RCA DTA800 Digital to Analog TV Converter Box - Page 14 - AVS Forum
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post #391 of 416 Old 08-15-2013, 08:31 AM
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A few boxes have a smart antenna input.
BTW the Zenith was only rated in the middle of the pack on PQ per that consumerreports.org link I provided you on one of these threads. Also, Insignia is the same as Zenith (they're actually all made by Insignia).

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post #392 of 416 Old 08-16-2013, 07:52 AM
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Quote:
Originally Posted by Floydage View Post

A few boxes have a smart antenna input.
BTW the Zenith was only rated in the middle of the pack on PQ per that consumerreports.org link I provided you on one of these threads. Also, Insignia is the same as Zenith (they're actually all made by Insignia).
Later model DTA800B and DTA800B1 units omit the smart antenna input - and to my knowledge, very few smart antennas reached the consumer marketplace. Anyway, I enjoyed using this CECB more than I had expected. I did also pick up a used Channel Master CM7000 and need to get one of the RCA universal remotes that can be programmed for it - using he S-Video input provides truly superb 480i PQ. Anyway, just saying I was much more impressed with the DTA800B than I expected. These units are quite abundant at thrift stores - the RCA CECBs may have been the best-selling model due to widespread retail availability. Of course, brand-new DTA800B1 boxes can still be purchased at Wal-Mart and Amazon.

Someone else correctly noted that more and more Americans are replacing their SD tube televisions with low-cost HD LCD and LED sets containing built-in ATSC tuners. Those folks are also donating more and more of these digital TV converter boxes. Therefore, used CECBs aren't quite as scarce and pricey on Craigslist as they were a couple of years ago. Hence, my nomination of the RCA boxes as a commonly-available and decent-performing choice.
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post #393 of 416 Old 08-16-2013, 08:53 AM
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Quote:
Originally Posted by seatacboy View Post

I did also pick up a used Channel Master CM7000 and need to get one of the RCA universal remotes that can be programmed for it -

There's a good chance any u-remote you already have will work. If one isn't new enough to have converter box codes you can try the Pioneer cable box code (those have been around a long time). Now there is a mysterious menu function on the CM for Pioneer cable box code on/off which I suspect activates or deactivates that capability but there's no mention of it in the lousy manual.

Yeah the RCAs are everywhere, probably due to Walmart. I think they were sold in several other retail stores as well.

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post #394 of 416 Old 10-22-2013, 08:56 AM
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Quote:
Originally Posted by Floydage View Post

Yeah the RCAs are everywhere, probably due to Walmart. I think they were sold in several other retail stores as well.
Unfortunately like many CECBs, the RCAs were built cheaply with indifferent quality control. If you can get one in working condition, the DTA800-series CECBs are generally quite good compared with some other brands (GE/Sylvania/Magnavox come to mind as less-desirable).

Worth noting: from 2008 through 2009, the DTA 800, DTA800B and DTA800B1 CECBs were licensed by Thomson/RCA for manufacture and distribution by Audiovox.

After the 2009 U.S. analog shutoff, Thomson/RCA sold off the manufacturing and distribution rights to a different company, AVS Multimedia.

AVS Multimedia focused on marketing these converter boxes to Canadians during Canada's digital TV transition, which occurred in August, 2011, two years after the U.S. analog TV shutoff.

The AVS Multimedia-manufactured boxes look identical to the Audiovox-sourced units, but two key features are omitted: the very useful Electronic Program Guide and the Smart Antenna input. Presumably, this was to save a few pennies in royalty costs and a few pennies in manufacturing expense per unit.

AVS Multimedia still makes and distributes the RCA DTA800B1. They are sold at Wal-Mart, Amazon and other sources.

P.S. I just realized that as AVS Multimedia is a Canadian company, the phrase "save a few pennies" is anachronistic as Canada no longer uses the penny!!
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post #395 of 416 Old 10-23-2013, 08:59 AM
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Interesting. Losing the EPG sucks. After having so much trouble with my RCA I bought in the early -90s I'm not much on Thomson; they appear to be a French Canadian firm. I obtained the service bulletins for that RCA and it had a lot of pages, lots of soldering issues. They also did GE and some other 'goodwill' names they acquired (Sylvania and Magnavox?).
Looks like the same kind of thing with the Zinwells I last saw selling on Amazon. Manual didn't show the timer and favorites functions anymore.

