VBox eeprom

[bpalone]

I can't take any credit for this, just found a post about it on another site. Thought it might be of interest to some of the folks around here. The link provides information on cloning the eeprom in V Box positioner:

https://sites.google.com/site/railworks30/vbox7-eeprom

 

[KE4EST]

Great info and thanks for sharing! Love the part and the code for cloning an EEPROM!

I will note that most likely this guy just had a bad EEPROM chip. He states "due to constant rewrite of current position". Unless he was constantly changing the clamps on his dish or something, there is no constant rewrite of the current position. This is often a misconception about EEPROM chips. Reading the chip is not the same as writing. You can perform many, many more reads than you can erase/writes.
When you move your dish to a certain position when you are first setting it up and hit save, that is a write. No one changes their dish parts around that much, that they are constantly, daily writing. Even if he did 100 writes a week it would take 19 years to hit 100K writes. Just telling your dish to go to 99W for example and the vBox looks up what 99W is...this is just a read.
Being though how an EEPROM works internally, it is most likely that they got the cheapest ones they could find and the manufacturing process, made them not to be the best EEPROM. Also it could have been as simple as a cold solder joint and changing out the EEPROM chip fixed that.
Going a step further according to the data sheet on that chip, if done right, it should have 1,000,000 erase/write cycles before data corruption; it also has a data retention rate of >200 years... So you can do the math on that.

 

[Lone Gunman]

Say KE4EST, I remember a few months back when we were doing repairs on those Vboxes I have that one or two of those weren't fixed with the chip replacement I did?? Is this something that a lightning strike could also hork up?

I've got one that has a count issue and another that won't do much of anything?

 

[KE4EST]

Yes, it is possible. Pull yours out and see which chip they use for the EEPROM.
It will be the small eight leg chip. I have seen different ones used.

 

[Lone Gunman]

These numbers are on the one in the Vbox X that won't do much of anything. The one that the count function is horked up in is also a Vbox X so I'm going to "assume" it's the same number.

HT93LC66

A949G0301#7

 

[KE4EST]

Here is the one you need:
http://www.ebay.com/itm/10-PCS-93LC...644178?hash=item1c67af93d2:g:muEAAOSw7PBTotEG

 

[Lone Gunman]

You're kidding right? Did you forget who you were trading messages with? I got no clue about that stuff in the drawing or the picture??

I did notice this at the end though where he says:

Installing a blank eeprom at failure also works, but requires reprogramming via the receiver.

So does that mean it can be programmed by my Micro HD and if so, exactly how is that done??

 

[KE4EST]

So does that mean it can be programmed by my Micro HD and if so, exactly how is that done??

Just like you would do if you had a new vbox.

 

[Grimgnaw]

Great info and thanks for sharing! Love the part and the code for cloning an EEPROM!

I will note that most likely this guy just had a bad EEPROM chip. He states "due to constant rewrite of current position". Unless he was constantly changing the clamps on his dish or something, there is no constant rewrite of the current position. This is often a misconception about EEPROM chips. Reading the chip is not the same as writing. You can perform many, many more reads than you can erase/writes.
When you move your dish to a certain position when you are first setting it up and hit save, that is a write. No one changes their dish parts around that much, that they are constantly, daily writing. Even if he did 100 writes a week it would take 19 years to hit 100K writes. Just telling your dish to go to 99W for example and the vBox looks up what 99W is...this is just a read.
Being though how an EEPROM works internally, it is most likely that they got the cheapest ones they could find and the manufacturing process, made them not to be the best EEPROM. Also it could have been as simple as a cold solder joint and changing out the EEPROM chip fixed that.
Going a step further according to the data sheet on that chip, if done right, it should have 1,000,000 erase/write cycles before data corruption; it also has a data retention rate of >200 years... So you can do the math on that.

Granted, each receiver SAVE simply records a satellite position, and, yes, that is not done very often, but, each time the dish is moved the VBOX keeps track of current position and from our information by observation that is recorded in bytes 246 and 247 of the 256 available bytes on the eeprom. This writing of current position has to be accomplished each time the dish is moved.

