MPGuino problem

[trmoore]

I bought a Fundamental Logic V2 MPGUINO kit and assembled as per instructions. I loaded the drivers and uploaded the Arduino sketch as described in the instructions, all appeared to load successfully. The display screen back light is lit but apart from that I get a blank screen. I have repeated the process many times with no success. I assume the bootloader is pre-installed on this kit? if not how can I check? What other checks can I make.

Regards

Terry

[McTimson]

Does it show the blank screen when connected by USB, or when connected in the car?

Also, what version of the MPGuino software are you using?

[trmoore]

It shows the blank screen when connected to the USB, I have not tried to install it in my car as I was expecting to see something on the screen to confirm the program was loaded and everything was functioning. I am not sure which MPGuino version I am using I downloaded it in December and pasted it into Arduino software and uploaded it. (it shows it as sketch 081213a ?) it said done after about 30secs when I uploaded it - the message at the bottom of the screen says Binary sketch size 14194 bytes of 14336 byte maximum. When I reloaded it again just now I no longer get a blank screen but arrows pointing left? But it does not flick through the screens when I push the buttons as described in the installation text.

Thanks

Terry

[dcb]

The serial port working is promising.

All I can think of is do a comprehensive check. Like some arduino script that can use the serial port to turn the pins high and low (or read them) and tell you what lcd pin should be at what value, and the builder would follow along with their volt meter (or an LED + resistor), touching it to different LCD pins.

[trmoore]

This last suggestion will take me some time to study. Electronics is not my forte but I will try reading up on it. I checked which version of the MPGuino I was using it is 10/01/2008 updates for v0.74.

Thanks

Terry

[i_am_socket]

Have you tried adjusting the contrast yet?

Arrows pointing left? That's different.

[trmoore]

Yes, I tried increasing the contrast all I get is a row of black cells. I also tried desoldering the pins connecting the display so I could remove it and check the board circuit out. My attempt to completely desoldering was unsuccessful as enough solder remains to adhere the pins to the holes and I do not want to pry the boards apart, is there a technique to better remove solder I used a simple plunger solder remover. When I attach the MPguino to the USB supply I get 4.2Volts on some of the display pins. I am not sure what that means as I do not fully understand what to check and what readings I should see.

I found this site SparkFun Electronics which has a good tutorial on the components and circuit basics I hope to go through these tutorials to learn the basic electronics. In hindsight I would have been wise to first read these tutorials. Lots of good tips on all aspects of building an Arduino board.

[wagonman76]

Im not sure what all the display pins should get, but it may be such an erratic or high frequency signal that you wont get a true measurement anyway on anything except the power pin and backlight pin for the display. The power pin should be 5.0v, anything less than 4.9 caused problems with mine.

To desolder, get a desoldering braid. It works much better than the plunger. Put a clean section of braid on the solder and the iron on top of it, the solder will come off the board and stick to the braid.

[trmoore]

Thanks for the tip I will buy some braid.

[trmoore]

After many hours desoldering my MPguino and prying it apart (I caused some repairable damage in the process) I finally found the reason why my green display was not working as shown in the construction notes when connected to the USB cable. Simply the USB connection does not supply sufficient voltage to power the screen. I checked the input from the computer USB connection with a multimeter, it reads 4.85V. The output from the 5V regulator was dropped further to 4.12V. I had been reading the lecture notes provided by SparkFun electronics website which states that the 5V regulator needs at least 6.5V to give a 5V output. So at this stage my MPguino was in pieces. Soldering it all together required some patience as I had to use individual wires rather than the pin connectors supplied with the kit (those I trashed in my attempts to desolder and pry apart).

Now that the MPguino was together again - this time it was a mess of connection wires (used a few different colours to make it easier to trace the connections) I connected the board to an independent power supply supplying 9V through the telephone cable and plug. Voila! it works as described - seems obvious now - however I had read a post earlier stating that the USB should be all one needs to power the unit up (clearly for uploading the software yes). What I learnt- read the SparkFun electronics website posted lectures explaining what each component does and how to wire a board up and how to load the software - great easy to read notes highly recommended. I would suggest any newbie to electonics like myself reads these lecture notes first. I hope this note helps others.

Thanks to all those that provided tips. Now to install the unit on my 1995 Mercedes E320 (M104 six cylinder engine).