| Electronics > Repair |
| LCD or OLED retrofit for PM6690 / FCA3000 / CNT-90 frequency counter |
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| Smile2016:
--- Quote from: coromonadalix on November 08, 2024, 05:18:16 pm --- can you measure diagonally and or width lenght ... thks --- End quote --- 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. |
| Smile2016:
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.. |
| Smile2016:
--- Quote from: kilobyte on November 06, 2024, 09:19:57 pm ---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. --- End quote --- 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.. |
| coromonadalix:
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/repair/hp-34401a-dmm-with-leaking-segments/ https://github.com/openscopeproject/HP34401a-OLED-FW |
| Smile2016:
--- Quote from: coromonadalix on November 09, 2024, 11:56:53 am ---its a matter of decoding / understanding all of this, and create the needed interface, mcu based, fpga based etc .... --- End quote --- 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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