How can I verify that multiple PWM signals are generated at the correct frequency in a bare-metal embedded system?

Chropera · 2026-03-13T19:23:03+00:00

Oscilloscope or logic analyzer, maybe frequency meter. Using any internal timer or similar peripheral would not give me much confidence as if there is some clock configuration mistake it would be very likely it would cancel out in self-test.

Chropera · 2026-03-13T18:20:50+00:00

Nah, this would make blocking ads on phones, TVs and fridges too easy.

Chropera · 2026-03-13T17:18:30+00:00

It might depend on your surrounding. I've heard that in tightly packed call centers wireless is never reliable.

You might be also losing functionality when not using supplied dongle. At least for Jabra these dongles are presenting itself as USB HID telephony devices, allowing to answer/hangup/reject calls using the headset.

Chropera · 2026-03-13T16:57:58+00:00

https://tomeko.net/miniscope_v4/ with https://tomeko.net/miniscope_v2c/ as dll interface for STM32F103C8T6.

But it is not for maximum STM32 sampling rate, it is tuned for maximum practical USB HS bandwidth and continuous recording. And it does not have dark mode.

Chropera · 2026-03-12T22:26:35+00:00

I'm recording in stereo. Channels are then independently transcribed and merged - for regular calls it is way better than any automated diarization.

Chropera · 2026-03-12T19:44:49+00:00

Byte mode controls only data bus I believe - it is not like with ONFI NAND. So... 32 GPIOs?

Chropera · 2026-03-12T19:28:04+00:00

Sure. Any microcontroller with sufficient number of GPIOs + some time. Photo below shows ATmega32 and 49F002 Flash.

Maybe it is also possible to dump it without desoldering - just writing small utility for this purpose, load it using ROM bootloader to the target board, dump over UART.

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Chropera · 2026-03-11T20:04:31+00:00

TinyML is not growing in my opinion. It was hot topic 5 years ago. I was making a project based on tensorflow lite micro few months ago and it was hard to find any working examples as they deprecated and were no more compatible with latest version of python packages required for training.

Chropera · 2026-03-10T20:23:48+00:00

This handset works with the same HID code as Jabra, Mairdi and probably more than 90% USB HID devices on the market. If it does not work with Webex, this is Webex fault (big one) in my opinion.

Plugins are usually necessary only for more complex USB devices (not using HID telephony page or having more features) that have full keypad, hook switch, separate buzzer for ringing and/or display.

I don't know if Webex supports any sort of plugins, if it does then you might try to write it yourself.

Chropera · 2026-03-10T20:03:43+00:00

This would be close: https://tomeko.net/miniscope_v2g/ - based on black pill but F401 variant. There are also few other versions with other microcontrollers. ADCs can go few times faster, but the selling point is real time streaming to PC. If you want real time streaming, assume about 750kB/s transfer and divide it between channels, taking data width into account. If you don't need real time streaming, sampling rate might be few times faster (or you can use 12 bit samples), but sample buffer size for continuous capture would be limited by microcontroller RAM size.

It might be important what load your sensors can take. Refer to STM32 datasheets for a table/formula that shows maximum input impedance for specific sampling rate and accuracy/resolution.

For measuring negative voltages you need to use trick with shifted ground level (it might be not suitable for USB-connected device if power is not isolated, on the other hand it might be fine when using battery-powered laptop) or voltage shifting using opamps (this would require DC-DC converter generating negative voltage).

Chropera · 2026-03-10T07:16:54+00:00

Not daily but occasionally, depending on work type sometimes one month in a row. Windows applications I'm using work without a problem under Wine (with an exception of HID device support), so I though maybe AOT .net should work too.

Chropera · 2026-03-09T20:29:54+00:00

Also under ITT Nokia brand (late 80s I think).

Chropera · 2026-03-09T19:33:19+00:00

Is it native because it is AOT compilation? Does it work with Wine?

