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Hantek DSO2xxx schematics

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I decided to look into the Hantek DSO2xxx series because I like the hardware as a basis to play with.

To get an understanding of it all reverse engineering of the schematics seems the logical first step, so that is what I started with. First up is the "User Interface Board" as it is the simplest to tackle. In the other threads about the Hantek a touch panel connector was mentioned and there is indeed room for it on the board. I soldered a connector onto it and placed a touch panel in front of the display. The rubber push cushions can be turned to lower them. They have two slots in them to slide over the metal holder.

Will post some pictures of that later.

An observation of the schematics shows how they handle the buttons and the encoders. They scan them in a matrix. This might explain why the response sucks when turning an encoder.

For the user interface part I made three sheets. The first shows the connectors and the LCD power setup, the second shows the buttons and the encoders and the third shows the LED's.

I don't understand what they are doing with the pots.  They are pots, right?  So what is the point of the diodes?  Are they measuring the voltage on the wiper arm?  It makes no sense to me.  Can you explain?

They are not pots but rotary encoders, so just two switches that are closed and opened one after the other. That is why the diodes are there. It works as a key scanning matrix. A problem with this design is that the buttons don't have the diodes so pressing two at the same time could result in not detecting one of them. (When they are on the same scan data line)

The HC4051 ic's work for both analog and digital signals. U3 is used to pull the scan lines low in following order and U2 is used to connect the scan data lines to the scanner. The HC393 is setup as a six bit counter and controls the scanning.

Here are some pictures of the touch panel fitted into the housing.

The rubber stoppers need to be swapped. On the picture below you can see the top one in its original orientation and the bottom one in the swapped orientation.

Interesting, but really, don't waste too much time with it, Hantek uses customized kernel, there're no sources, so adding new features will be almost impossible unless the functionality and its dependencies can be build as module.
We've been trying to implement networking through USB (RNDIS/ECM), the usb gadget could be compiled and loaded, but the kernel was built without networking support, and this feature cannot be added as module.

AFAIK, the scope already includes and loads the module tp-adc.ko, which probably includes the touch functionality, but knowing hantek, it very likely doesn't...
The Goodix GT911 driver is disabled in the devicetree (Check it here)

--- Code: --- touchscreen@14 {
compatible = "goodix,gt911";
reg = < 0x14 >;
interrupt-parent = < 0x0c >;
interrupts = < 0x04 0x0a 0x02 >;
pinctrl-names = "default";
irq-gpios = < 0x0c 0x04 0x0a 0x00 >;
reset-gpios = < 0x0c 0x04 0x09 0x00 >;
status = "disabled";

--- End code ---


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