LCD display in gauge.. hack screen, or hack STM32??

Hi. I have been searching long and hard for an LCD or OLED inside a guage, that I could use with my nearly finished datalogger project.

I have come up with this: https://www.aliexpress.com/item/AUTOOL-X60-OBD-METER-OBD-2-HUD-Digital-Temperature-Gauge-Digital-Voltage-Speed-Meter-Display-Meter/32855225299.html

It is actually an OBD code reader / monitor thing, with display etc.

I have just ordered one to have a look at.

It has a 72MHz ARM processor in it, so I am assuming it may well be an STM32 of some kind.

Now… given that I am new to arduino, do you think I should set about trying to interface with the LCD on there… identify the driver chip, and use an SPI connection to my Arduino?

Or should I look to see if I can get STM32duino code onto the STM32 chip in there, and run it as its own device, and communicate over whatever I/O that device has? (UART, CAN) between itself and my Arduino?

What route would you go down? I want to display readings on there, but also a menu interface as well, for things like format sd card, set auto-logging on power-on, etc.

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That device is expensive enough with shipping that it's probably worth designing your own 3D printed case around your choice of display + microcontroller. Who knows what you'll find inside that device. It may be a black blob of epoxy on top of a microcontroller with no access to reflash the program.

bitbank:
That device is expensive enough with shipping that it's probably worth designing your own 3D printed case around your choice of display + microcontroller. Who knows what you'll find inside that device. It may be a black blob of epoxy on top of a microcontroller with no access to reflash the program.

It's less than 22 quid including delivery, from eBay sellers. That to me is a bargain. It's not far off what a basic needle gauge starts at.

3D printing isn't going to happen. The finish is fine for prototypes, but I might sell this finished item.

While I wait for the Gauge to come from China, I ordered the 'pod' style version of what looks to be the same device, from Amazon. I have received it today.

Far from a black blob of epoxy.

We the well known stm32 clone gd32f103.

Also what looks to be jtag pins.

Potentially very hackable!

Note that the mini-USB on the back here is actually for a vehicle OBD connection, and will be expecting +12v as well as K-Line, L-Line, CAN-Hi/CAN-Lo, etc.. It's not a Mini-USB connection!

(in most web browsers, you can right-click on the images below and choose Open Image in New tab, to view at full resolution).

I can't find any information on the TFT. It's a 2.4" 240*320.

It has an 18 pin flat-flex. I think only 17 pins are in use.

It could be an ST7735S driver, or it could be ILI9341 maybe.

I suppose I need to start trying to figure that out.

It is reasonably easy to determine your controller identity.
Common interfaces are 8080-8, 8080-16, 4-wire SPI.

Common ribbon pinouts are 37-way.
Your ribbon is 18-way withone dummy.
I would put money on 4-wire SPI

So you have to do some detective work for the interface.
Then keep your fingers crossed that a parallel 8080-x connects to contiguous Port pins.
An SPI interface is tied to hardware SPI pins.

I am not familiar with GD32. I would be much happier with regular STM32.

I would just hope you have SPI ILI9341.

Yes, if you can determine the schematic, it looks a pretty good deal. You get a smart enclosure with electronics to match automobile wiring.

On the other hand, you could add a ILI9341 display to a STM32 Nucleo board. Develop in comfort.
But spend serious money on electronics and enclosures.

David.

david_prentice:
It is reasonably easy to determine your controller identity.
Common interfaces are 8080-8, 8080-16, 4-wire SPI.

Common ribbon pinouts are 37-way.
Your ribbon is 18-way withone dummy.
I would put money on 4-wire SPI

So you have to do some detective work for the interface.
Then keep your fingers crossed that a parallel 8080-x connects to contiguous Port pins.
An SPI interface is tied to hardware SPI pins.

I am not familiar with GD32. I would be much happier with regular STM32.

I would just hope you have SPI ILI9341.

Yes, if you can determine the schematic, it looks a pretty good deal. You get a smart enclosure with electronics to match automobile wiring.

On the other hand, you could add a ILI9341 display to a STM32 Nucleo board. Develop in comfort.
But spend serious money on electronics and enclosures.

David.

Thank you David. I will try to do some experimenting tonight on both the LCD and the MCU. If I'm not to tired when I get home, I'll put the scope on some LCD pins, and maybe see if I can get OpenOCD to talk to the MCU.