Deep Software Standby mode possible for an Arduino UNO R4 Minima board? about arduino-uno-r4-wake_from_interrupt-and-system-clock-switching

[FUEL4EP]

Thanks a lot for your precise and swift answers, Susan.

[TriodeGirl]

Hi, thanks for your questions.
a) Yes there is, but it is complicated and one really needs to be using the resources provided by Renesas with their e2studio. The code I show is an easy way to get into the basic low power state within the scope of the Arduino IDE.
b) One should be able to get very low powers, but as per a) depends. The RA4M1 datasheet section 10. Low Power Modes gives the info.
https://www.renesas.com/us/en/document/mah/renesas-ra4m1-group-users-manual-hardware?r=1054146
c) LEDS, yes absolutely. The prime culprit is the power ON LED which takes a whopping 8mA or more. I rewired the connection to USB +5V input before the Schottky diode, so the LED is only one when the board is connected to a computer. Plus changed the series-resistor. The other LED on P13 also needs attention, as it significantly loads the SCLK line beyond the RA4M1's pin specification.
Hope this helps.
Best,
Susan.