#include <limits.h>

[RatGit]

I had to add the following #include to system.h in order to use the library under PlatformIO

#include <limits.h> // Defines ULONG_MAX etc, (required by samd21lpe library)

[jnsbyr]

Thanks for the info.

Tried to verify it but failed. Don't have my previous build environment any more - it was Arduino IDE 1.8.X. Tried PlatformIO with this platformio.ini:

[env]
framework = arduino
platform_packages =
   framework-arduino-samd-seeed @ 1.8.5
   
[env:seeed_xiao_samd]
platform = https://github.com/Seeed-Studio/platform-seeedboards.git
board = seeed-xiao-samd

... but this does not work as it assumes it is a regular Arduino project and not an Arduino library.

How does your platformio.ini look like? Did you have to change the directory structure?

[RatGit]

I've just added my instructions for installing under PlatformIO at: #3
(This includes the changes to the "platformio.ini" file)

Everything compiles Ok, but I'm still verifying that it's doing what its supposed to... Will keep you updated.

[RatGit]

So I've compiled the "tc_blink_standby" example under PlatformIO using my "Alternative Method". Unfortunately, my board still draws 740 microAmps. Using my own code, I've managed to get this down to 170 microAmps, but am still a long way from the few microAmps that I need :(

My next approach will be do it in the Arduino IDE as per your original instructions and try to duplicate your results.

Note: I'm using the same Seeed Studio XIAO SAMD21 module as you and have removed the Power LED bias resistor R6, but left the XC6206P332MR LDO connected so that I can continue to program the board through the USB port.

[RatGit]

BTW: My "platformio.ini" file currently looks like this:

[env:seeed_xiao]
platform = atmelsam
board = seeed_xiao
framework = arduino
build_flags =
-DARDUINO_SAMD_VARIANT_COMPLIANCE=10600
-DF_CPU=6000000L
platform_packages =
framework-arduino-samd-seeed @ file:///home/username/.platformio/packages/framework-arduino-samd-seeed-lpe
framework-arduino-samd-seeed-lpe @ https://github.com/RatGit/ArduinoCore-samd-lpe.git
; framework-arduino-samd-seeed-lpe @ file:///home/username/.platformio/packages/framework-arduino-samd-seeed-lpe

[jnsbyr]

Unfortunately, my board still draws 740 microAmps. Using my own code, I've managed to get this down to 170 microAmps, but am still a long way from the few microAmps that I need :(

It is tough going to get down to µAmps and µWatts. Just pushed some real world results from early 2024. Have a look at the README of my solar DHT test project. The prototype is still on my desk and working most of the year with no power input except a mix of low ambient (90 %) and medium artificial (10 %) light.

The board can really do 2 µA in standby with the modifications described in the README, but it requires disconnecting the LDO. Whenever necessary I placed a needle temporarily between board and the lifted pin when requiring USB power. But this will not work indefinitely as it bends the pin slightly every time and it will break off sooner or later.

So if you have achieved 170 µA with your own approach while active there is not much to complain, but if you have 170 µA in standby there is room for improvement.

BTW I started calculating (average) µWatts instead of (current) µAmps to get a better idea about (average) battery drain, as the solar DHT is in standby most of the time, but the periodic power draw caused by the MCU, DHT sensor, transmitter and display is short (130 ms) but high (25 mA) in comparison.

[jnsbyr]

Tried your platformio.ini, but still won't work for me. Using Windows, but don't think that is the reason. Build output:

Linking .pio\build\seeed_xiao_samd\firmware.elf
.pio\build\seeed_xiao_samd\libFrameworkArduino.a(main.cpp.o): In function `_real_body()':
main.cpp:(.text._Z10_real_bodyv+0x2): undefined reference to `setup'
main.cpp:(.text._Z10_real_bodyv+0x6): undefined reference to `loop'
collect2.exe: error: ld returned 1 exit status

As mentioned above, this looks like a regular Arduino INO build to me (setup, loop), although this is a library. How to make PlatformIO treat it like a library?

[jnsbyr]

Got the import hint from Gemini: One must build an example application to make PlatformIO build an Arduino library.

To use the current Arduino library directory structure instead of the default PlatformIO directory structure some additional settings are required (src_dir, lib_extra_dirs):

[platformio]
src_dir = examples/tc_blink_standby

[env:seeed_xiao_samd]
framework = arduino
lib_extra_dirs = ..
platform = https://github.com/Seeed-Studio/platform-seeedboards.git
board = seeed-xiao-samd
platform_packages =
   framework-arduino-samd-seeed @ 1.8.4

This build works without adding an include of limits.h or climits to System.h.

[RatGit]

Got the import hint from Gemini

I use ChatGPT for my coding tips, I find Gemini seems to hallucinate more. :)

This build works without adding an include of limits.h or climits to System.h.

Likely a Windows/Linux thing...
Were you able to duplicate your power usage results? If so, would you be willing to share your code with me to try?

but if you have 170 µA in standby there is room for improvement.

Yeah this was in Standby... Basically I have disabled everything I could and am doing nothing.

Have a look at the README of my solar DHT test project

Thanks for the link, I will look over it carefully.

[RatGit]

So I was able to get down to 16 microAmps, (with the LDO regulator still connected)...

My problem was that the "tc_blink_standby" sketch was turning on LED3, then going to sleep and never exiting. I tried turning off LED3 first in the loop and got the expected low current.
(I don't know why I didn't initially notice the LED was still on... Probably too busy looking at the multimeter and scratching my head! :( )

My new problem now, is to determine why it never exits the "sleep" function?

[jnsbyr]

My new problem now, is to determine why it never exits the "sleep" function?

It should, but not while sleeping. You can see what happens, if you follow the code:

sleep(50); -> timer.wait(ms); -> System::sleep(); -> __WFI();

WFI is the ARM assembly command "wait for interrupt", doing most of the low power magic.

If your system never stops sleeping, the interrupt source is probably not setup correctly. Have a look at the documentation that are linked at the bottom of the README for background info. One reason could be that the clock of your interrupt source is not enabled. The call System::reducePowerConsumption() turns off most of the clocks/consumers. The one you need (e.g. timer) must be re-enabled explicitly. That is why the order of certain commands is important.

[RatGit]

At the moment I am testing your "tc_blink_standby" code example without any modifications...

Note: The "tc_blink_sleep_on_exit" also has the same issue but the "tc_blink_idle2" works fine.

Basically any examples that use the STANDBY mode never exit?

[RatGit]

Hi Jens,

You'll be pleased to learn that I have found and fixed the bug in both of the STANDBY mode code examples:

In both the "tc_blink_standby" and "tc_blink_sleep_on_exit" code examples, the following line is missing the "durationScale" argument value:

timer.enable(4, GCLKGEN_ID_1K, 1024, TimerCounter::DIV1, TimerCounter::RES16, true);

It should be:
timer.enable(4, GCLKGEN_ID_1K, 1024, TimerCounter::DIV1, TimerCounter::RES16, 1000, true);

• You’re unintentionally passing true as the "durationScale" value, which becomes a 1 second scaling.
• The "runStandby" flag is not enabled, so the timer stops running in STANDBY mode.

I hope this helps... I think your library is a huge improvement on any other, and I appreciate the effort you must have expended upon it.

Keith.

PS. Why did you choose GCLK Generator ID = 6 in your example?
const byte GCLKGEN_ID_1K = 6;