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Diagnosing Issues

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Asbelos edited this page Sep 23, 2020 · 4 revisions

Diagnosing Issues (aka "Something's not working!")

There are a lot of optional settings and choices a user can make and sometimes things don't work as you expect them to. If you upload software to the Command Station, connect power to your motor controller and the CS and then connect the output to your track and don't see power or your train responding, here are the steps to follow.

Is it plugged in, is it turned on

Yes, we need to start with the basics. If you have 12V DC or less connected to the input power of the Arduino and did not cut the power connect trace underneath the Motor Controller, then the Motor Controller and the Arduino can be powered from the one power supply. If you cut the trace, then you will need two power supplies, a 9V DC power supply to the Arduino and a 12-18V DC (based on the scale of your locomotives) power supply for the Motor Controller.

  • If you have one power supply, is it plugged into the wall and is it at least capable of delivering 2 Amps of current?
  • If you have two power supplies, see above for the Motor Controller board and add a 9V power supply for the Arduino of at least 1 Amp
  • Do you see lights on the Arduino indicating it has power? If not, there is a power issue
  • If you go into a Serial Monitor, like the one in the Arduino IDE, and type "<1>" and "Enter", do you see all 4 lights come on with an Arduino Motor Controller Board? If not, there is a problem with the software or the connection

Diagnosing and Testing

  1. Remove the Motor Shield ---we are going to test just the Arduino first.
  2. Download and install the most current version of DCC++ EX Command Station
  3. Open the Serial Monitor Window in the Arduino IDE and establish communication with the Arduino. You will need to set the serial data rate to 115200 baud and make sure you have . If you see gibberish (garbage characters), this is usually an indication that the baud rate is incorrect. You will also need to make sure you set the other dropdown next to baud rate to "both NL & CR" to send both a new line and carriage return when you enter commands

###Testing the Arduino and Base Station code###

THIS SECTION WILL NOT WORK PIN 13 IS A PROG TRACK CONTROL PIN ON A STANDARD MOTOR SHIELD

Next, we are going to utilize the built-in on-board LED attached to pin 13 to test the Arduino and Base Station code. This series of tests only works if you are NOT using pin 13 for any sort of output (using it as an input is okay).

  1. Connect a jumper from pin 13 to whatever pin you have defined (or was already defined in the software) for SIGNAL_ENABLE_PIN_MAIN
  2. The LED next to pin 13 (SEE ABOVE ) should go off (or remain off, if it was already off)
  3. Send a < 1 > command to turn on track power --- the LED should go on.
  4. Send a < 0 > (that's a zero) command to turn off track power --- the LED should go off.
  5. Repeat this a few times to check for robustness.
  6. Assuming this works, now perform the same test for the the programming track by connecting the jumper from pin 13 to whatever pin is defined for SIGNAL_ENABLE_PIN_PROG.

If either of these tests fail, first review the DCC.h file to make sure you are indeed testing the right pins and matching SIGNAL_ENABLE_PIN_MAIN and SIGNAL_ENABLE_PIN_PROG. If one or both of these pins is not able to control the LED attached to pin 13, there is likely something amiss with the Arduino itself.

If both tests pass, it means the Arduino should be able to correctly enable/disable track power, at least from its perspective.

###Testing the DCC signal###

Now the fun part -- we are going to test the generation of the DCC signal itself.

  1. Move the jumper once again so you are now connecting pin 13 to whatever pin is defined as DCC_SIGNAL_PIN_MAIN.
  2. The LED next to pin 13 should go on, regardless of whether track power is set on (<1>) or off (<0>). Track power control does not alter the actual DCC signal generation on the Arduino.
  3. Now send a <D DCC SLOW> command to the Arduino --- this SLOWS DOWN the entire system clock by a factor of 256, and also slows down the speed of the timers generating the DCC signal.
  4. The LED next to pin 13 should now be blinking - mostly fast, but sometimes a little slower for just one or a handful of blinks. This is the actual DCC signal. Fast blinks represent a one-bit, slow blinks represent a zero-bit.
  5. You'll note that once you send the < D > command, the Arduino will respond with a message indicating "Entering diagnostic mode..." This is the last communication you will be able to send or receive while the window is open. To re-establish communication and reset the clock speed you will need to close and re-open the serial monitor window, or cycle power on the Arduino, or hit the reset button on the Arduino. But don't do that just yet.
  6. Repeat the test for for programming track DCC signal by moving the jumper to connect pin 13 to whatever pin is defined as DCC_SIGNAL_PIN_PROG.
  7. You do not (actually cannot) need to send the < D > command again - the Arduino will still be in diagnostic mode unless you've close and re-opened the serial monitor window.
  8. As before, the pin-13 LED should now be blinking. The program-track DCC signal defaults to the same as the main-track DCC signal when the system first starts so the blinking pattern of ones and zeros should be the same.

If either of these tests fail, first review the DCCpp_Uno.h file to make sure you are indeed testing the right pins and matching DCC_SIGNAL_PIN_MAIN and DCC_SIGNAL_PIN_PROG. If you are and one or both of these pins is not causing the pin-13 LED to blink, then that suggests there is something wrong with the Arduino timers or interrupts. But before drawing that conclusion, run the entire test a few more times to double-check, since the new diagnostic command is...well, new.

###Testing the Motor Shield###

If first two tests pass, then the Arduino is functioning correctly and it's time to test the Motor Shield.

  1. Power down the Arudino
  2. Install the Motor Shield, and make sure it has power, though do not connect to the tracks
  3. Verify that all of the mappings are correct, and that the signals on the Motor Shield are properly being mapped to the enable and signals pins you identified above.
  4. Open (or re-open) the Arduino Serial window
  5. Send a < 1 > command.
  6. All 4 lights next to the outputs of the Motor Shield should be on
  7. Send a < D TEST > command to enter diagnostic mode
  8. All 4 lights should now be blinking - the two attached to one output channel should blink in alternation, and the two attached to the other output channel should also blink in alternation.

If neither of the LEDs attached to one of the output channels comes on when you send a < 1 > command, this indicates you are not correctly mapping either the SIGNAL_ENABLE_PIN_MAIN or SIGNAL_ENABLE_PIN_PROG pins from the Arduino (depending on which output channel does not appear to be working). From the above tests, we know those pins on the Arduino are working, so it must be in the wiring or jumpers between that Arduino pin and the pin used to enable to the Motor Shield for that channel (if indeed a wire or jumper was needed at all).

If only one of the LEDs attached to the one of the output channels comes on when you send a < 1 > command, but the other does not, this suggests that either the DCC signal is not getting through to the Motor Shield, in which case it is a mapping/wiring/jumper problem, OR that the signal is getting through but the H-bridge on the Motor Shield itself is not functioning (and the Motor Shield may need to be replaced). To see which is the case, check whether the lone-LED begins to blink once you send the < D > command. If it does not, that indicates that problem is in mapping the DCC signal generation pin (which we know is working from the above tests), to the Direction pin on the Motor Shield. If the lone-LED does start to blink after sending a < D > command, but the opposing LED does not blink in alternation, then something is wrong with the Motor Shield and it likely needs to be replaced.

If you still need help, please find us on Discord or send an email to [email protected]

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