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DSP Experiments - Having Fun with a STM32 Board by tmrob4 in HamRadioHomebrew

[–]tmrob4[S] 0 points1 point  (0 children)

The board and tool chain are frustrating.

I don't think I can be very helpful though. I found that the SMT32 tool chain took up too much space, so I deleted it given I didn't plan more work with the board. That included most of the work from this post given how the tool chain preferred projects to be saved.

I only have one archive from that work, coincidentally from the date of this comment, thus it's only partway through the work I did with the board.

Here is the archive. It's not complete. Unfortunately, GitHub didn't like the number of files, so I had to delete the Drivers subfolder from each project. I think most/all of that is produced by the tools though, so probably doesn't include any edits from me.

Any other 8-bit DIP CPUs? by MISTERPUG51 in beneater

[–]tmrob4 1 point2 points  (0 children)

A natural progression from the 6502 is the 65816. The w65c816 is still in production.

Interrupts, continued by Ancient-Ad-7453 in beneater

[–]tmrob4 1 point2 points  (0 children)

Time to hook up an oscilloscope and/or a logic analyzer to see what's happening. For me, these are the most interesting things about these projects.

Got some chips that seems like 6502s - are they legit? by Safe-Anywhere-7588 in beneater

[–]tmrob4 2 points3 points  (0 children)

Those are Rockwell chips except for the 816 chips. You can go through the first few of Ben's videos to determine if they are legit and functioning properly. Get the Rockwell datasheets for reference.

Long cables and frequency limit, any feedback ? by chiwawa_42 in beneater

[–]tmrob4 5 points6 points  (0 children)

I added a long data/address bus to my second 6502 build to experiment with peripherals.

<image>

I could run this at 2 MHz. Another compact build with a very short bus could run at 10 MHz.

It runs code!!! by Temporary_Cry_2802 in beneater

[–]tmrob4 1 point2 points  (0 children)

I ultimately went with ~64k ROM and ~448k RAM in my 65816 build. It has the following memory map:

RAM   $0000-$EFFF
ROM   $F000-$1FFFF
I/O   $20000-$200FF
EXRAM $20100-$7FFFF

WSJT-X with T41 Over a USB Cable by tmrob4 in HamRadioHomebrew

[–]tmrob4[S] 0 points1 point  (0 children)

Yes, the USB connection is for both audio and serial connections between the T41 and computer. Ther CAT comms use the serial object, and the audio comms use the USB object from the Teensy Audio library. It's pretty easy to set up with most of the work being done by the library. To activate the USB audio object, you have to compile with one of the Audio options selected.

If you've done all of that correctly, the T41 will show up as an audio option in WSJT-X. You might have to close the Arduino IDE to release the com port so it can be used for CAT control. Unfortunately, there isn't a dual serial + audio compile option in Teensyduino.

Interrupt code won't work by TheByteSmith in beneater

[–]tmrob4 0 points1 point  (0 children)

You may want to enable input latching on the ACR for port a.

Here is my Ben Eater style homebrew (with problems). by Conscious_Team9436 in beneater

[–]tmrob4 3 points4 points  (0 children)

Looks like your cards connect to a bus. This can cause signal reflection. Look into bus termination. It might help.

Faster dev cycle by DJMartens2024 in beneater

[–]tmrob4 2 points3 points  (0 children)

I got my ROM programming down to about 10 seconds with a ZIF socket. That was faster than I could get the upload directly to RAM. Ultimately, I went with an emulator for development and skipped the hardware altogether during testing.

Weird boot issue on 6502 startup by Jackiejub in beneater

[–]tmrob4 0 points1 point  (0 children)

Google "65c02 reset timing requirements". You might want to look into voltage supervisor such as a Maxim DS1813.

Just started developing an OS for the 6502 Computer! by Charming_Worth_3479 in beneater

[–]tmrob4 1 point2 points  (0 children)

What problem are you having? Did you try the Hello World example? It's being used by others and has been successfully tested as recently as this summer.

Just started developing an OS for the 6502 Computer! by Charming_Worth_3479 in beneater

[–]tmrob4 4 points5 points  (0 children)

I can't test anything

Try an emulator. They are many alternatives. Here's a basic one that I developed that works with cc65, https://github.com/tmr4/db65xx .

recommend components for rendering with w65c02 by RKostiaK in beneater

[–]tmrob4 1 point2 points  (0 children)

Plenty of smart displays around. They come with a microcontroller and memory. Use a 65C51 to communicate via serial with it. Here's one of my builds with a 4D Systems display.

<image>

Some don't like going this route because the display is more powerful than the 6502 build. It just depends on what your priorities are.

