Go to advanced search

by lb
Fri Mar 05, 2021 12:24 pm
Forum: General discussion
Topic: NEW! zoom camera for Raspberry Pi
Replies: 29
Views: 1493

Re: NEW! zoomcamera for Raspberry Pi

How can you control the zoom via software if it doesn't require any additional software additions?
by lb
Sat Jan 30, 2021 10:04 am
Forum: General
Topic: Could the Pi Pico be used as the brains for a 3D Printer?
Replies: 38
Views: 3220

Re: Could the Pi Pico be used as the brains for a 3D Printer?

The problem with ADC on RP2040 isn't so much the number of bits, it's the effective accuracy and the lack of an accurate voltage reference. You need a very accurate LDO for good measurements, or you need to connect an external bandgap reference (which needs one of the channels, and there are only fo...
by lb
Wed Jan 27, 2021 8:38 pm
Forum: General
Topic: Could the Pi Pico be used as the brains for a 3D Printer?
Replies: 38
Views: 3220

Re: Could the Pi Pico be used as the brains for a 3D Printer?

It should be REALLY simple to port the Klipper firmware to the Pico/RP2040. It's quite minimal and pretty generic. That way you could make a 3D printer with 100% Raspberry Pi ecosystem silicon. The actual "bottleneck" of RP2040 in practice seems to be the number of ADC channels and ADC acc...
by lb
Mon Jan 25, 2021 2:59 pm
Forum: General
Topic: XIP a near-useless feature?
Replies: 11
Views: 1208

Re: XIP a near-useless feature?

Execute-in-Place is an important feature and a welcome advantage of RP2040 compared to, say, ESP8266. ESP8266 has very same architecture regarding this(?). It also uses XIP and SPI flash memory. You're right, not sure why I remembered incorrectly. I think it's common to load many functions to RAM o...
by lb
Mon Jan 25, 2021 11:11 am
Forum: General
Topic: FAQ
Replies: 14
Views: 7111

Re: FAQ

aallan wrote:
Mon Jan 25, 2021 10:38 am
There is an example in the pico-playground repo, https://github.com/raspberrypi/pico-pla ... ello_sleep
Yes, but that uses the SLEEP mode, which uses ~390 uA according to datasheet. That's not low power at all.
by lb
Mon Jan 25, 2021 8:52 am
Forum: General
Topic: FAQ
Replies: 14
Views: 7111

Re: FAQ

Is there really no usable low-power option for timed wakeup? The DORMANT state stops all clocks, so without an external low-speed oscillator for the RTC (which will consume additional power) it doesn't look like there's any way to implement a timed wakeup. Nonetheless, the DORMANT state still has a ...
by lb
Mon Jan 25, 2021 8:31 am
Forum: General
Topic: XIP a near-useless feature?
Replies: 11
Views: 1208

Re: XIP a near-useless feature?

Keeping code in RAM is rather unusual on most microcontrollers. In fact, many microcontrollers use Harvard architecture (e.g. AVR, MCS-51) and can't do that at all. On ARM MCUs it's pretty unusual, too. You sometimes keep "hot code" in RAM to improve performance or reduce power consumption...
by lb
Thu Jan 14, 2021 1:05 pm
Forum: Advanced users
Topic: [RPi0] set CPU frequency under 100 MHz ?
Replies: 35
Views: 1590

Re: [RPi0] set CPU frequency under 100 MHz ?

Hm, does it actually significantly affect power consumption? I can imagine other parts of the SoC and the RAM dwarf the CPU core's power consumption if you go < 500 MHz.
by lb
Wed Dec 16, 2020 1:43 pm
Forum: General discussion
Topic: RPi 3 Driving an N-Channel MOSFET
Replies: 15
Views: 560

Re: RPi 3 Driving an N-Channel MOSFET

Well, here's what I did last time: I just used an old 74HCT04 chip from the parts bin, added bypass cap and pullups to the inputs. 74HCT series have 3.3V CMOS compatible inputs and they have a totem-pole output at 5V TTL. They can source roughly 20 mA, much more than a Pi, too, so you can charge the...
by lb
Tue Dec 15, 2020 4:39 pm
Forum: General discussion
Topic: RPi 3 Driving an N-Channel MOSFET
Replies: 15
Views: 560

Re: RPi 3 Driving an N-Channel MOSFET

Vgs(th) is the *threshold* voltage, like the name says. You can't drive a lot of current through a MOSFET if it barely switches on. The datasheet should have a plot of maximum current vs Vgs. In your specific case, it looks like there's not a lot of room in the worst case, and depending on your use ...
by lb
Thu Nov 12, 2020 4:53 pm
Forum: General discussion
Topic: Non-Official Power Supply
Replies: 11
Views: 484

Re: Non-Official Power Supply

Well, maybe newer models are more resilient, but with Raspberry Pi 2/3 I had significant issues (not just with peripherals, but with overall reliability) whenever voltage dropped below ~4.2V.
by lb
Thu Nov 12, 2020 11:18 am
Forum: General discussion
Topic: Non-Official Power Supply
Replies: 11
Views: 484

Re: Non-Official Power Supply

The usual problem with (cheap) USB chargers is that they don't really perform up to spec, or that they have significant voltage droop at higher currents. The Raspberry Pi is quite sensitive to voltage droop, a smartphone or a power bank typically is not.
by lb
Wed Nov 04, 2020 12:33 pm
Forum: General discussion
Topic: Thread scheduling and optimising performance
Replies: 1
Views: 122

Re: Thread scheduling and optimising performance

You can set CPU affinity, e.g. with pthread's pthread_setaffinity_np() function. Normally this shouldn't be required, though. Are the thread really CPU bound? Maybe they're doing some I/O and that confuses the scheduler?
by lb
Wed Nov 04, 2020 12:20 pm
Forum: General discussion
Topic: I delidded my PI 4 and this happend...
Replies: 4
Views: 382

Re: I delidded my PI 4 and this happend...

