Activity for Lundinâ€
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Comment | Post #293118 |
@#67945 If you can share the schematics and ideally a photo and/or PCB layout in a separate question, we can help out with troubleshooting that as well. Out of all the failures you can get during EMC testing, ESD problems are relatively easy to spot and fix. Been there done that :) (more) |
— | about 16 hours ago |
| Comment | Post #293120 |
@#67945 The problem with conditionally checking the memory and kicking the watchdog accordingly is that if the memory gets corrupted, the watchdog no longer protects against that. Which is one of the core purposes of having a watchdog in the first place.
On safety-critical systems you often use a ... (more) |
— | about 16 hours ago |
| Comment | Post #293119 |
@#67945 It doesn't matter, the purpose of the watchdog is to supervise overall well-being of the MCU. And as I noted in the answer you shouldn't get the watchdog tangled up with application-tier logic like whatever some IRQ pin is supposed to do. Instead you could have dedicated interrupts for those ... (more) |
— | about 16 hours ago |
| Edit | Post #293119 |
Post edited: |
— | about 17 hours ago |
| Comment | Post #293118 |
As we discussed before, ESD causing memory corruption or hanging the MCU etc are just symptoms. ESD testing is just as likely to regard a sudden MCU reset by a watchdog or other means as a fail criteria. If possible, I would encourage you to post a separate question here addressing the electronics de... (more) |
— | about 17 hours ago |
| Edit | Post #293119 |
Post edited: |
— | about 17 hours ago |
| Edit | Post #293119 |
Post edited: |
— | about 17 hours ago |
| Edit | Post #293119 | Initial revision | — | about 17 hours ago |
| Answer | — |
A: Is Feeding a Watchdog Timer from an ISR a Bad Practice? The problem with refreshing the watchdog from an ISR is that in case the main program hangs for whatever the reason, the ISR will keep living and could keep the watchdog alive, effectively blocking the product from recovering from an error state, making the watchdog useless. It could leave GPIO or... (more) |
— | about 17 hours ago |
| Comment | Post #292998 |
You already have 3.3V signal levels so why not connect this directly to the MCU? You just need an external pull resistor. (more) |
— | 26 days ago |
| Comment | Post #292698 |
I don't know this bus but surely stubs and termination must be a major consideration as well. A stub of just a few decimeters might have a big impact at speeds like this, causing signal reflection. (more) |
— | 3 months ago |
| Comment | Post #292688 |
Was there any printing on the batteries that gave hints about the chemistry? Maybe they weren't regular alkaline, maybe NiMH or NiCd although those are relatively safe too. Lithium chemistries are more likely to get a thermal escalation and go out with a bang in case of a short (caused by dust etc) o... (more) |
— | 3 months ago |
| Edit | Post #292375 |
Post edited: |
— | 4 months ago |
| Edit | Post #292375 |
Post edited: |
— | 4 months ago |
| Edit | Post #292375 | Initial revision | — | 4 months ago |
| Answer | — |
A: What is connector pitch and how to measure it? Pitch is defined as the center-to-center measurement between two pins/legs of the component. Connectors in particular are always categorized by manufacturers/retailers based on pitch, so it is the single-most important property to learn about when trying to identify or specify a connector. A ... (more) |
— | 4 months ago |
| Edit | Post #292374 | Initial revision | — | 4 months ago |
| Question | — |
What is connector pitch and how to measure it? When posting identification or general questions related to connectors, integrated circuits or other parts with pins/legs, engineers always speak about something called pitch. What is the meaning of the term and how can I tell what pitch my connector has? (more) |
— | 4 months ago |
| Edit | Post #292247 |
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— | 4 months ago |
| Edit | Post #292247 | Initial revision | — | 4 months ago |
| Answer | — |
A: Do hobbyist slabtop Wi-Fi modifications need to consult FCC regulations? During FCC (or any other EMC) testing, the manufacturer will use some antenna(s) and only those antennas will be the ones approved. If you modify the antenna or use one which wasn't used in the test, then the item is no longer conforming. Similarly, if a product's housing serves as signal/chassis ... (more) |
— | 4 months ago |
| Comment | Post #292089 |
When a CAN controller fails to send, it automatically tries again. It will increase an error counter and after failing a number of times go "error passive", meaning it can no longer send error frames driving the bus to the dominant state. If the error counter keeps increasing it will eventually go "b... (more) |
— | 5 months ago |
| Comment | Post #291971 |
@#52935 Yeah there are lots of mode selection pins like that on diverse MCUs. They all work slightly different however, but perhaps I should add a note about checking special pins. (more) |
— | 5 months ago |
| Edit | Post #291987 |
Post edited: |
— | 5 months ago |
| Edit | Post #291987 | Initial revision | — | 5 months ago |
| Answer | — |
A: How to operate a chip very close to its absolute maximum voltage? The term absolute maximum ratings has a well-defined meaning in datasheets, meaning stress values that the part will endure for a short period of time without breaking. And the opposite: if you exceed asbolute maximum ratings, it may break. The absolute maximum ratings of this particular part coul... (more) |
— | 5 months ago |