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post #396 of 416 Old 02-08-2014, 05:28 PM
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Hello everyone. I own two RCA DTA800B1 boxes and so does my brother. These were purchased in January 2009 using the coupon program available at that time. One of my units is still in the box, unopened. I use one for my TV at home. My brother uses both of his for two TVs at his house.

Sometime around a year ago we each noticed that our boxes would lock up when trying to do either a full new scan for channels, or when doing a scan-add. The lockup happens at about 64% of completion. The green light on the front of the box goes out. The only way to recover is to physically unplug power from it and then power back on. I'd tried letting it sit as long as overnight and it didn't recover.

We had each thought that "it must be these cheap boxes, last only a couple of years and then gone." Well, I'm learning there's a different reason for it.

In web searches for info about "RCA DTA800 scan lockup" I found others had run across this problem. In those cases, they found that if the scan locked up, they could disconnect the antenna from it, and it continued the rest of the scan (with no other channels added). One of the responses said that the problem was with the TV station it was scanning at the time of the lockup, that it was transmitting bad CRC's, and the RCA box just tried over and over to get it. The firmware provides no bailout point to just scratch that channel and continue looking for more.

That's making sense. I'd had a need to do full rescans every so often, since sometimes a channel gets added in (just recently, GetTV, for instance). The scan-add function doesn't add new digital subchannels to an RF channel it already knows about. So, when KFTR that only had channel 46.1 just added GetTV on 46.2, the only way to get 46.2 in there is to do a new full scan rather than scan-add on this device.

To keep it from locking up, I kept my finger on the Menu button on the remote during the scan, watching that percentage on screen go higher and higher, and when it got to 63% I hit the button and stopped it there. That's been able to get me the new channels I was looking for, but at the expense of any channels higher up on the RF channel spectrum. I suppose I can do what some other folks found, unplug and replug the antenna connector briefly and let it finish the scan.

What channels am I obviously missing? A number of channels on KJLA virtual 57.x (RF 49), and one of the PBS stations here in Los Angeles, KOCE on virtual 50.x, which is on RF 48. And RF 48 seems about right for being 64% of the way through the scannable spectrum. RabbitEars.info lists only a couple of stations on RF channels above 48 for this area (http://www.rabbitears.info/market.php) so I'm not missing out on too much from stopping the scan early.

It's looking very much, from purely circumstantial evidence, that if there's a station transmitting bad CRCs, that it's probably KOCE. Here is why I think so. The RCA box has an occasional glitch, when I am going through the channels one by one using the channel up or down button, on channel 50.1 it drops all audio and the control doesn't do a thing. Then anywhere from 20-60 seconds later, it jumps up a couple of channels (like it had the pending channel change command in buffer) and all is well again. And this only happens at KOCE 50.1, and like I said only occasionally.

The only reason KOCE is in my brother's two boxes is that he has not done a full rescan. KOCE was added way way back, presumably before they started transmitting bad CRCs. He does not wish to lose that channel, and does not feel it's worth doing a full rescan to get a couple of subs he doesn't have if it's going to mean losing KOCE.

If the problem lies with KOCE as I suspect, how can we prove it so that the station engineer can be informed about specifically what needs to be fixed? It probably requires special ATSC scanning hardware we consumers don't generally have access to.

A lot of people won't run into this issue; the stations in your area might be putting out fine data. Others may have decided the box went out, and got some other brand which doesn't have that issue, or went to a regular HDTV and don't even use a converter box anymore. But for anyone who has run into the channel scan lockup, try unplugging the antenna for a moment and right back in, and at least you'll get some of the channels.
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post #397 of 416 Old 02-09-2014, 08:51 AM
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Me, I'd do a factory reset and start from scratch. I suspect some old station data is stuck in there and is cross-mapping to their new data (ideally the station should clear this out but...). Don't be afraid to contact the station with the above info. I kept having a transmit power problem with my local Fox station here which they claimed wasn't at their end - a few weeks later I get a BTW email saying the electric utility found a bad feed-line to one of their power amps.

