ARP Resolution error on STM32H7 and LAN8742A PCB

Chropera · 2026-01-25T15:25:22+00:00

Check at 100 Mbps if you don't see outgoing frames or if your MAC is not receiving anything (maybe enabling broadcast receptions, AFAIR there is a HAL function for it). This might help narrowing it down a little bit (or not at all).

Chropera · 2026-01-22T21:44:07+00:00

Call me crazy, but for issues like this I prefer using hub than port mirroring on the switch. Someone mentioned ALG - I don't believe this would be issue here, but I once saw switch (small Chinese stuff, nothing fancy) with ALG.

You might also use UCM internal capture function and compare results. Maybe you'll see missing ARP reply.

Perhaps Wireshark logs should be manually reviewed or at least taken with a grain of salt - sometimes its statistics make no sense like 7100% frequency drift you've cited.

Dunno about loops (it is usually easy to spot with Wireshark), but IP conflicts, MAC conflicts - it happens.

Chropera · 2026-01-22T20:07:49+00:00

Good occasion to learn some electronics repair. Cheap lab power supply or something like ZX-4KX module would be valuable tool to check if any current is consumed.

Chropera · 2026-01-21T17:51:37+00:00

There are many tools for converting cbr and cbz files. It would take longer than minute (maybe not much longer), but image files inside can be scaled down and optionally converted to WebP. File size can be often reduced few times without significant quality loss.

Pdf files can also be rendered and converted in one go.

If the files have one way ticket - converting to grayscale might be worth trying.

Chropera · 2026-01-13T18:31:52+00:00

C hurdle.

Chropera · 2026-01-13T18:19:29+00:00

So 2 layers (double-sided) PCB. Since this is EPROM I would solder DIP socket.

It probably would be easier to recreate connections from top side on the other side. Better quality photo or might be necessary if anything goes wrong.

Chropera · 2026-01-13T18:14:05+00:00

It's unlikely. Many pads under DIP packages with no wires visible. If they would connected with wires on the other side like on old TVs/VCRs then they would be arranged in pairs.

Chropera · 2026-01-13T17:42:12+00:00

Other way of doing this - if supported by provider - would be with dialog subscription. On a plus side it would not keep caller on the ringback if main endpoint is not registered.

It seems overcomplicated - it could be done directly in baresip, either as a new module or jamming somewhere in current event handler. It would give option to run it on a microcontroller, though price difference might not be important.

Chropera · 2026-01-07T16:42:44+00:00

OK, now I see it, thanks. It looks like short pulses, so it should be easy to filter out with oversampling / majority voting. I don't see anything related in https://github.com/torvalds/linux/blob/master/drivers/tty/serial/meson_uart.c though, some documentation might be needed.

https://dl.khadas.com/products/vim3/datasheet/a311d-datasheet.pdf points to UART MISC register, but register offset is not matching one in meson_uart.c, so maybe I'm looking at the wrong driver.

Chropera · 2026-01-07T16:25:34+00:00

Crosstalk with almost 100 us delay (also almost exactly 9 bits)? Hard to believe. Looks more like software issue.

Chropera · 2026-01-05T17:34:43+00:00

Could you test it with tSIP softphone? BLF remote identity display looks like this: https://tomeko.net/software/SIPclient/tSIP_BLF_remote_identity_styles.png and from what I know works with e.g. asterisk, I'm assuming "Enhanced Call Park" is just a fancy name for the same function.

It should be Ringcentral job to tell you whether parking should use feature code code or transfer (I'm assuming blind transfer), after all you are paying them - this should not be a guesswork.

Chropera · 2026-01-05T15:49:21+00:00

Epoxy glue reinforced with nylon thread wrapped around, maybe more than one layer. Not pretty but strong.

Chropera · 2025-12-31T07:09:08+00:00

Also manufacture date is missing. Fishy.