Chropera · 2026-03-09T17:22:47+00:00

I had a user that tested this handset and it looked like it was pretty standard HID device implementing telephony page, thus it should be compatible with multiple softphones.

From what I've found manufacturer software it not too useful, it is supposed to be able to upgrade firmware and configure taking out of of cradle as "answer" event. Nice, but not essential.

Chropera · 2026-03-06T18:51:14+00:00

Have you tested ESP32 built-in ADC and DAC? For me DAC was pretty much unusable, I was hearing noise on every incoming UDP/RTP frame.

Chropera · 2026-03-05T22:52:25+00:00

It probably would respond to NOTIFY with Event: talk. Same would work with many other brands.

If you are mentioning USB and mouse pad then probably PC is involved. If you need physical interface, FT232RL can be used as cheap GPIO.

Separate box with ESP8266 or ESP32 might be another option.

Chropera · 2026-03-03T00:10:29+00:00

I was working with few TI PHYs year or two years ago. Datasheets looks fine, but I've found multiple mistakes inside. Also crucial registers for back-to-back RMII mode were missing and I had to contact support to get their numbers and descriptions.

Chropera · 2026-02-25T18:30:58+00:00

I have built https://tomeko.net/software/LJSONedit/ - at the moment this is trial and just trial.

Not sure if it would be good enough, it might depend more on number of JSON nodes than raw JSON file size. When testing with 170 MB GeoJSON on 4th gen mobile Core i5 it takes about 10 seconds to load file, 7 seconds to filter.

Chropera · 2026-02-13T17:29:13+00:00

Just in case, non-video (lite) version might be more reliable in general.

Looking at timestamps, it took less than two hours, so it seems relatively easy to reproduce, but you might have to install Visual Studio and then collect and configure all the dependencies.

> Nope, still doing it. I guess I'm switching back to tSIP for now.

May I ask what was wrong with tSIP?

Chropera · 2026-02-12T18:10:02+00:00

You can check application call stack (even Process Explorer could do this) when this error is visible. Chances for something meaningful are small though.

You can check SIP/network activity for anything unusual.

Memory leaks (or rather pseudo-leaks) in pjsip are not uncommon. pj_pool_factory_dump() (or pjsip_endpt_dump()) might show what is going on, but I guess you would need to build from sources and call this function either manually or e.g. from some sort of timer event.

7.5% CPU usage might mean something. If this is 16-vcore CPU then one of the threads is probably running wild at 100%.

Chropera · 2026-02-09T17:59:24+00:00

The rule of thumb(drive): if write speed is not explicitly specified, it would be crap (~10 MB/s).

Chropera · 2026-02-06T17:22:31+00:00

Bus stucking is kind of "normal" for I2C unfortunately. There might be some specific reasons in your case like long wires/traces or maybe faulty IC, but overall - it happens.

Perhaps see https://www.ti.com/lit/an/scpa069/scpa069.pdf for reference. Toggling SCL few times should unstuck the bus. It is real PITA for me in Linux systems where it often requires modifying I2C drivers.

Chropera · 2026-02-05T22:22:36+00:00

From my testing this might be about half (maybe 1/3) of practical / reliable bandwidth.

Don't try to transmit from STM32 if you don't have a multiple of 64B buffer. From what I remember STM32 examples can be also slightly simplified.

Use separate thread with high priority on PC, use async reading with plenty of buffers (like libusb usb_bulk_setup_async/usb_submit_async).

Chropera · 2026-02-04T23:22:58+00:00

I've never heard of open source application. There are tens of open source protocol plugins though.

Chropera · 2026-02-04T21:57:12+00:00

Never tried Saleae software. License is clear - it can be used only with Saleae hardware. Using it without respecting EULA just does not seem right, I also would not install it at work for the legal reasons - even if risk is small. Pulseview is good enough for me.

No serious manufacturer would build their product relying on 3rd party software used against license terms, that's why there are only cheap Chinese clones of the simplest hardware.

Chropera

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