If that station is still a problem I'd try deleting it and even doing a manual scan for that RF channel (and any other cross-mapped RF channel if supposed to be unused) with the antenna disconnected, that is if this box is capable of single channel manual scanning.

Beyond that, manually scanning each desired RF channel from scratch after a factory reset.

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post #398 of 416 Old 02-09-2014, 02:39 PM
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Thanks for the suggestions. You can't manually add or delete a channel on this. You can skip it from the lineup but it'll still appear in the program listings. I'll try the factory reset and see if it'll complete a full scan without an antenna connected. If that works but it won't do it when connected then it's pretty good evidence that it's a station signal doing this.
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post #399 of 416 Old 02-10-2014, 08:37 AM
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But then again if you do a factory reset there won't be any old channel data to muck it up, assuming that's the problem. Still a good set of experiments to narrow it down.

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post #400 of 416 Old 02-11-2014, 08:41 PM
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OK. Here's what I tried. Full reset using menu, then unplugged it completely for a few minutes. Hooked it back up and, with antenna disconnected, ran a channel scan. It went all the way through and found nothing - but it didn't lock up.

Reconnected antenna and did another scan. Locked up at 69%. Disconnecting and reconnecting antenna didn't help.

Had to unplug and replug power. Did a scan once more but stopped it when it reached 68%. 126 channels, but no KOCE. I'm going to live with what I've got.
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post #401 of 416 Old 02-12-2014, 08:58 AM
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I don't think it will matter at this point but did you do a Full reset and then scan with antenna hooked up? (i.e. without the disconnected antenna scan/step in between).

If that doesn't matter then it does sound like the station, although I'm suspicious that these boxes lack the capability of overcoming this scenario (whether it be a software design flaw or a latent issue). What happens with another brand of tuner or a TV with built-in tuner if you have any to try? (or local friends and neighbors).

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post #402 of 416 Old 02-20-2014, 12:24 PM
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After using and evaluating several of these converter boxes - acquired used at thrift stores - my observation is that the DTA800 series (at least the pre-2010 models) have pretty darned good tuner sensitivity and are pretty easy to use. In connecting several converter boxes to roof-mounted CM4228HD antenna, the DTA800B picked up as many stations as the Zenith DTT900. The signal-strength meter on the RCA is much more conservative than what's on the Zenith or Channel Master boxes, it is almost impossible to get a signal strength reading above 75% although the Zenith can get up to 90% and on several channels the CM shows at 100%. Curiously, even at high signal strength levels, there is periodic break-up possibly due to multipath - i.e. nearby trees swaying during high winds.

One weird thing I noticed on mine, though: at some times, the displayed 480i picture seems to subtly drift in-and-out of focus. It is somewhat distracting. Is this perhaps a symptom of a problem with the power supply or capacitors? Are there known "fixes"? This happens to be a nice converter box for a bedroom SD television because of the big-button remote.
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post #403 of 416 Old 02-20-2014, 04:17 PM
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That's a weird one (focus). Did you try other boxes? Other source than OTA?

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post #404 of 416 Old 02-22-2014, 01:57 PM
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Quote:
Originally Posted by Floydage View Post

That's a weird one (focus). Did you try other boxes? Other source than OTA?
Yes, I have tried four other converter boxes. The DTA800B is the only one exhibiting these symptoms of "drifting in-and-out of focus". It occurs in the middle of the screen, and it's noticeable. This may only be a minor flaw in my DTA800B. Since I have other boxes (the Zenith DTT900 and its Insignia counterpart, a Channel Master CM7000, a Zinwell (minus remote), a Magnavox and an Apex), it's not a great loss.