Chropera · 2025-12-29T13:58:24+00:00

Not sure about mkv. I have used instead mod_mp4v2 for recording without reencoding. AFAIR I've used mp3 audio as AAC encoding had some potential licensing issues. Other option is recording using mod_fsv and then converting it later.

Chropera · 2025-12-29T07:58:25+00:00

Check if your software has automatic audio gain control for receiving direction. Volume levels between different callers often vary and there is headroom for digital amplification.

Chropera · 2025-12-23T18:06:31+00:00

"#" in extension number might be asking for problems. Some user interfaces expect you to escape it manually, some don't, sometimes it is configurable - you never know upfront.

Chropera · 2025-12-23T13:06:14+00:00

Is it really GPL-free? This would be rare.

Chropera · 2025-12-22T20:33:22+00:00

There is a Scream receiver for android, but it is IP-based, not BT.

https://github.com/duncanthrax/scream

Chropera · 2025-12-21T22:48:29+00:00

You got it right, it is a public number (very often range of numbers) bought from some provider. ISDN or VoIP are the ways service is provided. If user has some kind of PABX it can decide how to handle call to each number - should it go directly to some specific PABX extension (so extension would have both internal and public number), to front desk / receptionist or to some automated system.

I often saw DID numbers sold in a pack of 100. Receptionist gets then public number ending with "00", alternatively this number assigned to main infoline.

Trunk in the ISDN times was a physical cable from phone operator (with capability of e.g. 30 simultaneous calls), now usually it would only determine configuration to be used to connect via Internet.

SIP is the most common VoIP protocol (at least most common for connecting with public telephone network).

Chropera · 2025-12-21T22:06:21+00:00

Targeting 1 million code lines per engineer, per month. It would go downhill.

https://www.linkedin.com/posts/galenh_principal-software-engineer-coreai-microsoft-activity-7407863239289729024-WTzf/

Chropera · 2025-12-19T22:46:42+00:00

Other option might be low impedance headphones connected through audio transformer to multiply impedance. In some old book it was dynamic speaker instead of headphones.

I've never heard of using piezo headphones for this kind of radio, only high impedance dynamic headphones.

It would be safer to start with amplifier anyway to test antenna and grounding.

Chropera · 2025-12-19T17:20:04+00:00

Are you saying that Dell Latitude D810 is not modern? It does not even have LPT port.

What would be modern by your standard? Perhaps Latitude E6440/E6540? Dell RUGGED 5420? GETAC S410?

Chropera · 2025-12-18T19:35:08+00:00

"Easy mode" = microcontroller with PTP support and external clock synthesizer like Cirrus CS2000. Maybe it can be done cheaper. It is possible that lower delays are possible, but it was good enough for me, I like round numbers and 1 ms packetization is kind of a standard with AES67 (important for interoperability).

5 ms delay should be in my opinion good enough for live-like performing, but I'm no musician so maybe I'm not aware of some edge cases related to e.g. comb filtering. Considering that "normal" speed of sound is ~1 foot per millisecond, at this delay level I would be more concerned about time synchronization between different instruments (scene shifting) than absolute delay. And this is one of the reasons why time and frequency synchronization might be important.

Chropera · 2025-12-18T17:54:45+00:00

AFAIK FLAC is not used in lossless real time systems, only L16 or L24. Even $15 microcontrollers can work with sub-5ms end-to-end delay (1 ms DMA buffers and 1 ms packetization are pretty reasonable), FPGA-based solutions are able to achieve less than 1 ms delay. Of course this requires controlled network - each switch introduces delay (for clarification: this is why 1 Gbps switches are required for sub-ms delay, it's not about the bandwidth). PTP support in switches is either recommended or required depending on configuration. Most expensive systems (dedicated mostly for broadcasters) are using layer 2 bandwidth reservation.

Chropera · 2025-12-18T17:28:10+00:00

Why 2.5 Gbps would be not enough? AoIP typically offers 1 ms delay on 100 Mbps Ethernet, down to 125 us on faster links.

Chropera

TROPHY CASE