ESP32-C6 Power Consumption: Arduino vs. Zephyr vs. ESP-IDF Comparison
qoitech.com
qoitech.com
One problem with -O3 is that it disregards any effects of the cache (and yes, ESP32s have a bit of cache memory). I recommend using -Os as the default optimization level, as it often has the same or almost the same performance benefits as -O3. Less cache pressure is beneficial, especially for bigger applications, and the smaller code size is of course nice on embedded systems that have limited amounts of flash storage. If you know some specific functions or source files are performance sensitive, you can use pragmas to change optimization for those:
#pragma GCC optimize("O3")
GCC has historically been a bit of a pig about -Os, my favorite example is on x86 where it will emit a runtime divide for a division by a compile time constant power of two because it saves a byte of text!
int fn(int n)
{
return n / 8;
}
0000000000000000 <fn>:
0: 89 f8 mov %edi,%eax
2: b9 08 00 00 00 mov $0x8,%ecx
7: 99 cltd
8: f7 f9 idiv %ecx
a: c3 ret
0000000000000000 <fn>:
0: 8d 47 07 lea 0x7(%rdi),%eax
3: 85 ff test %edi,%edi
5: 0f 49 c7 cmovns %edi,%eax
8: c1 f8 03 sar $0x3,%eax
b: c3 ret It highlights that an idle loop in Arduino is energetically detrimental.
But one thing the article didn't point out is what hardware peripherals each firmware activated by default. Eg, activating UART might use default pins and activate an UART RX on a pin, which might incur a mA-order penalty. Hence, a useful first step in optimizing power is to identify what functionality you need and ensure all else is always powered down (eg uart rx, clocks and timers, radio peripherals.
Unsurprisingly, the old, non-standard, encumbered architecture is not missed.
I've not gotten around to trying, but I assume using deep sleep while waking up to batch send data with infrequent updates would be key.