EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: Smile2016 on November 04, 2024, 09:34:35 pm
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Does anyone have info, solution or ideas on an LCD or OLED retrofit for PM6690 frequency counter? The original display is a 320x97 pixel graphical LCD with an LED backlight, model TM32097AGFG.
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https://www.eevblog.com/forum/testgear/new-display-for-pendulum-cnt-90-counter/ (https://www.eevblog.com/forum/testgear/new-display-for-pendulum-cnt-90-counter/)
its a 320*97 pixels lcd, but no one so far has the right substitute ... some saw a few things with a 320*64 ... but for sure misses 33 lines ...
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Or use a 320x128 display leaving two unused black bands above and below, provided that the dimensions of the new display are compatible.
In addition, you need to interpose a micro or an FPGA that converts the signals from the old display to the new one: in short, a lot of work.
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you have to check in the service manual for the pinout ... cant find anything on this model ... ?
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The schematics can be found at this link. https://assets.fluke.com/manuals/6690____smeng0000.pdf . I’m curious if anyone has already put in the time and effort to create something similar. The biggest challenge is finding a display that fits mechanically in the available space. I agree that an FPGA or MCU might be necessary, along with extensive data capture experiments. It’s unlikely to find a display with the same driver chip, which is currently unknown...
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best luck would be to find this lcd controller driver chip(s) and see what subs we can find
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320x96 pixels... this might suggest a dual 65 x 132 (192) Dot Matrix LCD Controller, such as the ST7567 ST7539 or so . It appears that only D0 to D3 are in use, while D4 to D7 are grounded, suggesting that the SPI 4-wire mode is likely selected? The option setting MD J2.6 is set to low (“L”), which could correspond to PSB being “L” in the ST7567. Time to connect a logic analyzer and verify! V1..V5 biasing is fixed and similar to ST7567 datasheet. https://www.hotlcd.com/upload/download/ST7567_V1.0a_080220.pdf (https://www.hotlcd.com/upload/download/ST7567_V1.0a_080220.pdf)
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do you have an counter dismantled and show us some pcb pictures of the original lcd ??? ic's markings
it was never shown here, just numbers ... please please thks
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I don't have such a nice frequency counter but looking at the schematic the type off LCD is mostly controller less. That means it typically only has the LCD driver shift registers and an external display controller. The controller than needs to refresh it permanently like larger TFT displays with a RGB interface.
So XCK is the shiftregister clock (4-8MHZ?), LP should be the Line pulse for latching and FR is the frame mark, and EIO not sure about that. LCD Drivers could be NT7701/NT7702
But without seeing an actual image or some measurements its mostly guesswork.
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do you have an counter dismantled and show us some pcb pictures of the original lcd ??? ic's markings
it was never shown here, just numbers ... please please
Sure, I'll share something over the weekend.
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I don't have such a nice frequency counter but looking at the schematic the type off LCD is mostly controller less. That means it typically only has the LCD driver shift registers and an external display controller. The controller than needs to refresh it permanently like larger TFT displays with a RGB interface.
So XCK is the shiftregister clock (4-8MHZ?), LP should be the Line pulse for latching and FR is the frame mark, and EIO not sure about that. LCD Drivers could be NT7701/NT7702
But without seeing an actual image or some measurements its mostly guesswork.
That sounds like a solid hypothesis. I'll take some signal measurements and share the results.
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some pictures..1.
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some pictures..2.
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some pictures..3.
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a 2005 era lcd .... dang cant find anything on the web
the nearest i can find are 120x320 pixels something like COM33T3N71ZLC ?? spi driven ...
https://www.panelook.com/COM33T3N71ZLC_Ortustech_3.3_LCM_overview_17294.html (https://www.panelook.com/COM33T3N71ZLC_Ortustech_3.3_LCM_overview_17294.html)
can you measure diagonally and or width lenght ... thks
you do have some search possibilities here :
https://www.panelook.com/modelsearch.php?op=size (https://www.panelook.com/modelsearch.php?op=size)
https://www.panelook.com/modelsearch.php?op=resolution (https://www.panelook.com/modelsearch.php?op=resolution)
320x96 pixels search give theses
https://www.panelook.com/resmodlist.php?resolutions[]=21150 (https://www.panelook.com/resmodlist.php?resolutions) all in the +/- 4.2 to 4.9 "
some are in the 2005 era, and discontinued .... :(
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can you measure diagonally and or width lenght ... thks
The opening is roughly 124 x 39 mm, and aligns with the display's active area. The display’s full dimensions are about 135 x 51 mm, with one corner missing, for a mounting screw. From the inside, there is approximately 2 to 2.5 mm of space around the opening, except on the north and west sides, where two CoG controllers (2N, 1W) are positioned with individual FPC cables connecting to each. Display is attached to PCBa by 4 solder joints that powers the LED backlight bars.
