From: Alex Maestas <git@se30.xyz>
Date: Sun, 17 Dec 2023 17:40:19 +0000 (+0000)
Subject: work around silicon erratum in SUPC/VREG
X-Git-Url: https://git.earman.xyz/?a=commitdiff_plain;h=68f38652273bd6356e35dfcec0949f6783009dcf;p=sensor-watch.git

work around silicon erratum in SUPC/VREG
---

diff --git a/watch-library/hardware/watch/watch_private.c b/watch-library/hardware/watch/watch_private.c
index 4cae3cc..20f4ee5 100644
--- a/watch-library/hardware/watch/watch_private.c
+++ b/watch-library/hardware/watch/watch_private.c
@@ -35,6 +35,10 @@ void _watch_init(void) {
 
     // Use switching regulator for lower power consumption.
     SUPC->VREG.bit.SEL = 1;
+    // work around a silicon erratum that causes the microcontroller to lock up on leaving standby:
+    // request that the voltage regulator run in standby, and also that it switch to PL0.
+    SUPC->VREG.bit.RUNSTDBY = 1;
+    SUPC->VREG.bit.STDBYPL0 = 1;
     while(!SUPC->STATUS.bit.VREGRDY); // wait for voltage regulator to become ready
 
     // check the battery voltage...