AP-16 does not start correctly

[Jeff Haas]

Jon,

I won an ebay auction for a bunch of EFX-Tek cards.  All are working great except for one AP-16, which is a Rev. D1.  When I turn it on, the status LED never lights.  With or without an SD card in it, it doesn't turn green or red.  I have tried reflashing it with firmware, but there's no reaction from the LED and when I check the SD card, AP16.PGM is still there.

The SD card works in the other AP-16s with test files, and they operate correctly.  And, Prop Tool can see the board and reports that it finds the Propeller chip. 

I can't see any visible damage when comparing the bad AP-16 to a good one.

I realize this is a second-hand sale so no money goes to EFX-Tek, so please don't take too much time on this.  But if there's a way to reset the board I'd like to give it a try.

[JonnyMac]

Since you have a Prop-Plug you might try downloading a simple program that will send something to PST -- this would let us know that the Propeller is running. If you change AP16.PGM to AP16.BINARY then you can download it directly from Propeller Tool.

[Jeff Haas]

I can load a simple program that counts up in binary and sends the result to PST, but it doesn't seem to work.  It works fine on another AP-16.  On the bad one, I load the program and the cursor in the PST window blinks about five times and then freezes.

I can also download the firmware via Prop Tool, it appears to write to eeprom correctly, but there is no change in behavior - the board still doesn't start correctly.

Is there anything else to try?  Or is this one bricked?

[JonnyMac]

Technically, it's not bricked if you can download and run a program.

Okay... there is a back door in our Propeller-based products for testing. Download the code (1.9x beta is the best at the moment) to EEPROM.  You can get that from this thread:

-- http://www.efx-tek.com/php/smf/index.php?topic=2298.0

Open PST and set the baud rate to 115200 baud. Enable PST. Now check and uncheck the DTR box and then start pressing the T key on the keyboard. When the program is booting it should catch this and then go into test mode -- it will display a menu in PST. This will let you exercise the board. This is what we use to verify the board before shipping.

[Jeff Haas]

Thanks for the inside info.

I tried the test mode with a good AP-16 first, to see how it works.  It's very nice and gives you a sense of where the pre- and post- pots actually start to register (there's a small area at the start of their turn that stays at 0).  One thing you didn't mention is that you can't get to the test mode unless you have an SD card in the slot.  Also, with 1.9x, the LED never goes red to indicate that there's no SD card mounted - it stays off.  Putting an SD card in lets you get to test mode and all is fine.

I flashed back to 1.7 and verified that the LED does show red with no SD card.  However the test mode seems to be turned off, I couldn't trigger it in 1.7 (not a surprise, I assume you take that out of production code.)

However, with the bad AP-16, I can't get to test mode.  Even though the Prop chip is seen with F7, and I can download the firmware, it's like the board doesn't boot properly, and so pressing the t key never gets a response in PST.  Something is keeping it from completing the initialization process.

There were two times I turned it on and heard a slight "pop" from the speaker, which is what you hear just before the LED lights.  Once the LED went green, but after it was on, pressing the Start button didn't trigger anything.  One other time I heard the pop but the LED didn't come on at all.

But, no luck getting any farther with either 1.7 or 1.9x.  I also tried swapping out the SD card, no difference.  Both SD cards I have work in the good AP-16.

So I guess it comes down to, what part of initialization could prevent the Prop from finishing starting up?  I assume it's flaky hardware somewhere else on the board.

[bsnut]

I think this is a power supply problem on the board and one of the voltage regulators is shutting down (browning out) or the caps may have dryied out from the board not being prowered up in a while. This can cause a similar problem that you are having with Propeller not booting up. This can be easily checked with your meter to see if you have the 3.3 volts the Propeller needs to operate at.

[Jeff Haas]

I checked the voltage on all four sides of the Prop chip at the VSS and VDD pins - it's getting a steady 3.3 volts, so the 3.3 regulator seems to be fine.

I don't have the tools to really test the capacitors in-circuit.  There are four big ones that look like they're part of the audio out to the speakers (via terminal blocks) but the others are surface mounted.  They all look OK (no bulging, etc.)

[JonnyMac]

However, with the bad AP-16, I can't get to test mode. 

I've attached an update to the latest code that will let you get into test mode even if the SD card doesn't mount. Hopefully, this will help you sort out the hardware.

For those following this thread that don't have a Prop-Plug, you can copy this file to your SD and rename it AP16.PGM; it will auto-load when the AP-16+ is powered on.

Jon

[Jeff Haas]

Jon, thanks for this new firmware.

I tested it with my good AP-16 first.
- With no SD card installed, the LED lights red when the board is powered up.  This issue is resolved.
- I am able to access the test menu and exercise all features.  The tests for the SD card correctly indicate that no SD card is installed, time out, and return to the previous menu.

Then I tried the bad AP-16.
Unfortunately, the same issue appears to keep this version of the firmware from working.  With no SD card installed, the main LED still does not light up at all.
And I am unable to access the test menu via PST, the board is unresponsive.  So the SD card is not what is keeping the board from booting.

I noticed one small detail tonight with the tiny LED next to the EFX-TEK logo.  When a Prop Plug is connected to the good board and it's also connected to the PC, this LED lights dimly if the power is off on the AP-16.  On the bad AP-16, the tiny LED does not light.  Not sure what that means but it may be a clue.

[bsnut]

I still think that this is a power supply problem either with the +5 volt or +3.3 volt or a short in way that is keeping the Propeller from booting up. That's why this led is dim. The question remains, what is the condition of this board and area where the Prop Plug plugs into?

Can you take a good photo of the board so we can what you talking about. 

 

[JonnyMac]

It could be a bad crystal or PLL in the Propeller -- you should, at the very least, see the test menu even if there are other issues.

[Jeff Haas]

Here's a link to a photo of the board.  I'm going out of town for the rest of the week, but let me know if you want a closeup of a specific section when I get back.

https://www.dropbox.com/s/z0sr3c3mahbprvr/AP-16%20bad%20board.jpg?dl=0