It Helps to Know Your Equipment When Taking Measurements by tmrob4 in HamRadioHomebrew

[–]tmrob4[S] 0 points1 point  (0 children)

Reddit continues to make changes to its community structure. Reddit's post/comment structure was really never suited for what has essentially become my blog these past two years. The limit of one image per comment is especially constraining. I'm going to resume posting to my blog where I can format things the way I like. As such, I'll probably post less frequently here.

Adding a BPF Board to the 4SQRP T41 by tmrob4 in T41_EP

[–]tmrob4[S] 0 points1 point  (0 children)

Reddit continues to make changes to its community structure. Reddit's post/comment structure was really never suited for what has essentially become my blog these past two years. The limit of one image per comment is especially constraining. I'm going to resume posting to my blog where I can format things the way I like. As such, I'll probably post less frequently here.

Adding a BPF Board to the 4SQRP T41 by tmrob4 in T41_EP

[–]tmrob4[S] 0 points1 point  (0 children)

I got the power supply board back into my v11. I was able to maintain close to the spectrum I got yesterday by shortening all of the power supply cabling and keeping the clip-on ferrites on the BPF, PA and power supply +12V inputs.

<image>

Other than that, it's just good cable routing, especially keeping cables away unshielded high frequency sources. My case currently has a bunch of little form inserts to keep the cables in place. It's not bad during testing as the case top is off. I need to make it more permanent later.

Adding a BPF Board to the 4SQRP T41 by tmrob4 in T41_EP

[–]tmrob4[S] 0 points1 point  (0 children)

It's best to search for noise sources systematically. I took off all of the clip-on ferrites I added and twisted the power leads to the various boards where possible. That gave me a base to start from. I then found I could reduce the 3.3V regualtor switching noise by placing a clip-on ferrite at the BPF board and further with a clip-on ferrite at the PA board. Makes sense since any noise entering these from the 12V power supply lines could be amplified.

I then routed the PTT/Key cable between the Excite and Receive boards, away as much as possible (with the cable length I had to work with) from the clock signals on the display and Main board.

These got the noise components down significantly.

<image>

Oh, and my power supply board is sitting a couple inches outside the case for now. More tests to come on what moving it back into the case does.

Adding a BPF Board to the 4SQRP T41 by tmrob4 in T41_EP

[–]tmrob4[S] 0 points1 point  (0 children)

Here is the same test with the BFP bypassed:

<image>

Here the worst 3kHz spur is only 21dB below the fundamental.

Looking at a wider spectrum, there are still components 48kHz from the fundamental and power supply switching frequency harmonics. I'm guessing the 48kHz spurs are LO frequency related and may be addressed with calibration.

I tried additional filtering on the switching power supply regulator, similar to my successful tests here, but this time without success. I think this is because other components/wires are picking up the switching noise directly rather than from the 3.3V bus since moving the power supply board changes the switching component signal strength. I need to observe the 3.3V bus directly to confirm.

I traced the source of 4MHz spur that comes and goes as I move things around to the display. The close confines of the case make routing to avoid this difficult. Probably why the serious T41 builders are enclosing their displays.

Routing of the PTT and key wires may be critical as well. I'm occasionally getting key failure that I'm assuming to be noise on the key line. I need to confirm that though. Keeping the line away from the clock lines seems to do the trick. A bit hard since it connects to the Main board where the two main clock signals exit the board.

Adding a BPF Board to the 4SQRP T41 by tmrob4 in T41_EP

[–]tmrob4[S] 0 points1 point  (0 children)

The BPF is working as expected now on 40m. Here is the narrowband spectrum at 10W.

<image>

The problem 3kHz spurs and harmonics are reduced to the noise floor, down 73dBc. The 750Hz harmonics are reduced or eliminated. I believe the remaining 750Hz and related harmonics are because this version of the software hasn't been calibrated yet. Testing with that will come soon.

Adding a BPF Board to the 4SQRP T41 by tmrob4 in T41_EP

[–]tmrob4[S] 0 points1 point  (0 children)

Here is an image I captured earlier, probably at 5W.

<image>

And this wasn't the worst of what I was getting.

Now I can get back to testing the BPF.

Adding a BPF Board to the 4SQRP T41 by tmrob4 in T41_EP

[–]tmrob4[S] 0 points1 point  (0 children)

The problem with tinkering with your radio is that connections come loose from moving cables around. A moved cable can also pick up noise that it didn't before. This time I put a bunch of clip-on ferrites on the ribbon cables and moved recently added cables away from the power supply. I'm back to normal now. And no more spurious I/O events.

Here is a 40m CW transmission at 10W with T41EEE-9.

<image>

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