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Teddy Boom
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join:2007-01-29
Toronto, ON
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reply to mlord

Re: Upgrading Firmware on Thompson DCM475

said by mlord:

Unfortunately the new 3.3V Arduino w/USB died after just a minute or so of use.

So for now, I'm back to the serial port version at 5V. Turns out level shifting is a non=issue.

Interesting... I think maybe the 3.3V got over loaded because of other loads on the modem board. Maybe the 5V Arduino is more robust--outputs more current. It takes around 0.5A from my bench supply when I apply power direct to the chip in circuit, some modems close to 1A.

5V is on the edge really.. If it is really 4.8V, then I'm sure it is pretty safe (though I'd like to keep it 4V and lower normally). If it is really 5.5V I think you are risking the modem..
said by mlord:

...
00009f50 00 6a 00 69 00 0a 50 70 61 6e 00 01 00 01 00 08 |.j.i..Ppan......|
00009f60 6d 46 57 4c 00 01 00 08 52 53 54 4c 00 01 00 19 |mFWL....RSTL....|
00009f70 54 48 4f 4d 00 01 00 00 07 44 43 4d 34 37 35 00 |THOM.....DCM475.|
00009f80 00 04 31 2e 30 00 00 00 4c 52 43 41 20 00 03 00 |..1.0...LRCA ...|
00009f90 00 00 00 44 43 4d 34 37 35 00 00 00 00 00 00 00 |...DCM475.......|
00009fa0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
...

More later, whenever it finishes (hours, likely).

Looking good
--
electronicsguru.ca/for_sale/Cablemodems

mlord

join:2006-11-05
Nepean, ON
kudos:13
Reviews:
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3 edits
said by Teddy Boom:

said by mlord:

Unfortunately the new 3.3V Arduino w/USB died after just a minute or so of use.
So for now, I'm back to the serial port version at 5V. Turns out level shifting is a non=issue.

Interesting... I think maybe the 3.3V got over loaded because of other loads on the modem board.

No, it died before ever being connected to anything other than my PC's USB port. A not uncommon issue, apparently. I'm checking to see if I can get it replaced under warranty.

quote:
5V is on the edge really.. If it is really 4.8V, then I'm sure it is pretty safe (though I'd like to keep it 4V and lower normally). If it is really 5.5V I think you are risking the modem..
I'm powering the flash chip with 3V, but feeding it TTL signal levels for the SPI lines. A paper I read earlier suggests this is kosher, and thus far it seems to be. The only real concern was whether the MISO data line from the flash chip would have a high enough logic "1" voltage to work with the Arduino. Correction: I did keep the level conversion for MSIO after all. So just that one line (data-out from the flash chip) gets up-shifted to 5V logic.

Cheers

mlord

join:2006-11-05
Nepean, ON
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Mmm.. interesting. You know how these modems always chop off the log messages displayed in the web interface? Well.. the full log messages (not chopped) are stored near the end of flash.


TSI Gabe
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Gatineau, QC
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I've been meaning to get one of these for a while.

»www.adafruit.com/products/757

Conversion from 3.3 to 5v or the other way around is way too common.
--
TSI Gabe - TekSavvy Solutions Inc.
Authorized TSI employee ( »TekSavvy FAQ »Official support in the forum )

mlord

join:2006-11-05
Nepean, ON
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1 edit
Yeah, that's the same type of gizmo I'm using here, except mine is from SparkFun: »www.sparkfun.com/products/8745
Edit: But I like the one you posted the link for even better. Gotta get some!

Handy little sucker. I'm actually using the "LV" (Low Voltage) side to POWER the flash chip in-circuit inside the modem. Works rather well!

After disconnecting the logic analyzer, the loading on the pins is now low enough that I'm getting very consistent error-free dumps every time. Takes just under 19 minutes to dump all of flash in ASCII-hex (with spaces) over the serial link. I can speed that up by eliminating the spaces between byte values, which ought reduce the time by 1/3 or so.

At this point, I'm just about ready to borrow a modem with 02.16 firmware to read the image out of.

Cheers