XIAO RA4M1 power consumption in software standby mode still ~8 mA

Products & Technology XIAO
#1

hello,

I can’t get anywhere near the stated 45 uA!
SBYCR.SSBY bit is 1 ( software standby mode)
DMAST.DMST and DTCST.DTCST bits set to 0
OSTDCR.OSTDE = 0 (oscillation stop detection off)
Timers AGT 0 and AGT 1 are stopped.

All according to RENESAS RA4M1 Group Users Manual page 190 „Transition to Software Standby Mode“

After executing the WFI instruction current falls from 18 to 8 mA.

Measured at VBAT 3.7 V connected directly, no USB connection, all pins set as outputs low, according to RENESAS RA4 Quick Design Guide page 39 „unused pins“

If anyone could help me, I would be very grateful!

My project is a „Word Watch“ with e-paper display and time announcement, optional radiation detector.

Best regards
Armin

#2

hello,

I finally found out myself:

“The register write protection function protects important registers from being overwritten because of software errors. The
registers to be protected are set with the Protect Register (PRCR).”

Page 224 RENESAS RA4M1 Group Users Manual
in my case: R_SYSTEM → PRCR = 0xA503;
I measure now 40 uA!!! :heart_eyes:https://forum.seeedstudio.com/images/emoji/twitter/heart_eyes.png?v=12

Best Regards
Armin

2 Likes
#3

Hi there,

Nice work , pushing through the documentation is a chore and getting the result is Awesome.
Please mark it as the solution so others can find it and again , thanks for contributing. :+1:

GL :slight_smile: PJ :v:

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