O Canada! > Canadian > TekSavvy > Upgrading Firmware on Thompson DCM475

I've now broken down and ordered an Arduino Pro Micro 3.3V board for this project. It should be here on Wednesday, and ought to simplify things: faster comms, and no need for level shifting.

Still looking for a cheaper source for the clip-on connector ($12 shipping for a $12 part??).

Cheers

to forum · permalink · 2012-09-11 11:40:51 ·

mlord

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--
electronicsguru.ca/for_sale/Cablemodems

Update: things are moving along.

Got the 3.3V Arduino board today -- have to get it running soon.
Also have all of the code written and tested (with logic analyzer) for dumping / programming flash on the Arduino.

Haven't found a more affordable source for the (excellent) recommended test clips, but just noticed that the EZ-Hook clips from the analyzer work very well on the in-circuit flash chip. So I'll just use those, since I've got lots of them on hand.

So I'm pretty close to hook-up time. Once I get the new 'duino going, the first task is to rip the 02.08 firmware a few times via different sequences, and do binary compares to judge the reliability of the communications. Then try erasing and reprogramming just the 02.08 firmware, and do readback/verify again.

If that all works, I'll get hold of the 02.16 modem and snatch a copy of the latest firmware from it.

Cheers

to forum · permalink · 2012-09-12 13:26:11 ·

Teddy Boom
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said by mlord:

So I'm pretty close to hook-up time. Once I get the new 'duino going, the first task is to rip the 02.08 firmware a few times via different sequences, and do binary compares to judge the reliability of the communications. Then try erasing and reprogramming just the 02.08 firmware, and do readback/verify again.

If that all works, I'll get hold of the 02.16 modem and snatch a copy of the latest firmware from it.

Install the USBJTAG software and take a look at how cable modem flash is organized on other modems, it will help a lot. If you need a flash dump from a modem, I can pass that along..

In particular, what you'll find is that some of the firmware will be human readable. Try searching for "DCM" and "docsis" in a hex editor. If you've read the firmware properly you should find strings like that. When my friend read a DCM425 chip for me, the bytes always came out flipped:

If I load 425-1.bin into USBJTAG and then inspect image0 I see the
string as follows:
CD4M525-.2803.-1118032S-.Sib.n

Flip the bits and I get:
DCM425-52.08.31-110823-SS.bin.

So maybe it is all just pairwise swapped?!?!

So I googled around a bit and found HEX Workshop, which conveniently has a byte swap feature. Not long after that I had a working ST52.08.31 image.
»www.hexworkshop.com/

Unfortunately no Sayal in Ottawa:
»www.sayal.com/zinc/zinc_contactus.asp
But there must be an electronics supply place.. Not sure about test clips, but they aren't that obscure, so the odds can't be too bad.
--
electronicsguru.ca/for_sale/Cablemodems

to forum · permalink · 2012-09-12 13:57:37 ·

TSI Gabe
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That's called Endianness

»en.wikipedia.org/wiki/Endianness

x86 are little endian

While in this case is likely MIPS based which is usually big endian.
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TSI Gabe - TekSavvy Solutions Inc.
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to forum · permalink · 2012-09-12 14:19:15 ·

Teddy Boom
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said by TSI Gabe:

That's called Endianness

Thanks! I've heard of little endian and big endian before, and I probably even dealt with the ideas a little 15 years ago, but I sure didn't make the connection.

I mentioned that I'm an analog guy right?

to forum · permalink · 2012-09-12 15:12:13 ·

mlord

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The test setup.. forgot to disconnect the Logic Analyzer

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. I was all set to do it, but just hooked things up without it for a trial, and it all works!

Dumping 32mbits of flash now.

to forum · permalink · 2012-09-12 17:12:22 ·

Teddy Boom
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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:

Looking good

--
electronicsguru.ca/for_sale/Cablemodems

to forum · permalink · 2012-09-12 17:27:35 ·

mlord

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SPI activity

Well, that wasn't so bad. I've now got an exactly 4 MByte file with a binary dump of the entire flash chip inside. Oddly enough, none of the flash is write-protected either, according to the chip status register.

I'm going to dump it a few more times and check for bit errors between the various dumps. Meanwhile, here's a look at the logic analyzer display during the dumping..

to forum · permalink · 2012-09-12 17:34:16 ·

mlord

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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

to forum · permalink · 2012-09-12 17:38:34 ·

mlord

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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.

to forum · permalink · 2012-09-12 17:43:26 ·

TSI Gabe
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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.
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to forum · permalink · 2012-09-12 18:41:26 ·

mlord

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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

to forum · permalink · 2012-09-12 20:28:35 ·

mlord

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said by mlord:

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

After some research, it turns out it wasn't dead after all -- just getting stuck somewhere. I've revived it now, and the setup is much simpler using it, with built-in USB and 3V logic. Just six(6) wires from it to clips on the flash chip, and nothing else required.

After I re-rip the flash a few times, I'll start playing with the scarier business of erasing/programming the flash and see how that turns out.

Very, very, close now!

to forum · permalink · 2012-09-13 12:34:48 ·

mlord

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Six minutes and thirty-seven seconds to rip and transfer the 4MBytes of flash, using a 1Mhz SPI clock. That's good, I suppose. Programming will be slower.

Speaking of which, I can't just shove the entire image from another modem into this one, or can I? Surely there's an area in flash that records the MAC addresses for the modem? I do see the MAC address in several places, in both binary and formatted ASCII.

Teddy Boom?

to forum · permalink · 2012-09-13 14:05:48 ·

mlord

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Okay, there are several distinct regions within the 4MBytes of flash.

The first 64KB appears to be a fixed "bootloader" area, including MAC address and various crypto certificates.

The area from 0x010000 to 0x1fffff (2MB less 64KB in size) is likely the "factory image" area. This consists of a firmware code image, plus padding. The odd thing is, there's a bunch of "junk" in the first few 64KB blocks following the "used portion" of the image here, possibly leftovers from an earlier/larger "manufacturing/test image" at the factory. The "regular" image padding appears to be 16KB blocks of 0xffffffff, except with the first 32-bits of each 16KB block zeroed out 0x00000000.

The area from 0x200000 to 0x3effff (same size as above) looks like the "secondary image" area, used for new firmware downloads in the field. The suspicion is that if a valid image is found here, then the booloader uses it rather than the "factory" image. Currently on my modem, it's a duplicate of the factory image, minus the "junk", with "regular" padding as described above.

It's not clear if field upgrades alternate between the two images, or always go only to the second image. I can probably find out with some experimentation once I have the 02.16 image to play with alongside the 02.08 image.

The final 64KB of flash is mainly used as a set (two sets?) of log buffers.

Since none of the flash has been write-protected, it's easy to do all kinds of experimentation without having to lift the WE (Write Enable) pin.

Time to start erasing/programming things now.

to forum · permalink · 2012-09-13 18:00:15 ·

vientito1

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Is Rogers the only company refusing to upgrade firmware? How about Videotron? Are they holding the same deplorable attitude and practice?

to forum · permalink · 2012-09-13 18:43:27 ·

mlord

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Dunno. But for most modems, we can now do it ourselves, or take/send it to Toronto to have it done. I'll be offering updates to DCM-475 modems here in Ottawa shortly.

Cheers

to forum · permalink · 2012-09-13 18:44:47 ·

Gone
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