Controlling Special Chinese Module MAX2870 TFT Unit DDS Generator

[jemp]

HEllo All
I've obtained a small TFT Cotrolled MAX2870 from AliXpress ( see picture ) but the seller did not provide any instructions or PC software.
Does anybody has this PC controlled software ?
Does anybody know how to calibrate this module , since the main clock is about 575 Hz off and so any frequency generated has a substantial difference !!
On the back side is a jumper with calibration marked on it..
Any Manual or others ?

Tnx for any HELP, ON7MA

[EggertEnjoyer123]

You'd probably have to desolder the crystal oscillator on the board, and attach your own clock signal to "calibrate" it.

All the chip does is generate multiples of the input clock frequency, and it shouldn't need any calibration since the output frequency is locked to the input frequency.

[shabaz]

I'm not sure it's worth it. It's a very basic freq synth with steps of 10 kHz and 20 kHz depending on the desired frequency. It is not a DDS, despite some adverts mentioning that.

I was not able to get online software to function with it. It's possible to disassemble the firmware if there was a real desire to investigate computer control. The firmware binary content is easy to read out using any SWD tool. I placed the MAX2870 board firmware binary file here if anyone is interested. But, personally I think it's not of value, since one may as well make a custom freq synth board with that chip, with their desired microcontroller of choice (or use the microcontroller already on the board, but will probably be easier to just start from scratch with a custom PCB), and using (say) SCPI or some other normal protocol.

[Kees Hofwegen]

Hi,

I have a small max2870 board (not this one) that I can control through an micro controller.
In my case an arduino nano.
Using both Integer-N and Fractional-N modes I can control the frequency quite accurately ( < 10Khz).
having said that, this board probably uses Integer-N only since that is quite simple to calculate.

Control of tha MAX on that board is done with 5 registers so an analyser on the LE, DATA, Clk lines will show
what is sent to the MAX.

The rest of the code is only control for the menu's, switches and LCD.

As said by others, better to start from scratch or live with the 10Khz resolution.


Greetings Kees