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The only mechanically compatible display I found is a 4.58" Rectangle Bar RGB TTL TFT Display (320x960 pixels) - HD458002C40. This could potentially work with the Adafruit Qualia ESP32-S3 for TTL RGB-666 displays. However, a key limitation is the Qualia’s available I/O [they use a GPIO expander on I2C] , mainly supports one native I2C,challenges the data serialization and timing. A 1:3 scaling approach might work, with a few lines repeated to keep the aspect ratio. I’ll get the data format and clocking in more detail later. A Raspberry Pi faces similar GPIO count limitations. Reducing the RGB bit depth, to free up some IOs could help, but my software skills for modifying existing libraries are low..
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I don't have such a nice frequency counter but looking at the schematic the type off LCD is mostly controller less. That means it typically only has the LCD driver shift registers and an external display controller. The controller than needs to refresh it permanently like larger TFT displays with a RGB interface.
So XCK is the shiftregister clock (4-8MHZ?), LP should be the Line pulse for latching and FR is the frame mark, and EIO not sure about that. LCD Drivers could be NT7701/NT7702
But without seeing an actual image or some measurements its mostly guesswork.
very close ! Here are some captured wave-forms. Control signals shown are: FR, EIO, XCK, and LP. In the last 2 pictures, the signals are Data0, EIO, XCK, and LP. The clock is bursts of 80 pulses at approximately 833 kHz. The FR rate is 38.3725 Hz. Data is clocked in on the falling edge of XCK. Maybe the Qualia ESP32-S3+TFT Display - 4.58" 320x960 might still stand..
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its a matter of decoding / understanding all of this, and create the needed interface, mcu based, fpga based etc ....
find an lcd who can decode that ? or if they are controller less ...
there was / is some project here for the 34401a made by qu1ck ... i helped him when i had some 34401a.... and others for hp stuff ...
https://www.eevblog.com/forum/testgear/hp3548-hp3457-oled-display/ (https://www.eevblog.com/forum/testgear/hp3548-hp3457-oled-display/)
https://www.eevblog.com/forum/repair/hp-34401a-dmm-with-leaking-segments/ (https://www.eevblog.com/forum/repair/hp-34401a-dmm-with-leaking-segments/)
https://github.com/openscopeproject/HP34401a-OLED-FW (https://github.com/openscopeproject/HP34401a-OLED-FW)
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its a matter of decoding / understanding all of this, and create the needed interface, mcu based, fpga based etc ....
This is indeed a shift register as kilobyte suggested. The data bits D1, D2, D3, and D4 are clocked in at 1.2 µs intervals (833 kHz) on the falling edge, with "D0" (the white trace) as the clock signal. Since each data sequence is 4 bits, it takes two clock pulses to form a complete byte. This explains the bursts of 80 clock pulses: (80clocks/2)×8 bits = 320 pixel rows in display. Each line/row contains 320 pixels, with pixels "ON" represented by zeros. For instance, the sequence 0x0C, 0xFF, 0xFF, ... translates to 11001111111111111111..., indicating that the 3rd and 4th pixels are ON. There are 97 lines per frame, where the green trace shows frame sync, useful for starting 1st line reading, and the blue trace marking the line latch, helpful for counting the lines. I’ve included few logic analyzer screenshots and the raw data file, which can be directly imported into Logic 2 software (available free at Saleae's download page). https://downloads.saleae.com/logic2/Logic-2.4.13-windows-x64.exe . feel free to decrypt my display !
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So using the Hexdump and Irfan View Raw Import results in the following image:
[attachimg=1]
Edit: Maybe an RP2040 with its programmable PIO could be able to handle such stuff, has enough RAM to keep the Data in some sort of framebuffer and update an other display. But I must admit that i never worked with the RP2040 so that is only a "feeling" seeing stuff others have done with the RP2040 and its PIO unit.
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I’m a bit concerned about fitting the LCD, the long "bar" style is rare. The closest option has high resolution; I’ve found an RGB 565/666 parallel display with 960x320 resolution. This requires a lot of IOs, using up almost all the GPIOs on a PI2040, and it would also consume a significant amount of RAM. I’m not even sure if 262kB would be enough. PI PIO is nice but I have no idea how to use it right..
The ESP32’s PSRAM is theoretically fast enough, and maybe an external shift register could handle the parallel to serial conversion to clock in the data at a reasonable speed using the native SPI on the ESP32. This would need to be faster than approximately 833kHz x 4. I’m confident the ESP32’s SPI can manage 5MHz. Again, this is just a supposition. I’m planning to get some materials in-house: PI2040, ESP32, and the display.
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So using the Hexdump and Irfan View Raw Import results in the following image:
(Attachment Link)
Edit: Maybe an RP2040 with its programmable PIO could be able to handle such stuff, has enough RAM to keep the Data in some sort of framebuffer and update an other display. But I must admit that i never worked with the RP2040 so that is only a "feeling" seeing stuff others have done with the RP2040 and its PIO unit.
impressive !