Looking for TFT hardware config guidance

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1

I purchased a few of these st7789 modules and have been unsuccessful getting them to work. I see that these modules may be configured for parallel mode or spi mode. The module uses the zjy-ips130-v2.0 24 pin version and I assumed the module to be configured for spi mode as default. I would like to ask if this is correct (see pull up resistor config in pic).

I have not found a datasheet for this item so if anyone has a datasheet to share it would be appreciated.

Thanks
Jim

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2

I feel your pain. When purchasing something new I get a data sheet and hopefully code and hardware examples if it appears they are needed. If I cannot get the data I save my money for the next item.

3

My interpretation would be that with R5 (labelled "PAR") populated and R4 (labelled "SPI) unpopulated, it's configured for parallel operation.

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4

I guess I'll swap the two resistors and see if that is correct. Without a datasheet that is about all one can do. Thanks.

5

No luck. Moving the resistor over did not resolve the issue.
Thanks anyway.

6

The data sheet is here. Interesting stuff starts about page 32, serial interface data on page 55.

The one I have only has 7 pins and is serial.

7

Is this of any help?

PIN No Symbol Description:

  1. DC: In parallel mode, it is the data and command control pin; in SPI mode, it is the SPI clock line
  2. CS: Chip select is active low.
  3. RD: Parallel reading
  4. SDC: parallel port is parallel port write, SPI communication is SPI DC pin
  5. D0: Parallel data D0
  6. SDA: SPI communication data line
  7. D2: Parallel data D2
  8. D1: Parallel data D1
  9. D4: Parallel data D4
  10. D3: Parallel data D3
  11. RES: reset low level reset
  12. D5: Parallel data D5
  13. D7: Parallel data D7
  14. D6: Parallel data D6
  15. BLK: Backlight, default can not be connected, low level turns off the backlight
  16. TE: Generally not used for synchronization
  17. VCC: power supply positive 3.3V
  18. GND: power ground
8

So.... you are saying:

  • DC: In parallel mode, it is the data and command control pin; in SPI mode, it is the SPI clock line
  • SDC: parallel port is parallel port write, SPI communication is SPI DC pin

have an opposite definition? Go figure. I'll study the datasheet for the st7789. Confusing to say the least.
Thanks

9

The mode select pins determine the function of some pins. See table 6.2 starting on page 33.

10

What I really need is a pin map of the ST7789 to the flex cable 24 pin out. The datasheet for the ZJY-IPS130-V2.0 would provide this.

11

Does this help?

FPC connector
FPC connector1025×652 301 KB

Source: https://www.aliexpress.com/item/1005004616439595.html

12

Looks like exactly what I was looking for. Thanks.
Today will get busy and see what I discover.
take care

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image
image924×408 64.7 KB

Just another exercise in frustration. There never seems to be a shortage of these types of documentation issues.

Well after 'buzzing' the board and checking against the pin out, here is the correct way to use this module in SPI mode. The board build configuration defaults to parallel mode. The SDC and DC signals are confusing and need swapping as shown. R6 is a pull down resistor which pulls down the CS line, enabling the module if the CS signal is not used.

Also needed to use spi mode 3 (tft.init(240, 240, SPI_MODE3); ) for proper operation. Hopefully, this will help someone else with their issues.

Thanks again to all for their help.
Jim

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