I don't think delidding makes a lot of sense on the Pi... Anyway, it's likely some kind of decoupling capacitor. The exact value is probably not critical, perhaps you're going to see degraded EMC. Overclocking headroom may also be reduced due to degraded power stability. If you want to fix it, repla...
by lb
Wed Nov 04, 2020 8:35 am
Forum: General discussion
Topic: Raspberry Pi 4B performance question
Replies: 17
Views: 1012

Re: Raspberry Pi 4B performance question

mleoni wrote:
Wed Nov 04, 2020 8:30 am
Thanks for the input! I'm running the latest raspbian from a class 10 micro SD.
I use mainly Firefox 78 (not the one from the repos).
Firefox on Raspberry Pi only uses software decoding. You should use the customized version of Chromium for improved performance.
by lb
Wed Nov 04, 2020 8:34 am
Forum: General discussion
Topic: Raspberry Pi 4B performance question
Replies: 17
Views: 1012

Re: Raspberry Pi 4B performance question

Hardware acceleration is still far from perfect on the Pi, unfortunately. It's pretty tricky to get this working with a full-fledged browser. The Chromium browser that Raspbian ships with offloads video decoding, but as far as I can tell, the actual video rendering path isn't properly accelerated. S...
by lb
Tue Nov 03, 2020 8:04 am
Forum: Raspberry Pi 400
Topic: The Raspberry Pi 400 thread!
Replies: 1037
Views: 80797

Re: The Raspberry Pi 400 thread!

I did a quick power check on RPi4 4GB B1 stepping vs Pi400, running LibreELEC master with kernel 5.9.2 and Oct 29 firmware, and measured about 80mA/400mW less on Pi400 when kodi is idling on the main screen. Only GBit LAN and 1920x1200 monitor connected, wifi and BT disabled. Thank you for the test...
by lb
Tue Nov 03, 2020 7:57 am
Forum: General discussion
Topic: RPI 4 disappointment
Replies: 41
Views: 2614

Re: RPI 4 disappointment

SSDs can have surprisingly high peak power consumption, more than the Raspberry Pi itself. I can easily see a 2A power supply being inadequate. You may be able to configure the SSDs power/performance preference (Advanced Power Management) with hdparm if it supports that, but I'd simply get a more be...
by lb
Mon Nov 02, 2020 5:39 pm
Forum: Raspberry Pi 400
Topic: The Raspberry Pi 400 thread!
Replies: 1037
Views: 80797

Re: The Raspberry Pi 400 thread!

It's called binning and it's hardly new. Every chip manufacturer does it! Actually, it's more of a better clock gating in the C0 chip means we can power down more parts of the chip not ins use, which means less heat, which means more ability for higher clocks, which is boosted when combined with th...
by lb
Mon Nov 02, 2020 11:44 am
Forum: Raspberry Pi 400
Topic: The Raspberry Pi 400 thread!
Replies: 1037
Views: 80797

Re: The Raspberry Pi 400 thread!

Uh, what's so hard to understand about the clock frequency thing? The Raspberry Pi 4 is validated to work at 1.5 GHz. That is, the manufacturer tests the chips and guarantees that they work correctly up to 1.5 GHz. The Raspberry Pi 400 is validted to work at 1.8 GHz. That is, the manufacturer tests ...
by lb
Mon Nov 02, 2020 10:57 am
Forum: Raspberry Pi 400
Topic: The Raspberry Pi 400 thread!
Replies: 1037
Views: 80797

Re: The Raspberry Pi 400 thread!

The new revision of the SoC sounds interesting. I'm curious, has anyone done detailed power consumption tests yet? I couldn't find anything.
by lb
Wed Sep 02, 2020 1:00 pm
Forum: Advanced users
Topic: Possible SD transfert speed up on Pi 4 ?
Replies: 9
Views: 1203

Re: Possible SD transfert speed up on Pi 4 ?

It's slightly off-topic, but I still wonder why (apparently) the common SDR104 transfer mode is not supported by the Pi 4. Pretty much all SD controllers that support UHS transfer modes also support SDR104. Why was this omitted? Or maybe it wasn't, but it doesn't work reliably on the Pi 4? Does any...
by lb
Wed Sep 02, 2020 6:36 am
Forum: Advanced users
Topic: Possible SD transfert speed up on Pi 4 ?
Replies: 9
Views: 1203

Re: Possible SD transfert speed up on Pi 4 ?

It's slightly off-topic, but I still wonder why (apparently) the common SDR104 transfer mode is not supported by the Pi 4. Pretty much all SD controllers that support UHS transfer modes also support SDR104. Why was this omitted? Or maybe it wasn't, but it doesn't work reliably on the Pi 4? Does anyo...
by lb
Fri Nov 22, 2019 10:53 am
Forum: Advanced users
Topic: DVFS Firmware
Replies: 98
Views: 21891

Re: DVFS Firmware

Cool stuff! I've been waiting for this. After all there has been various commits in the past that pointed to ongoing work. :) I don't have a Pi 4 handy right now, does anyone have any numbers, e.g. current draw, before and after in idle and mixed load states yet? There's some power stuff in this ar...
by lb
Fri Nov 22, 2019 10:35 am
Forum: Advanced users
Topic: DVFS Firmware
Replies: 98
Views: 21891

Re: DVFS Firmware

Cool stuff! I've been waiting for this. After all there has been various commits in the past that pointed to ongoing work. :) I don't have a Pi 4 handy right now, does anyone have any numbers, e.g. current draw, before and after in idle and mixed load states yet? Edit: for anyone interested, I found...

Go to advanced search