Unable to communicate with megajolt

l555chris · Post by **l555chris** » Sat May 20, 2006 4:04 pm

Hi,
I know this topic has come up a million times before, I've looked through the old posts and can't find anyone whoâ€™s had quite as little success as I have!

The MJ (v3) is powered off a mains regulator at about 10v. 5v is available in all the places on the board that it should be.

The serial cable I'm using is a home made one, pins 1-5 connected straight through.

I don't get any response from the HT test: Nothing when you throw C at it, nothing when you initially power the board up with it connected.

The MJ tuner can't connect to MJ

I've re-installed java and the comm files.

I'm reluctant to try re-flashing the chip just yet as I've heard that I could screw it up even more and add another unknown into the equation.

Does anyone else have any suggestions of my next steps? Are there any of the discrete components that prove troublesome?

Many thanks,

Chris
PS - board set up in TPS config if that makes a difference

4600cc · Post by **4600cc** » Sat May 20, 2006 9:54 pm

Capitalize C, and S commands when you send it to megajolt. Make sure serial is configured properly too.

Magnolia · Post by **Magnolia** » Tue May 23, 2006 4:54 am

Just a thought, when I used to make cables up I ocassionally would forget that the pin #'s start on opposite ends of the connector for male and female.

l555chris · Post by **l555chris** » Sun May 28, 2006 10:13 am

Thanks for your replies,
I'm confident I've got the serial cable wired up with the right pins through (both my connectors have the numbers embossed next to the pins) do you need to connect the two outer D bits?

I've tried the capital C / S commands with no joy. In terms of configuring the serial port, I've used the correct baud rate, flow control , etc settings.

Is there anyone in the Warwickshire area in the UK who has had success who wouldn't mind me trying my MJ on their machine?

How often do people see problems with IC failures?
Are there any more detailed checks I can perform on the board apart from verifying the 5v power supply (which is fine)?

Many thanks

Chris

SRandle · Post by **SRandle** » Sun May 28, 2006 8:16 pm

Hi Chris

I am in Rugby if thats close by.

Regards,

Steve.

steve100 · Post by **steve100** » Mon May 29, 2006 9:33 pm

Are you sure you have the serial cable correct - from my recollection of serial cables, pin 2 of plug A goes to pin 3 of Plug B, while pin 3 of Plug A goes to Pin 2 of Plug B. - it is not wired 'straight through ( ie NOT 2 to 2 , 3 to 3)
Steve

MartinM · Post by **MartinM** » Mon May 29, 2006 10:27 pm

The serial cable for the Megajolt is definitely 'straight-through' (2-2, 3-3).

Are you connecting directly to a real PC serial port? Via a USB Adaptor? Or something else?

I've just built two Megajolts tonight - that's about 8 I've built now and never had a problem - until on one of them tonight!

The problem was a faulty oscillator (QG1)- the diagnosis is that pin 10 of U1 (the main processor) should have a 16Mhz square wave on it. If you don't have an oscilloscope to hand to check, you can measure the voltage with a multimeter - should be 2.4 volts or so. My faulty one had no square wave and 0 volts when measured at pin 10 of U1. Replaced the oscillator (it was brand new anyway) with another and instant success. Don't know why the first oscillator was faulty though....

l555chris · Post by **l555chris** » Tue May 30, 2006 11:56 am

Hi,
I'm connecting to a real serial port. Tried it on 2 windows PCs and a linux machine...no joy on any of them.

My gut feeling is that it is a hardware problem on the MJ side, I think my soldering is ok however I remember hearing somewhere (either on here, the tigers owners forum or the locost builders forum) that some diodes won't work with the MJ because the current used is so little, has anyone else heard of that problem?

Thakns for the tip on the oscillator, I'll try that this evening.

Steve, I'm in Leamington. Would you mind meeting up to try and program my MJ with your cable / computer?

Thanks again,

Chris

MartinM · Post by **MartinM** » Tue May 30, 2006 2:30 pm

Chris

You can put it in the post to me if you wish - I have enough test equipment to find out the problem and spares to fix it. I've done it for another forum member (can supply references if required!) and it all worked out well

2 way postage and an (almost) guaranteed fix will be cheaper and easier than meeting up with someone else, I would suggest.

Put an email address in your reply (you can edit it out once I've captured it) and we can continue off line if you're interested...

Martin

l555chris · Post by **l555chris** » Wed May 31, 2006 11:46 am

Martin,
Thanks for your kind offer, e-mail me at chrisst170@hotmail.com and we'll discuss it offline.

Cheers,

Chris

MartinM · Post by **MartinM** » Wed May 31, 2006 12:07 pm

Email address extracted - you can delete it if you don't want to leave it for the spammers to pick up!

Will be in touch later today....

andre saethern · Post by **andre saethern** » Wed May 31, 2006 1:11 pm

I seem to have this very problem. I cant get them to communicate. only difference from above is that I use an usb adapter. It seems to understand that its named COM1 though....

MartinM · Post by **MartinM** » Wed May 31, 2006 6:57 pm

Well I guess the offer is open to you as well! Are you in the UK?

andre saethern · Post by **andre saethern** » Wed May 31, 2006 7:42 pm

im in Norway, think I will resend to the person who made it for me first!I have tried almost everything now, and still no go.

but we will see. thanks for the offer!

Autosport Labs

Unable to communicate with megajolt

Unable to communicate with megajolt

Capital letters, not lower case, C and c are different.

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Serial port unable to communicate wit Megajolt

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comms with megajolt

Chris

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I seem to have this very

Well I guess the offer is

im in Norway, think I will