Raspberry Pi Forums

kadamski

You don't even have to populate the board with the SPI flash. Without the flash (or with empty flash), the board will behave the same as when bootsel was permanently pushed down. You can verify that the board works by plugging it to USB where it will start in the bootloader mode. You can also build ...

kadamski

ejolson wrote: ↑
Thu Jul 29, 2021 4:37 pm

It would appear the main thing to learn from the fairy tale is that not any vendor should market a single development environment as one size fit all. The embedded community is too diverse and experienced for that.

Exactly! That is why the aproch RPF decided to use is so good!

kadamski

As for, 'it will get improved over time', RPT position is that it's already working great on Windows and no improvement is necessary on their part. Well, somehow I don't see it like that. If they didn't care, they wouldn't take part in this discussion at all, and they do, quite heavily. They did al...

kadamski

This would include: - disable all ADCs - turn of RTC - ensure that all GPIOs are not in a pullup/pulldown configuration - ensure that all GPIOs are not set for "output" - there may be a way to disable GPIO banks (some other MCUs have this) - there may be a way to turn off the USB interfac...

kadamski

The SRAM arrays are responsible for a good chunk of the total static power dissipation, If that is the case then maybe in some future revisions of this chip or some new parts in the family, it would make sense to make it possible to fully power down some banks at the expense of loosing their conten...

kadamski

I think the approach RPF took for the pico-sdk is just great. While the microcontroller itself might not be the best fit for some of my projects, I just enjoy the development on this platform. I was and still am impressed on how well they did it and I am very happy they didn't use IDE approach. None...

kadamski

I soldered the flash back to be able to easily disable all the memories. The power consumption I got on dormant mode was ~390uA. After disabling all the memory banks via syscfg_hw->mempowerdown, it was reduced to 280uA. So all the memory banks seems to consume ~110uA of current. The flash itself (wh...

kadamski

Just for the records, I managed to make a testing setup. ~380uA was the best I could get with rp2040 on a minimal board, without flash, no pull resistors on the board - just the chip, some required capacitors and a crystal. I am measuring the current on the output of the linear regulator and I'm run...

kadamski

It would be a shame if someone did discount using an RP2040 because of the headline "180uA" figure if it can indeed go lower. Exactly. It seems like it should be possible to go lower than that, we just don't know how much lower. With current situation of chip shortage it is hard to measur...

kadamski

pidd wrote: ↑
Mon Jul 26, 2021 1:34 pm
RP2040 data sheet Section 5.4 (page 636), it is stated at 0.18mA typical

Also is is worth noting that the datasheet says:

For power consumption of the Raspberry Pi Pico, please see the Raspberry Pi Pico Datasheet.

So I assume this is the consumption of only RP2040, not the Pico board.

kadamski

Does going into dormant mode preclude running code in RAM rather than flash because of the 20nS recovery requirement of the RAM (=two clock cycles at 100MHz)? I'd presume the first thing it does is to read an instruction when triggered out of dormant mode? I would expect so. But you don't have to p...

kadamski

If you power SRAM off it does lose its contents, its not flash. You are right - it makes sense that if you power the memory down completely , it looses its content. The fact that it is SRAM only means that we don't have to refresh the memory. But the datasheet is stating the content is retained. So...

kadamski

So, to be clear, I'm not doing any direct comparisons, I am interested in understand what makes some micro controllers able to go into 1-digit uA current sleep and not others. at the cost of loosing the contents for a chunk of ram, you can probably get the power usage even lower The idea of RAM cons...

kadamski

If you come from the SBC world, the power consumption of the RP2040 seems great and you feel like it can work on a battery forever (compared to RPI, for example). If, on the other hand, you come from the microcontroller world, the 180uA in dormant mode seems very high - like at least one order of ma...

kadamski

Unfortunately, AFAIK it's not driver issue but hardware issue. As such, it may (but doesn't have to, maybe there is some workaround possible) be not fixable.

kadamski

You can also use software bitbanged GPIO driver. You need kernel recompilation for that currently, though. You can take a look at this thread for some more information.

kadamski

Seems to be working with my atmega328p, using exacly the same wiring as for linuxgpio driver. I was able to properly read fuses and program some basic blink application. Great job! The only problem I have found (but I believe it may be in spi driver, not in your code) is that if I use linuxgpio driv...

kadamski

Since you are using your own compiled kernel, you have to ensure that it is not overwriten by apt-get update. There are couple of ways you can achieve this. What I'm doing is to rename kernel.img to kernel-my.img and add kernel=kernel_my.img line to config.txt. This makes bootloader use kernel_my.im...

kadamski

When you update the system with apt-get, your kernel may be updated (and it seems it was the case). The kernel consists of kernel.img file in /boot/ directory and of modules files in /lib/modules directory. It seems that you only overrides kernel.img file and not modules files. This causes your inco...

kadamski

Check that you have w1-gpio and w1-therm kernel modules.

kadamski

This is exacly what I was expecting when writing my last post in this thread. Good to hear that you managed to figure out yourself how to compile those modules. And by the way, the answer from SE that you quoted is actually mine. Noticed that in the middle of reading it :)

kadamski

It's not distribution specific for sure. It may be kernel specific but I doubt it. I'm using latest raspbian image with my custom made kernel. And now that I think about this - this may be the cause of your problem. There is no gpio_pcf857x module in official raspberrypi's kernel. Are you able to lo...

kadamski

I think I should have an entry "gpioXXX" in /sys/class/gpio after initializing the chip but I continue having the initial entries... Yes, you should have additional gpioXXX directory in /sys/class/gpio. And it works perfectly fine for me. But it only appears if i specify first argument to...

kadamski

You can write anything you want as a frist argument to new_device. For example this wont give you an error: echo blah 0x20 > /sys/bus/i2c/devices/i2c-0/new_device Here's what I get from dmesg: i2c i2c-0: new_device: Instantiated device blah at 0x20 But of course it doesn't work. There is no driver f...

kadamski

Are you sure that your device is pcf8574 and not pcf8574a or pca8574? Try those two as a first argument to /sys/bus/i2c/devices/i2c-1/new_device. Hint, you can remove previously created device using

Code: Select all

echo 0x3a >  /sys/bus/i2c/devices/i2c-1/delete_device

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