Products > Test Equipment
Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
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garrettm:

--- Quote from: joeqsmith on February 07, 2021, 10:55:04 pm ---[...]
I started to look at the TL866CS programmer.  It's cheap enough but after seeing the comment about reading the parts three times to make sure they are right and then there were several posts about the company having malware in their software.   But, then again, you get all these crazy adapters and such for under $100.  What's been your experience with it?

--- End quote ---

I like to verify each step of the process since I tend to be overly cautious. I would hate to upload something that ended up wasting people's time... So that comment of mine wasn't intended to sound like an implied failing of the TL866II, but rather that I didn't mess something up while copying the contents of the ROMs. Even if I had a 1000 dollar programmer, I would have still checked for consistent results before uploading the ROM dumps for others to use.

I picked up my TL866II Plus for only $30 off eBay new. But it can't do higher than 18V peak programming voltage, so the older 2764s are unable to be programmed using it. The TL866CS or A models however can do the required 21V and should be found for less than $50 buy-it-now without any sockets/adapters. You need to be careful to avoid getting a TL866II since the CS and A models are discontinued (but still useful to have for programming older EPROMs).

The major issue with the CS and A model programmers was China being China, i.e. it was cloned. This lead to bricked units during firmware updates. I found the whole situation ironic. For everyone else, it was a shit-show that led to the development of open source software and firmware that is compatible with the original and cloned TL866CS/A/II programmers.
garrettm:

--- Quote from: joeqsmith on February 08, 2021, 02:35:06 am ---[...]
40 ASCII character readings per second would be 2.8 readings a second with 14 characters but I was seeing data much faster than this.   It's odd they would use the term Readings as they defined that to mean display updates in the manual.   I wouldn't be surprised it they turn off the display in these high speed modes.    Still, I don't buy it.  The reason is because I never see the sync running that fast with no data being transferred.   Then again, maybe reading in this context is that rate the ADC is making decisions, not how fast the display is being updated.
[...]

--- End quote ---

I interpret "ASCII character readings" to mean one 6.5 digit reading sent via a 13-character string with <CR><LF>  tacked on for a total of 15 chars per "reading". Although, this rate could require command J to suppress <LF>, reducing to 14 chars per reading.
SilverSolder:
The way VirusTotal works is they have ~50 scanners that are all "polled" about their opinion about a particular piece of software that is uploaded to the VirusTotal site.  Some of those scanners are better than others, and pretty much all of them can be provoked into false positives depending on the type of code being uploaded.  Getting just a handful of positives is not really a sign of "sure fire danger",  but I would be concerned if - say - more than half the scanners think there's something wrong.  In that case, I might install the software in a virtual machine first, to keep things contained.

This time I just created a restore point, then installed the software, so I had a way to roll back if something went wrong.

I opened the TL866CS up, it actually seems quite well made inside.  The socket on mine is marked "Aries" and feels solid enough, better than expected.  It is a black socket, not the green one I see on most pictures.  I guess one could always modify one of these with a real 3M part, but that might cost half as much again as the whole programmer!  :)



SilverSolder:
Re binary mode:  3 bytes is enough for an ADC reading (21 bits plus a sign bit). 

It seems the 500 readings per second literally consists of taking an ADC reading and pumping it out on the interface, with no processing at all!

If we can get that to work, we could do the averaging externally as discussed.


[Edit]  3 bytes times 500 readings per second is 1500 bytes per second, probably requiring a min baud rate of something like 19,200 to transmit?   I don't think 9,600 sounds enough?
garrettm:

--- Quote from: SilverSolder on February 08, 2021, 02:58:59 am ---Re binary mode:  3 bytes is enough for an ADC reading (21 bits plus a sign bit). 

It seems the 500 readings per second literally consists of taking an ADC reading and pumping it out on the interface, with no processing at all!

If we can get that to work, we could do the averaging externally as discussed.


[Edit]  3 bytes times 500 readings per second is 1500 bytes per second, probably requiring a min baud rate of something like 19,200 to transmit?   I don't think 9,600 sounds enough?

--- End quote ---

I like the idea of taking the raw output from the ADC. Though doing all the math (cal corrections, scaling, offset, etc.) makes it a bit of a challenge to get the actual reading, but it might be worth it for the increased sampling speed.

A 3-byte binary payload with <CR><LF> termination gives 5-bytes per reading. Assuming 8N1 serial frames, that’s 10 bits per byte. So 5[bytes/reading]*10[bits/byte]*500[readings/s] = 25000 bits per second minimum. So a modded Bit Serial Interface module with 19200 baud could in theory transmit 384 readings/s.

Assuming Fluke's specifications aren't a broken promise, I think we have a new eevblog forum challenge! Who can get their 8505/6A to read the fastest! Bonus points awarded for achieving 500 readings/s.
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