Recent Posts

1

Microcontrollers / Re: Memory model for Microcontrollers

« Last post by nctnico on Today at 11:05:05 am »

How would one go about telling the compiler to put this lookup table in its own section in flash, and not in the RAM?

Generally, using
    __attribute__((section ("sectionname")))
    const type varname[] = {
        values...,
    };

Any decent compile/link ecosystem should by default put const data in flash unless explicitly told to do otherwise - as mentioned there are sometimes reasons to do otherwise, like harvard architectures that may have a speed penalty, or where flash and RAM have different access speeds, but these should be something that has to be explicitly requested.

I agree. Using sections is a complicated way versus simply using const if the goal is to have data in flash.

Often there are a whole bunch of sections in the linker descriptor file which doesn't make making changes easy. And the linker descriptor file will vary per target / microcontroller type so using sections doesn't make code very portable either (besides needing to document the non-standard sections). So in general I'd advise against using sections unless there really is no alternative way.

2

General Technical Chat / Re: What ICs are used in this rocket?

« Last post by 5U4GB on Today at 11:04:20 am »

They do - plenty of PSU ICs available on LCSC, they're just harder to find due to LCSC's poor parametric search and the datasheets being in Chinese.

You can also see this in action sometimes when disassembling different generations of Chinese-made electronics, older versions will have recognisable parts in them, then they'll start sprouting vaguely-similar Chinese equivalents with minimal info available, and finally completely alien parts with no info available.  It's a bit like the SF movie/story Screamers / Second Variety which starts out with known devices and then over time they become more and more alien.

3

Beginners / Re: How to interface with cheap MC'ers

« Last post by Nominal Animal on Today at 11:03:59 am »

I'd use Free PDK.

4

Test Equipment / Re: What is good spectrum analyser Agilent ESA E4403B or Agilent CSA N1996A ?

« Last post by Cooperhop on Today at 11:03:56 am »

Does the Agilent ESA series spectrum analyzers have faster refresh rate ?

How important is to have faster refresh rate when it comes to spectrum analyzers ?

5

Beginners / [Raspberry pi] 3.5 inch display - rotation does not work

« Last post by bodzio_stawski on Today at 11:03:29 am »

Hello!

This week I started learning about Raspberry PI 4B and a 3.5 inch MHS display - the same model as described here:

http://www.lcdwiki.com/MHS-3.5inch_RPi_Display

So the drivers come from github from goodtft, updated basically on a regular basis:

https://github.com/goodtft/LCD-show

First of all, I installed Raspberry PI OS. Unfortunately, I realized I didn't have a MicroHDMI cable, so I had to settle for VNC to start with. Thanks to this, I managed to connect remotely to Raspberry before I could even install the LCD driver.

Unfortunately, due to my ignorance, I started installing the driver for the Waveshare 3.5 inch display instead of MHS, then I simply formatted the SD card with Raspberry OS and installed everything again. Then I started working on the LCD driver for the MHS display according to the guide from the link a few lines above. And it installed.

Now I control it via VNC and everything can be seen on the LCD, or control it on the LCD itself (touch screen function works). However, it turns out that the screen rotation option is somehow disabled permanently and changing the parameters related to it does not affect it.




According to some information from the Internet, it should be possible to set it this way:


a) Using the following commands - nothing changed for me:

Code: [Select]

cd LCD-show/
sudo ./rotate.sh 90b) By reinstalling and setting the rotation at the very beginning - nothing changed

Code: [Select]

sudo rm -rf LCD-show
git clone [url]https://github.com/goodtft/LCD-show.git[/url]
chmod -R 755 LCD-show
cd LCD-show/
sudo ./MHS35-show
c) By getting into the config.txt file and trying to change this value "90"; this didn't change anything, so I also tried changing the name mhs to tft35a, and then mhs35 to piscreen,drm (To make sure that the manufacturer did not deceive me with the print on the silkscreen):

Code: [Select]

dtoverlay=mhs35:rotate=90
 

Code: [Select]

# For more options and information see
# http://rpf.io/configtxt
# Some settings may impact device functionality. See lin>

# uncomment if you get no picture on HDMI for a default >
#hdmi_safe=1

uncomment the following to adjust overscan. Use positi>
# goes off screen, and negative if there is too much bor>
#overscan_left=16
#overscan_right=16
#overscan_top=16
#overscan_bottom=16

uncomment to force a console size. By default it will >
# overscan.
#framebuffer_width=1280
#framebuffer_height=720

uncomment if hdmi display is not detected and composit>
#hdmi_force_hotplug=1

# uncomment to force a specific HDMI mode (this will for>
#hdmi_group=1
#hdmi_mode=1

 uncomment to force a HDMI mode rather than DVI. This c>
# DMT (computer monitor) modes
#hdmi_drive=2

# uncomment to increase signal to HDMI, if you have inte>
# no display
#config_hdmi_boost=4

# uncomment for composite PAL
#sdtv_mode=2

uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800

# Uncomment some or all of these to enable the optional >
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

Uncomment this to enable infrared communication.
#dtoverlay=gpio-ir,gpio_pin=17
#dtoverlay=gpio-ir-tx,gpio_pin=18