| Edit | Post #291971 |
Post edited: |
— | 5 months ago |
| Comment | Post #291971 |
This is a bit of a work in progress still, but I'm posting it here regardless so that I might get some feedback. Something missing? General feedback & proof-reading is most welcome! (more) |
— | 5 months ago |
| Edit | Post #291971 | Initial revision | — | 5 months ago |
| Article | — |
Troubleshooting a microcontroller that has stopped responding When working with microcontrollers, one will sooner or later face the situation where the MCU is not responding. Either it's a new PCBA you are trying to get up and running, or something that previously worked then something happened and now you are stuck. The in-circuit debugger is typically giv... (more) |
— | 5 months ago |
| Edit | Post #291745 | Initial revision | — | 6 months ago |
| Question | — |
Internal server error 500 while searching for tags Searching for a tag name using a string that doesn't exist in any tag causes internal server error 500. Reproduce this way: - Click Tags in the menu - In the search box, type something that doesn't exist as a tag, for example `bananas`. - Click the magnifying glass search icon. - Internal serv... (more) |
— | 6 months ago |
| Comment | Post #291734 |
@#56656 I've only seen it in terms of no insulation break down voltage. Though this is admittedly far from my area of expertise - I just happen to use these connectors a lot :) I think you'll need a connector expert, so poking Wurth support is probably the way to go. (more) |
— | 6 months ago |
| Comment | Post #291734 |
I think I've seen 60VAC reappearing as some "de facto" rated voltage standard for these U.FL connectors no matter brand. These are based on the Hirose U.FL series, which inconveniently doesn't seem to specify a voltage rating either (other than 200VAC breakdown). If you want to be sure for your parti... (more) |
— | 6 months ago |
| Edit | Post #291385 |
Post edited: |
— | 7 months ago |
| Comment | Post #291238 |
Ok so maybe the inductor is just meant to be (part of) a filter. Then the IC could very well be a linear regulator or just a transistor. (more) |
— | 9 months ago |
| Comment | Post #291238 |
I'm guessing the connector. And since it is a hand-held device running on batteries, voltage out to power something? Or does it use rechargeable batteries and that's voltage in? (more) |
— | 9 months ago |
| Comment | Post #291239 |
"The component to the left of the inductor in second picture looks to be a diode. It only has two terminals. The stripe at one end probably marks the cathode."
Nope, tantalum caps, the stripe marks + since they have polarity. And they like to explode :) (more) |
— | 9 months ago |
| Comment | Post #291240 |
@#52935 I found some boost converters for 3.3V by the semi-obscure brand Torex that might fit the bill, but I couldn't find any matching documentation about part markings. There's lots of linear regulators with markings 331 but that doesn't explain the inductor. Unless it is double-sided mounting an ... (more) |
— | 9 months ago |
| Edit | Post #291240 |
Post edited: |
— | 9 months ago |
| Edit | Post #291240 | Initial revision | — | 9 months ago |
| Answer | — |
A: What are these mystery components (one of wire coil, another labeled "100-10L A9")? The black one is a tantalum capacitor. There are various weird ways to mark these (because typing out `100u` instead of `100-` would be too easy...). If I'm correct in this case, I believe: - `100` stands for 100uF - `10` for 10V. - `L` is tolerance +/-10%. - From the size of it it looks like... (more) |
— | 9 months ago |
| Comment | Post #291110 |
That shouldn't be a problem for a PCB sitting in an enclosure, given that the usual anti-ESD measures were implemented.
Electronics love dry places. The more obvious issue that dry tends to go hand in hand with warm, and that's where all manner of issues can pop up. (more) |
— | 9 months ago |
| Comment | Post #291085 |
I have the transceivers failing during production and I doubt the cause is ESD. I suppose hot-plugging during testing could be a culprit, but then the type of connectors used means the ground is always there before voltages. (more) |
— | 9 months ago |
| Edit | Post #291080 |
Post edited: |
— | 9 months ago |
| Comment | Post #291082 |
I guess the TVS values were picked because we already have the same ones elsewhere on the BoM protecting 24V on/off and the like. That and taking a bit of the blow in case someone shorts the supply against data lines. We have already considered adding TVS suitable for RS-485, I noticed there are some... (more) |
— | 9 months ago |
| Comment | Post #291082 |
Oops yes this is a typo. Since the design is propriety, I cannot share it as-is, so I just quickly redrew the relevant parts in an online schematic program. (more) |
— | 9 months ago |
| Comment | Post #291080 |
@#53661 It can be hot-plugged, yeah, but I don't see it related to the failures. The PCB ground will be sitting close to the chassis ground potential - it will be grounded to chassis from where the PCB is connected, as well as at a few other places where shielded connectors are attached to the chassi... (more) |
— | 9 months ago |
| Edit | Post #291080 | Initial revision | — | 9 months ago |
| Question | — |
MAX485 transceivers breaking, Pi filter generating spikes? Problem description & speculation about causes I've having a problem with MAX485 transceivers breaking intermittently, passing our production tests but later failing. The error phenomenon is wrong signal voltage levels on the RS485 lines, as well as the transceiver failing to return the signals to... (more) |
— | 9 months ago |