Electronics > Repair
Advantest R6581 VFD replacement
IanJ:
Anyone got a source of R6581 compatible PCMCIA cards?
I have a working 1mb SRAM card, but it only shows up at around 60k free after initialize (integer overflow maybe?)…….plus it doesn’t have an integral battery.
What’s the R6581 max size?
All the Flash type cards I have don’t work or show up as a lot less than 60k.
Presume the interface is PCMCIA II and not III.
Ian
chekhov:
--- Quote from: IanJ on December 17, 2024, 02:10:00 pm ---LCD & LT7680A-R (c/w flat flex & FPC conn) = https://www.buydisplay.com/bar-type-4-58-inch-320x960-ips-tft-lcd-display-spi-rgb-interface
Ian.
--- End quote ---
Be aware that they only sell those LT7680A-R-based boards together with TFT displays, one for each, refused to sell separately.
IanJ:
--- Quote from: chekhov on December 26, 2024, 10:50:18 am ---
--- Quote from: IanJ on December 17, 2024, 02:10:00 pm ---LCD & LT7680A-R (c/w flat flex & FPC conn) = https://www.buydisplay.com/bar-type-4-58-inch-320x960-ips-tft-lcd-display-spi-rgb-interface
Ian.
--- End quote ---
Be aware that they only sell those LT7680A-R-based boards together with TFT displays, one for each, refused to sell separately.
--- End quote ---
Yes, I did email them also and ask if they could release the boards separately, but they declined...........I was wanting some spare.
Luckily, it's quite an inexpensive kit considering.....
PS. I have updated my source/.HEX on GIT, now handles more OHM symbols on the AUX line......I found one line where there are 5off them (CONFIGURE, 2W or 4W, RANGE-LIMIT, LOWER-LIMIT).
Also found a couple of other symbol characters I missed.
Ian.
IanJ:
Hi all,
I have made some mods to my TFT implementation of the display.
MOD. 1 - 9th Jan '25
I have always wanted a 1 VDC range for the R6581. Now, we do get a 1000 mV range however I guess I am too used to my 3458A where it will display X.XXXXXXX VDC.
So, I added a new mode whereby if you are on the 1000mV Range and you hit the DCV button it will switch the display out to a new 1 V Range.
It gets its data from the 1000 mV Range and so you get an extra digit, one more than the 10 V Range for instance at max 8.5 digits.
See photo below.
The Blue Pill uses two additional inputs to interface to the DCV button, see photo below.
Two are required because the button is multiplexed and I need two inputs to somewhat read a button press.
GIT source = https://github.com/Ian-Johnston/R6581_VS_Display
GIT .HEX file = https://github.com/Ian-Johnston/R6581_VS_Display/tree/master/VisualGDB/Debug
Only upgrade to this version is you hook up the new inputs to the DCV switch.
New Pcb gerbers attached which include the new A11/A12 connections.
Any issues then let me know (there are a couple of very small things).
PS. For the coders, The Blue Pill doesn't have a hardware FP and the software FP was being a pain, i.e. I wanted to use atof but it just continued to return empty, so I wrote around it (ugghh!). There doesn't seem to be any downsides though. I’ll return to this soon as atof is a lot less code.
UPDATE - 9th Jan '25
Digital input A11/A12 logic tweaked.
UPDATE - 10th Jan '25
1 VDC mode is now quite a bit more seemless, once it is set then it will remain in 1 VDC mode even if overrange or the DMM is in AUTO mode.
GIT hex file updated.
Still to do: try to reverse engineer the keypad better to fully isolate that button.
UPDATE - 15th Jan '25
Vertical Back Porch for TFT set to 11 rather than 10 (10 is per spec!) due to TFT flickering issue when running the R6581T for 20hrs.
Possibly the a heat/stability issue with the LT7680A-R or the TFT itself. They do run pretty warm in there (I might look at a fan upgrade)!
UPDATE - 16th Jan '25
Horizontal Back Porch for TFT set to 30 rather than 20 (20 is per spec!) due to TFT still flickering issue when running the R6581T for 12hrs.
I have attached the original HEX file and this new one.
UPDATE - 19th Jan '25
Fix issue where random pixels might appear at right hand vertical edge.
See new HEX file.
MOD. 2 - 10th Jan '25
When the LCD shows "DISPLAY OFF" i.e. when the user actions this via the menu, it now turns off the LCD completely (blank). Pressing the MENU button revives.
It reduces the backlight to minimum, and turns off the LCD via register 0x12 of the LT7680.
A user asked for this and I guess it's good for TFT long term saving especially for those running the DMM 24/7.
UPDATE - 12th Jan '25
Bug fix on the backlighting brightness control when implementing DISPLAY OFF.
Ian.
kt6ln:
I made the conversion of my R6581T to Ian's TFT screen type.
First many thanks to Mickle T. who started this journey with OLED display and then to Ian updating it to TFT. I am lucky to have benefited from both of their efforts to have a beautiful R6581T screen. I could not have made it alone.
I kept in contact with Ian across the pond since his first PDVS (first gen) reference. He has been very helpful over the email frequencies! ;) And we are still in email exchange to perfect the behaviour of the TFT screen for this application. He made the conversion process easy. If I can do it, everyone can, also.
If you were wondering who the heck I am, I am a silent voltnut with a few 8½ digit multimeters in his arsenal. I call "silent" because I never posted anything on EEVblog before. But now, I feel compelled to write and encourage all voltnuts out there who also own R6581T. Try Ian's update if you have not done it already. If you follow his written instructions and video, you should have no problems.
ismail
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