# Additional overlays and parameters are documented /boo>

Enable audio (loads snd_bcm2835)
dtparam=audio=on

# Automatically load overlays for detected cameras
camera_auto_detect=1

Automatically load overlays for detected DSI displ>
display_auto_detect=1

# Enable DRM VC4 V3D driver
#dtoverlay=vc4-kms-v3d
max_framebuffers=2

Run in 64-bit mode
arm_64bit=1

# Disable compensation for displays with overscan
disable_overscan=1

[cm4]
# Enable host mode on the 2711 built-in XHCI USB con>
# This line should be removed if the legacy DWC2 con>
# (e.g. for USB device mode) or if USB support is no>
otg_mode=1

[all]

[pi4]
# Run as fast as firmware / board allows
arm_boost=1

[all]
hdmi_force_hotplug=1
dtparam=i2c_arm=on
dtparam=spi=on
enable_uart=1
dtoverlay=mhs35:rotate=90
hdmi_group=2
hdmi_mode=1
hdmi_mode=87
hdmi_cvt 480 320 60 6 0 0 0
hdmi_drive=2For now, the screen still doesn't rotate. Thanks to this, I always have the screen with the power cable facing down, which makes it difficult to place it normally. I checked this error by installing Raspberry Pi OS 64-bit and then 32-bit (both via Raspberry Pi Imager v1.8.5, released 2024-03-15)

Is it possible that something has been messed with in the RPI settings since these reinstallations, that the screen rotation option is blocked, or am I just doing something else very wrong? I will be grateful for your help.

Regards

Bogdan

6

Test Equipment / Re: DHO924S vs MSO5074 vs SDS804XHD+AWG

« Last post by Muttley Snickers on Today at 11:01:20 am »

Welcome to the forum.   

Posting the same content across multiple boards really is frowned upon here and people do get banned for it. You cannot delete a thread but you are able to move it into a different board using the "Move Topic" button at the bottom left of your thread then select a new location.

7

Buy/Sell/Wanted / Re: Canceled Because Thread All Shit Up by "tggzzz"

« Last post by tggzzz on Today at 10:59:30 am »

I found his insight here amusing though. Called for not so much.

I have this mental image of tggzzz sitting in his week-old undies and moth-eaten robe, in the corner of his tiny, gloomy, cold-water flat, in a poverty-stricken slum section of Birmingham, pecking away at his twenty-year-old Pentium computer while desperately searching forums and threads for topics wherein he can spew out his unwelcome drivel and negativity and display his legendary (in his own mind) philosophical and technical superiority as compared to the woefully ignorant and uninformed commoners who participate in these threads looking for useful suggestions from fellow members, as he, the self-ordained master of thread imposition, reflects within himself how utterly failed as a human being he is, as he seeks out these thread-killing opportunities so as to feel somewhat compensated for his lifelong worthlessness and complete failure to achieve anything noteworthy or meaningful.

I'd forgotten that; life's too short to keep grudges. Much easier (and better) to concentrate only on what people say.

Not a bad insult, I'll agree. Not relevant, nor accurate, but that's a different point!

What he missed is:

Keeping him self warm with the space heaters the old vacuum tube based analog scopes are. 

How dare you! 

I have a maximum of one tube per scope, and some of those are were DSOs. In general I refuse to have anything I can't easily lift with one arm. (Exception: affordable portable 21GHz spectrum analysers aren't easy to lift)

The only tubes I have are inside a couple of amusing instruments, are ceramic, and smaller than my thumbtip. I will admit to owning some dekatrons and neons and panaplex displays. No heaters in those, though!

As to the quote

It looks like a lot of American people seem to forget where their roots lie. 

So do people this side of the pond "People are people, the whole world over".

8

Test Equipment / Re: SCPI - get instantaneous channel reading DS1054Z

« Last post by Njk on Today at 10:55:46 am »

Test Controller seems suitable. But DS1000Z has its peculiarities and there must be a reason it's not supported by this software. Ask HKJ

9

General Technical Chat / Re: What ICs are used in this rocket?

« Last post by mikeselectricstuff on Today at 10:52:54 am »

Now you're asking us again about stuff the commies have? All your "schematics" use Linear Tech parts - the most expensive in the business.

Thanks, so do the Chinese have these kind of speciality  power supply control chips like the Analog.com ones, and the ti.com ones etc etc?
..but they just dont sell them to the rest of the world?
..or..So you are saying they only make the "big stuff"?, like the motors etc?

They do - plenty of PSU ICs available on LCSC, they're just harder to find due to LCSC's poor parametric search and the datasheets being in Chinese.

10

Projects, Designs, and Technical Stuff / Re: Unable to communicate with I2C fuel gauge

« Last post by selcuk on Today at 10:50:41 am »

I haven't used that IC before but it will be helpful if you share the DTS file you use for defining the LTC2959. Someone experienced can see if there is a wrong parameter.