At some point, I will sell off the CM, Zinwell, Magnavox and Apex or even give them to a needy person. I have four of the LG/Zenith/Insignia boxes and they are generally satisfactory although they do lack the S-Video functionality. I might sell off or give away the RCA as well.
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post #405 of 416 Old 02-22-2014, 03:02 PM
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I'd a thought that RCA with the weird problem would be the first to go. smile.gif

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post #406 of 416 Old 05-26-2014, 04:04 PM
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Quote:
Originally Posted by Floydage View Post

I'd a thought that RCA with the weird problem would be the first to go. smile.gif
Oddly enough, the "drifting in-and-out-of-focus" problem only occurs with one local TV station, KOMO (RF 38). My wife insists on keeping our 7-year-old Samsung HD CRT, even though its now-deceased built-in ATSC tuner requires use of a converter box. Since she primarily watches the non-HD Create and Live-Well networks on that set, I haven't bothered buying an HD box for that set like the iView. My late-2008 DTA800B actually has been very dependable, and she likes the big-button remote. If I want to view HD content, I use the LED HD set in the second bedroom.

The RCA box we possess has been reliable, tuner quality is very good, and the picture quality satisfactory for 480i. These were probably the best-selling of the CECBs and can be bought used very cheaply.
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post #407 of 416 Old 05-26-2014, 04:10 PM
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Quote:
Originally Posted by Whidbey View Post

From amazon.com's description of the RCS DTA800: "Includes SmartAntenna interface for separately purchased antenna that can be electronically controlled by the DTA800" What's that all about? I did quick google of "SmartAntenna interface" and didn't come up with much. IMHO, the only smart thing a new converter box could do is rotate my antenna for me. James
It's hard to believe that the RCA Victor CECB, actually made by RCA's licensee Audiovox, was showing up for sale on Amazon way back in November, 2007. That was six and one-half years ago! However, in 2010 RCA licensing sold the manufacturing rights to this design to a Canadian company called AVC Multimedia. Although the "new" DTA800B1 appears identical, ncluding the "big-button" remote, AVC Multimedia deleted some features of the original Audiovox RCA boxes, like the Smart Antenna input and the rather nice Electronic Program Guide. I'm unsure if the quality and reliability of the AVC boxes are any better or worse than the Audiovox units of 2007-2009.
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post #408 of 416 Old 05-27-2014, 09:37 AM
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Quote:
Originally Posted by seatacboy View Post

Oddly enough, the "drifting in-and-out-of-focus" problem only occurs with one local TV station, KOMO (RF 38).

I see. Sounds like one of those station issues where old station data is stored in the box and needs to be purged, usually via factory reset, etc. Unless the station is just sending out mixed signals that RCAs are susceptible too unlike the other boxes.

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post #409 of 416 Old 09-13-2014, 01:11 PM
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Doing another project, I learned how to dump the serial flash chips such as used in this box (25l4005 is a 512Kbyte 8 pin serial flash). Now I have something to take apart and look at. Seems much of the hardware code is easy to get to , the main software and menu system is zlib compressed. All is mipsl format and not that hard to disassemble.


One interesting part is that at the end of the flash is the channel info. It has virtual channel number, real ch number (in an odd format but it is there), ch PID and Unicode string for the channel name. In my dump of the flash there were a number of channels that were not displayed on the channel list, but you could enter the ch number and go to that saved but not visible channel. Seems the channel scan is a bit more like an append that it seems. Might not be true on newer Broadcom based DTA800's but seems true for the one I have. The strings in the file suggest that the scan was designed to be either replace or append even with the 4.0.8 version even if the sw did not implement it.
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post #410 of 416 Old 09-14-2014, 08:14 AM
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Maybe a Favorites list? In any any event I think most boxes retain the consumer deleted channel info in the background.

Now maybe your one who could modify it to display a nice multi-day EPG?

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post #411 of 416 Old 09-14-2014, 12:55 PM
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Might be able to dump the EPG out the serial port, but not sure if I could teach it to display it on-screen.


