STM32 in Ham Radio

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g0mgx
Posts: 8
Joined: Fri Jan 10, 2020 1:41 pm

STM32 in Ham Radio

Post by g0mgx »

I have a lot of project ideas and am now hooked on using the STM32.

My first project has completed:

https://youtu.be/AnpU52jWU4g

I'm now working on control software for an RF amplifier, will use xpt2046 touchscreen control with the ILI9341 TFT.

Software will switch low pass filters in and out of circuit as "bands" are changed, will also read from external logarithmic amplifiers to determine forward and reverse power and calculate VSWR.

I'm having fun!

Mark
G0MGX

ag123
Posts: 241
Joined: Thu Dec 19, 2019 5:30 am

Re: STM32 in Ham Radio

Post by ag123 »

+1 really cool, i've been wanting to mess with radio circuits, but is falling behind in my understanding of rf electronics

there are many articles on the web raving about ne602, ne612, sa602, sa612
https://www.nxp.com/docs/en/data-sheet/SA602A.pdf
https://www.nxp.com/docs/en/data-sheet/SA612A.pdf?
which accordingly are rf mixer chips the equivalent of the '555' of the rf world

chips like stm32f4xx and to an extent stm32f103 has a built in 'vco' that can generate (square waves, unfortunately) pretty much in the vhf rf ranges. it is that system clock pll. i've been thinking if it might be possible to feed that in as the 'LO' and kind of generate the 'IF', and the extreme of which is could we decode the consumer fm that way from the adc on chip?
the trouble of course is that i can't really understand all these

in the end i chickened out and went with pre-made fm modules
e.g.RDA5807
http://www.i-biznes.com/datasheets/RDA/RDA5807-MOD.pdf
https://www.aliexpress.com/wholesale?ca ... xt=RDA5807

even then i've not really worked my project on it. this won't be quite an 'SDR' unlike using a real sa612 chip with all the basic electronics.
i'd think stm32f4 can do all that fft and literally decode fm from an adc, or perhaps it could literally be simplier

but well, it seemed stm32 can do all that rf direct conversion receiver e.g. with sa612
https://en.wikipedia.org/wiki/Direct-co ... n_receiver

and perhaps if we can mix at 1575 mhz i'm not sure if ne612 is game for that, we may be even able to decode gps signals directly

rogerclark
Posts: 3
Joined: Fri Dec 20, 2019 2:08 am

Re: STM32 in Ham Radio

Post by rogerclark »

Most MMDVM Hotspots use STM32F103's in them. https://github.com/juribeparada/MMDVM_HS

The MCHF . HF SDR transceiver uses the STM32F4 https://github.com/df8oe/UHSDR

Most of the TYT hand held VHF/UHF transceivers, like the TYT MD-380 use the STM32F4. There isn't fully open source firmware for this, but there there is the MD-380 tools which is an open source software patching system which adds a load of additional functionality to the MD-380 https://github.com/travisgoodspeed/md380tools

In the longer term, I'm hoping to port the OpenGD77 project (which runs on GD77 / TYT MD-760 radio) to the TYT MD-380 etc, but the MD-760 uses the NXP MK22 MCU, which is a cortex M4 processor, but unfortunately not a STM processor :-(

I use the STM32F103 all the time in my Ham Radio projects. I designed a pseudo VFO add-on for a Codan HF transceiver, which had a rotary encoder as it input and fooled the Codan into thinking that the operator was pressing the UP and DOWN buttons really quickly.
Also by messing around with the main PLL and one of the timer divider, I managed to produce the BFO frequency required by lower sideband, as most Codans don't come with both the upper and lower sideband BFO crystals.
The frequency of the BFO was off by about 30Hz, so I just pulled the master crystal on the BluePill a little with a capacitor.

I've also just built a mini VFO for a Pixie QRP single board transceiver, which uses the STM32 as the controller and uses a Si5351 as the actual RF generator. This includes a mini OLED display and a rotary encoder etc.

A while ago, I attempted to convert a UV-82 VHF/VHF handheld into a mini repeater, and I had to remove the original, unknown MCU, and connect a BluePill to control the transceiver chip (AT-1846S) etc.


Someone at my local radio club, programmed a BluePill to generate Morse code for tuition purposes, with various modes e.f. 5 figure groups, at various speeds

And I'm just in the process of trying to get an old Philips UHF 815 repeater working again, and I'll be using a BluePill as the main control board, and will be interfacing it to a Si5351 as the RF generator for both the Tx and Rx units to replace the crystals.

g0mgx
Posts: 8
Joined: Fri Jan 10, 2020 1:41 pm

Re: STM32 in Ham Radio

Post by g0mgx »

I've got the initial part of my next project up and running.

It uses the STM32 blue bill board and is a controller for a RF linear amplifier.

I have implemented a touch screen to select the frequency band of operation which in turn will switch inline the appropriate low pass filters. I have also designed some logarithmic amplifiers to take a forward and reflected RF sample, convert it into dBm and then calculate the VSWR.

The TFT display is used as a touch keypad for band selection and also to display the power and SWR readings.

My code may not be the best, but it seems to work very well.

https://youtu.be/SRhXYJKR1YQ

Mark
G0MGX

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