Do you send out a tech (else who would see the LEDs?) Part of the reason for mentioning a backup unit is that you'd have to debug the test program on working hardware. You're not going to do that remotely!

Typically, test programs start with a minimal core of hardware that must work to get to the point of lighting an LED, then the program successively tests parts of the system (like the display, then the keyboard). Not knowing what you system consists of, it's hard to suggest an order to things. Usually, you want to test simple parts first. If those are broken, there's no point in continuing.

T&E Engineer

I tested everything before it left to the client many months ago. At the clients site (out of state), he reported all worked fine until a month or two later when if they lost power, it would take 10 minutes for it to display anything on the LCD (parallax serial 4x20). I thought that was weird but the client was ok for the moment. He kept saying that he thought it might be to power fluxuations or spikes as it is a common occurance he said. I could probably mock up a simplified version of the circuit but I never saw the issues he has. I beleive he wants to send me the suspected microcontrollers and see if they are bad. All I would do is make sure they can communicate (e.g. reprogram the BS2px and SX-28 code) - as they don't have the technical ability or equipment to do so. I would then put them through a test of the outputs to make sure they function but I'm not sure if anything else needs to be done after that. I would send them back and see if this corrects the problem. Perhaps he should also send me the LCD too.

The circuit is quite simple but large. It uses a keypad with a modified version of the SX-28 SX/B program HELP file for 4x4 keypad. It sends the character out serially TX, RX to the BS2px to read. When 4 correct numbers are entered into the keypad the BS2px interprets it and sends out a clock pulse to a set of cascaded 4017 decade counters (110 of them). One of the ~700 outputs of the 4017 turn on a LED for 3 minutes unless the user hits the BS2px reset button allowing him to enter in a new 4 digit code. Thats basically it. It is a simple lookup routine.

I beleive most of the time the client is busy as I will communicate with him and maybe wont hear back for a couple of weeks at times.

Thanks.

Mike Green

Boy, there are so many things to go wrong there and no way to check them with your setup. I would suggest making up a BS2px with a test program in it that the client can swap out. It would:

1) Display a message on the LCD indicating that it had finished initializing (like "Hello")

2) Output pulses to the 4017 chain and count up on the display (every 10 or 100 pulses so as not to slow things down too much) indicating when the output was sensed or that it wasn't sensed when expected.

3) Display the characters received from the SX-28 keypad scanner

I suspect that it's not the microcontrollers. They tend to be very robust. I think it would be a better use of everyone's time to simply send a replacement SX-28 (if it's socketed), the test BS2px, and a replacement BS2px.