I have managed to dump flash contents out the serial port and the 1st Meg of the RAM. I used the #4 option on the serial port menu system that lets you send binary to the box for execution at RAM 0x80016000 (the place it puts compressed data main usually so it overwrites the first few lines of that--not a biggie as you have to reset the box after the dump anyway). You have to use XModem protocol and I just use Hyperterm for that, so I put in a 15 second or so loop at the start of the code to give me time to shut down Hyperterm and start up RealTerm to do the binary capture of the dumped info. Here is the code I used for the flash dump:

FF 50 11 3C FF FF 31 26-FE FF 21 06 00 00 00 00
C0 9F 10 3C 08 00 11 3C-00 00 04 92 40 B0 08 3C
80 01 08 35 01 00 0A 24-18 00 09 81 24 48 2A 01
FD FF 2A 15 00 00 00 00-1C 00 04 A1 01 00 10 26
FF FF 31 26 F4 FF 21 06-00 00 00 00 FF FF 00 10
00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00


Not much to it. It uses a direct write to serial register to do the serial write and there is a delay while it tests if status register is ready for another write. About 1 minute per meg at the 115.2Kbaud that serial port is set at.


I just use a pair of transistors to do the box-PC interface. 2n3904 with 10K on the bases and 2.2k pull up resistors on the collectors. Emitters grounded. Tx lines go to the base resistor and RX lines to the collector/pullup. I've found anything from 3V to 6V works OK on my PC and I haven't blown anything in the RCA box as of yet, but I use between 3.5 and 4V typically.
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post #412 of 416 Old 09-14-2014, 04:16 PM
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Nice work! Hey that's a good start for any number of projects.

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post #413 of 416 Old 09-15-2014, 09:26 AM
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I hope so!
I've been playing with using the #4 option to load code that overwrites code n RAM in ways to help me figure out stuff and have had some good results. Even tried one that overwrote the code so that at one point I could call to routine that was part of the binary I loaded (I wanted to know how the remote buttons were represented in the code and now I know).

For stuff like the above though you need to have disassembled the box's code to know what you are doing. With the flash dump code I think it should work with no knowledge of the box--it just has to have the same serial port registers.
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post #414 of 416 Old 09-15-2014, 03:48 PM
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Trying to do some kind of universal remote project? Any other project(s) in mind? A good learning experience nonetheless.

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post #415 of 416 Old 09-16-2014, 09:38 AM
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My goal in the first place was to get the box to send out signal strength info so I could figure out what channels would be good at a translator facility.

I was trying to figure out how the front buttons were read yesterday and found
Quote:
read of b0400704 gives 80b w/ no button down
809 w/ power button
819 w/ch-
829 w/ch+
81b w/power and ch-
82b w/power and ch+
839 w/ all buttons down
And I had know for some time that if you held down power and ch+ that a message came out the serial port:
Start XModem download of compressed binary..

which is just about what you get with option 5 on the serial menu but that option adds "RAM" just before binary. I had not picked up on that.
When I looked at what power and ch+ gives you, I found that it decompresses the zlib and erases flash (sending out "#\r\n" every 4k sector of the flash) then programs the flash (sending "+\r\n" with every sector I think), verifies the write (you might get "=\r\n" with every sector or it might be more often--I'm not sure). If the verify fails the erase/program/verify sequence is tried again and you either get a "Done" or "Verify failed" message.

So, it seems we have a way to dump flash and write a new image to flash.

BTW, most every setting you put in box is saved around 0x7c000 in the flash (Password at7c01c )
Quote:
07C010 00 00 00 00 00 00 10 C8-00 01 00 00 01 02 03 04
shows you password 1234 as the numbered keys are just represented as 0x00 to 0x09 in the code.
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post #416 of 416 Old 09-18-2014, 10:07 AM
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BTW, it does not look like one needs to learn to write flash to modify user data or channel list. It gets copied to RAM and you can change it there with a little code, then make the box back up that data with just a press or two on the remote (if you don't overwrite part of the code that the box needs to keep running).
The same code that dumps flash can dump RAM, just change the starting addr and length of dump it does.
In my older DTA800B the data gets put at 0x80084c90, so doing a dump of the first megabyte would be plenty rather than do the whole 16meg of RAM.
I have noticed that I can do a RAM dump and continue to watch TV just fine. The speed at which I get data is slowed to about 1 meg every two minutes rather than the 1 minute that I posted earlier. I've even entered a routine that I can execute by just going to the signal meter screen and then back out and watch TV till I want to do a dump again--the screen freezes till the dump is done, but then everything is good again.
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