Recent Posts

1

Embedded Computing / Re: Is it possible to read AHCI registers using setpci on Linux?

« Last post by RoGeorge on Today at 10:13:42 am »

I don't know to answer the question, but the Linux kernel should have a Device Tree (DT).  The DT is telling the kernel (at boot), what driver to load for each device, and any specific parameters the driver might need.  Later, that DT is mapped into a directory tree (in Linux, everything is a file), here mapped at /proc/.

For example, if I search for PCI in /proc/ of my desktop PC, there is a /proc/bus/pci/ directory, and a /proc/bus/pci/devices file.  Inside that file there is a line contaning the text ahci, and some addresses/registers.

See if you can make use of any of that info, in order to find the address you are interested in, though never tried that myself.

No idea if this could help changing the settings you are after, if it applies to your OS flavor, or if it brings anything extra other than setpci can already do/show (I don't know much about setpci).  But if it does, then it should be possible to decompile the (binary) device tree that is in use, edit the decompiled DT to add your changes in the DT sources, then recompile the DT (the decompiler/compiler is called dtc), so to make your changes persistent after a reboot.

2

Manufacturing & Assembly / Re: Advice on adding missing parts to an assembled board

« Last post by Aspartame on Today at 10:08:57 am »

I had the same issue with JLCPCB when they had stopped assembling esp32-wroom-32e module with the economy pcba service. I mounted the wroom module using a hot plate. I applied solder to the pads using a soldering iron in advance.

3

Microcontrollers / Re: Divide clock by 3 on a ATF16V8B

« Last post by xvr on Today at 10:05:56 am »

No, it's impossible.
VHDL code use triggers with positive and negative clock edges. ATF16V8B have only positive clocked triggers.
You can create simple divider by 3 on it, but you've got not symmetrical output (with duty cycle 1//3 or 2/3 - on your choice)
And for ATF you need a special programmer (hardware), do you need any?

4

Microcontrollers / Re: How to create custom bootloader in esp8266

« Last post by xvr on Today at 09:58:59 am »

> I was wondering if there would be any problems booting the program if the power goes out while updating the ESP8266 firmware?

No program - no problem  It just will not start, only builtin bootloader will survive 

5

Repair / Re: Rohde Schwarz CMU200

« Last post by ON4GN on Today at 09:56:45 am »

More photos 

6

Power/Renewable Energy/EV's / Wrong crosssection of cables

« Last post by eTobey on Today at 09:53:03 am »

I have ordered cables from 6 different places (Germany). 5 of them had sent me cables that had about 20% less crosssection than advertised. I measured via visual and electrical methods, so there is no doubt about my measurements. One one ocassion, the outer diameter had me feel that it was to little, and sure enough it was...

Have you ever checked on the cross section?

7

Programming / Re: Angle wrapping in code, "easy" problem, need to double check

« Last post by electr_peter on Today at 09:51:21 am »

P.S. any tips on angle-wrap-respecting code to determine if a supplied angle is inbetween (on the short side) another two supplied angles? Imagine "spinning a bottle" and then checking if the resulting angle is within a certain sector, the sectors not all being equally sized or spaced, so it needs to be a genuine check of "is it between these sector limit angles".

This problem is trickier than simple comparison due to wrapping issue, but still easily solvable by splitting circle in two regions.
Lets say full circle has possible angles from \$0..360\$ (360 being same as 0).
Input is angle \$X\$ and sector from angle \$A\$ to angle \$B\$ (\$A>B\$ or \$A<B\$, i.e. \$10..350\$ (340 degree sector) is different from \$350..10\$ (20 degree sector))
Split circle in to two regions - \$0..180\$ and \$180..360\$. Based on \$X\$, select \$0..180\$ or \$180..360\$ region. Recalculate \$A..B\$ sector coverage in this region, to get \$A'..B'\$ sector with condition \$A'<B'\$. Then comparison \$A'<X<B'\$ gives the answer.

8

Repair / Re: Rohde Schwarz CMU200

« Last post by ON4GN on Today at 09:50:11 am »

Hello Harry_22.
Here are the photos from the CMU-B68.

9

General Technical Chat / Re: new propellantless drive company

« Last post by EPAIII on Today at 09:49:39 am »

I didn't see anything in that article that even gave the smallest hint of HOW it is supposed to work.

Like the EM drive,

https://thedebrief.org/nasa-veterans-propellantless-propulsion-drive-that-physics-says-shouldnt-work-just-produced-enough-thrust-to-defeat-earths-gravity/

this one uses a capacitor. Instead of piezo (not that a piezo is not a capacitor) , but it sounds similar. That is that there is some unequal force in a polarizing material which leads to thrust. Not a (weak) photon drive.

10

Projects, Designs, and Technical Stuff / Re: Practically smallest SMD size for assembly run of 1 to 100 pieces by PCBWay etc

« Last post by xvr on Today at 09:48:09 am »

Why not ask PCBWay directly? I guess they know what they do much better than EEVblog community.