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Forum Index : Microcontroller and PC projects : Maximite Test ver 2.5C - with serial, I/O

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wizard

Newbie

Joined: 29/07/2011
Location: United States
Posts: 38
Posted: 01:49pm 08 Sep 2011
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Hi Geoff,

Thanks.
I get a clean symbol table from nm Maximite.elf.
Now I just gotta teach my disassembler to intermix symbol names.

I am thinking it would be nice to be able to compile and interlink
some MMBasic add ons. An elf loader would also be nice. Thankfully
its all open source.

It all just SMOP - Small Matter of Programming ( consultant's joke :).

Wiz
 
Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3194
Posted: 12:12am 09 Sep 2011
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Marc,

Are you powering your Maximite from the USB?
If yes, could you try with an external power source (eg, 9V).

Versions greater than 2.5B draw a little extra current and that may be the issue. The bootloader draws a lot less current so that could explain why it still runs OK.

Fingers crossed,
Geoff
Geoff Graham - http://geoffg.net
 
VK6MRG

Guru

Joined: 08/06/2011
Location: Australia
Posts: 347
Posted: 01:00am 09 Sep 2011
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Just so everyone knows, I only use USB power.
Its easier to ask forgiveness than to seek permission!

............VK6MRG.............VK3MGR............
 
VK6MRG

Guru

Joined: 08/06/2011
Location: Australia
Posts: 347
Posted: 01:07am 09 Sep 2011
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Geoff, I have plugged in an external power supply and I have run the tests again.
Even with the External power I have the same problem with 2.5c/d/e versions of MMBasic. Could it be that the chip has the problem? Dud chips do happen.
Marc, do you have or can you get another Maximite to verify the problems that you are having.
Its easier to ask forgiveness than to seek permission!

............VK6MRG.............VK3MGR............
 
thetinkerer

Regular Member

Joined: 16/06/2011
Location: Australia
Posts: 68
Posted: 12:43pm 09 Sep 2011
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Hi there Guys,
I am back! Been busy with work etc.
I have just tried firmware V2.5F and powered it with a plug pack and it works!!!
So I switched it back to USB power and no go!

I will dig out my other Maximite tomorrow and try it too.


Thanks for all the help guys.

regards

Marc
 
Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3194
Posted: 09:07pm 09 Sep 2011
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Hooray. The USB power must have been just on the limit of what it could supply.
Geoff Graham - http://geoffg.net
 
thetinkerer

Regular Member

Joined: 16/06/2011
Location: Australia
Posts: 68
Posted: 05:22am 10 Sep 2011
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Hi Geoff and All,
Just for info, I just did a little probing around and found the following voltages and currents(measured at JP1:

Running Firmware 2.5F on an Altronics Maximite.

Power Voltage Current
USB hub 4.62v 136ma (usb comms doesn't work)
Pc USB 4.9v 132ma (usb comms doesn't work)
Ext Power 5.07 137ma (USB comms works)

I didn't think that 4.9V would be an issue.


regards

Marc

 
thetinkerer

Regular Member

Joined: 16/06/2011
Location: Australia
Posts: 68
Posted: 08:23am 10 Sep 2011
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Hi Geoff and All,
Just for info, I just did a little probing around and found the following voltages and currents(measured at JP1:

Running Firmware 2.5F on an Altronics Maximite.

Power Voltage Current
USB hub 4.62v 136ma (usb comms doesn't work)
Pc USB 4.9v 132ma (usb comms doesn't work)
Ext Power 5.07 137ma (USB comms works)


Running Firmware 2.5B on an Altronics Maximite.

Power Voltage Current
USB hub 4.59v 141ma (usb comms work)
Pc USB 4.9v 136ma (usb comms work)
Ext Power 5.04 141ma (USB comms works)


I didn't think that 4.9V would be an issue.


regards

Marc
 
VK6MRG

Guru

Joined: 08/06/2011
Location: Australia
Posts: 347
Posted: 08:29am 10 Sep 2011
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Out of interest, have you measured the 3.3v reg output voltage?
Its easier to ask forgiveness than to seek permission!

............VK6MRG.............VK3MGR............
 
Geoffg

Guru

Joined: 06/06/2011
Location: Australia
Posts: 3194
Posted: 12:53pm 10 Sep 2011
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It is strange, especially when one version worked on 4.9V and the other did not. 4.9V is definitely within spec, the lower design limit is 4.5V.

I wonder if the issue is noise on the power line. I have found (as others have) that the PIC32 is very sensitive to noise on Vcap (pin 56) and if the 10uF cap (C5) is marginal in its specs, the noise might enough to tip the issue over.

If you feel like messing with your Maximite it would be interesting to see how it works with a 22 or 47uF tant cap in parallel with C5. I bet that it will work.

GeoffEdited by Geoffg 2011-09-11
Geoff Graham - http://geoffg.net
 
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