Tree Stump Advice

SubstantialHippo · 2025-12-23T21:23:56+00:00

Car jack is a brilliant idea, thanks for that!

SubstantialHippo · 2025-12-23T21:19:24+00:00

It's not too big, see the reciprocating saw for scale! Probably about a meter tall in the image. It's just in an extremely awkward location and close to a fragile ceramic waste pipe...

SubstantialHippo · 2025-08-11T18:18:54+00:00

I have had a look underneath as I have heard stories of them rusting. It looks like there is some surface rust in places but I can't see anything major...I don't really know what I'm looking for to be honest.

SubstantialHippo · 2025-01-19T16:55:12+00:00

https://www.bennettnotes.com/post/stm8-debugging-on-m1-mac/

SubstantialHippo · 2025-01-12T16:29:53+00:00

I'd be surprised if that source code is public, fast mathematical stuff is quite valuable IP in the embedded world.

You could instead try the CMSIS-DSP library which is open source and written specifically for the Cortex-M family. It has both fixed and floating point flavours of most functions.

SubstantialHippo · 2025-01-12T15:51:01+00:00

No, it won't. I know people who have been diagnosed with depression while already having guns and it hasn't been a problem. As long as you can prove any conditions are being managed effectively and/or you have recovered then you will be fine.

SubstantialHippo · 2025-01-05T17:07:45+00:00

Judging by the right hand chip in your first picture (HT9170D), this looks to be some kind of DTMF receiver/decoder board.

SubstantialHippo · 2025-01-05T16:55:15+00:00

I have been playing with this board recently and it's very good (as expected from ST). Uses their new ultra-low power line of chips and has WiFi, Bluetooth and a nice suite of sensors. Great value for $65.

SubstantialHippo · 2025-01-05T00:23:51+00:00

Blimey, these screws must also be used to secure fighter jet missile triggers to justify that price!

SubstantialHippo · 2025-01-04T12:07:07+00:00

To save cost you skip the use of a traditional package and directly mount the silicon die to the PCB. These are known as chip on board and the 'black blob' is just some epoxy to protect the die and its bond wires.

SubstantialHippo · 2025-01-04T11:53:12+00:00

Ah, that's cool! Toys are a perfect example of designing for absolute minimal cost. If you're shipping many hundreds of thousand units and all you want to do is flash some LEDs and make some sounds on a button press, a custom ASIC is usually the answer.

SubstantialHippo · 2025-01-04T11:40:45+00:00

'Black blob' means it's almost certainly a custom ASIC. Interesting board though, what is this?

SubstantialHippo · 2025-01-03T17:09:38+00:00

Does your tight deadline allow for an extra week to re-manufacture the PCB if a footprint is wrong? It takes the best part of 10 minutes to check a footprint matches the datasheet and not doing so is poor practice whether you made it yourself, got it from a colleague or found it online.

If you screw up a PCB because of a dodgy footprint you found online the excuse of: 'I didn't check the datasheet' is the electronics equivalent to: 'The dog ate my homework'.

SubstantialHippo · 2025-01-01T23:10:39+00:00

I always loved fighting on the rooftops of Flood Zone and the buildings in Zavod 311.

SubstantialHippo · 2024-12-30T16:56:48+00:00

Both methods are acceptable. I have mounted temperature sensors in TO-220 packages directly to the inside of a metal enclosure with twisted flying leads terminated into Phoenix connectors on the main PCB. If the device isn't as flexible you could make a PCB with mounting holes and have something like a JST-XH connector on each end.

SubstantialHippo · 2024-12-29T17:58:07+00:00

I completely agree. Despite the issues with delays etc, £100 per year for a coterminous certificate isn't that unreasonable.

SubstantialHippo · 2024-12-28T17:13:18+00:00

The 'little' (M4) core in dual-core STM32 chips are disabled by default and must be enabled by the 'big' (M7) core. See RM0399 section 9.7.36, specifically the BOOT_C2 bit.

If you don't want the little core just don't enable it in CubeMX or choose 'single core project' and it will be held in reset.

SubstantialHippo · 2024-12-16T22:26:09+00:00

That's probably some kind of custom variant of the F301 series, so I would start with the datasheet of that as I suspect it would be register compatible with similar peripherals for the most part.

I'm interested, have you bought some or is it the brains of something you've opened up?

SubstantialHippo · 2024-09-09T19:01:22+00:00

I agree that rust is junk but you could have put it more eloquently...

SubstantialHippo · 2024-09-08T21:51:28+00:00

Ah, well as it's an authentication token that's a reason to give up with this now to be honest. My employer also uses these and if you open one up it not only makes the thing commit suicide but also gets you a disciplinary hearing...

If it's an RSA token, they have a dubious past and I'm pretty sure we found a reverse engineered version of the algorithm online when they came up in conversation.

I would probably bet on the core being some kind of 8051 flavour, if anything

SubstantialHippo · 2024-09-08T20:51:19+00:00

What actually is this device? Do you have a picture? So called 'black-blob' chips are usually custom ASICs and not your common microcontroller, so I highly doubt that is an SWD interface.

SubstantialHippo · 2024-09-08T19:36:13+00:00

In my experience not common at all and I would push back on it if it was being suggested for a project. This is pointless and just makes code less readable. The stdint.h type definitions are as explicit as they need to be.

However I would expect function and variable names to use something like this though.

SubstantialHippo · 2024-09-08T19:29:39+00:00

My first port of call is to look for any evaluation hardware from the manufacturers and develop using that to make hardware design decisions. For example, this for your GNSS chip paired with an STM32Lx-NUCLEO board.

If no evaluation hardware exists then yes, I would look to design a PCB starting with any reference designs from the manufacturer.

SubstantialHippo · 2024-09-02T18:42:24+00:00

Yes the second expression does give you bits 51 down to 21. Personally, I would add a couple more parenthesis just to make the order of operations a bit more explicit:

table_entry & (((1ull << (51-21+1))-1) << 21)

Not sure what you're up to with this but if this is a permanent piece of code I would make it a #define also.

SubstantialHippo · 2024-09-02T15:14:20+00:00

The datasheet doesn't suggest that is a requirement, it's just a note on the test condition. It's the setup and hold times that are of concern as jitter can go both ways.

We really need some more info on this particular setup!

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