As evidence of current position retention one can unplug the VBOX and then plug it back in and the VBOX does not lose the current position. If there is other nonvolatile memory on board the VBOX it would be of interest to know where it is, as I have the list of chips on its board, and none qualify unless the cpu has something not mentioned in its spec sheet or that I have missed.

 

[Grimgnaw]

Here is the one you need:
http://www.ebay.com/itm/10-PCS-93LC...644178?hash=item1c67af93d2:g:muEAAOSw7PBTotEG

The chip referenced above is the one used in the VBOXII, not in the VBOX7.

To get the spec sheet (or a seller) for that used in the VBOX7 Google (or Ebay) search for L24C02B or 24LC02B.

 

[KE4EST]

The chip referenced above is the one used in the VBOXII, not in the VBOX7.

To get the spec sheet (or a seller) for that used in the VBOX7 Google (or Ebay) search for L24C02B or 24LC02B.

You are correct for most of the 7's. I have seen where some of the clones use different ones. I chose that one because that is what Lone Gunman has in his unit. He has different ones, also.

 

[Lone Gunman]

The Vbox X I mentioned up the page works/functions just like the Vbox II, which is "somewhat" different from the Vbox 7s so that one is the one I would need.

 

[Grimgnaw]

Granted, each receiver SAVE simply records a satellite position, and, yes, that is not done very often, but, each time the dish is moved the VBOX keeps track of current position and from our information by observation that is recorded in bytes 246 and 247 of the 256 available bytes on the eeprom. This writing of current position has to be accomplished each time the dish is moved.

As evidence of current position retention one can unplug the VBOX and then plug it back in and the VBOX does not lose the current position. If there is other nonvolatile memory on board the VBOX it would be of interest to know where it is, as I have the list of chips on its board, and none qualify unless the cpu has something not mentioned in its spec sheet or that I have missed.

With regard to the number of writes to the eeprom, it is even greater than I inferred earlier, i.e., "This writing of current position has to be accomplished each time the dish is moved" and my meaning was it writes to the eeprom only after each stop. Not so!

As a result of this discussion my friend Randy ran a test where he instructed the dish to move from display position 500 to 1500, and unplugged the VBOX at about half way before it reached the 1500. The results showed that it had been writing to the eeprom continuously during the move, and when plugged back in remained at the position it left off at (requiring further instruction to continue to 1500). Thus, the number of byte writes to the eeprom of current position are huge.

My first VBOX7 was purchased in Jan or Feb of 2014, thus, the eeprom lasted about 38 months before it began losing counts.

 

[KE4EST]

You are exactly right and I had forgot about that when I made my above post. I work a lot with micro-controllers and see a lot of where people mistakenly think reads count toward the death of an EEPROM as well.
I designed and built my own dish mover about 3 years ago and in fact added that to mine also. It does write to the EEPROM every time the dish is moved the current position. It got me to thinking though, I haven't looked at my code in a long time.

I seem to remember that I had it check time and only write to EEPROM if the current position had changed after a certain time. So I got curious and just went back through the code just to see what I had done.
I did have a timer set. There is currently a function that gets flagged to be called if the dish position changes. So what it does is then go and check to see what the position is hold it in a temporary RAM location, and then check again in 5000 milliseconds. If the last position is the same as 5000 m/s later it will then and only then write to the EEPROM. This function gets fired only during dish moves and if it is a long move and it checks and the current position is different from last check(i.e. the dish is still moving) it resets and checks again in 5 seconds. It will only write to EEPROM if it is satisfied the dish has stopped. Of course I done this to save wear and tear on the EEPROM, and I have never had a problem.

However, I have never, to my knowledge had the power go out during a dish move. I can see where this would be a problem if the power failed during a move and then things would totally be wrong when power was restored.
I should probably have it continuously writing to EEPROM. If I modify the code and do this, however I will have it also programmed to move to a new location in EEPROM every 100K writes. The EEPROM I used it way over kill but I have several of them so that is why I chose that chip. IIRC it has a 512Kbit chip so I have plenty of room to move the storage location of current position ever so often. 64k will take awhile to go through.

 

[KE4EST]

IIRC it has a 512Kbit chip

Yep, 24LC512