fix: rebuild stale CAN map on firmware upgrade (new tmpobcmax canary)

The openinverter single-shot MapMessages() guard was using Param::hwaclim
as a "is the map valid" canary. hwaclim has been in every firmware version
for years, so on every upgrade the guard finds it in the saved flash map
and short-circuits — new AddRecv/AddSend entries in chargercan.cpp never
make it into the live canMap.

Symptom on the -S5 bench (verified via openinverter web UI spot values):
tmpobcmax, c1*/c2*/c3* per-module receives, and canenable/idcspnt/udclim
CHAdeMO RX entries were all unmapped despite being in current source.
The Polarity app saw zero charger temperature, zero per-module
current/voltage, and tmpobcmax=0 on 0x211 byte 7.

Fix: switch the canary from hwaclim -> tmpobcmax (added in -S5, never
present in older saved maps) and uncomment canMap->Clear() so the
rebuild starts clean. The early-return guard still kicks in on every
subsequent boot once tmpobcmax is in the map, preserving the original
intent of letting user customizations persist across reboots.

Also bumps VERSTR S5 -> S6 so the openinverter web UI labels this
firmware distinctly from the prior -S5 flash.

#minor

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -4,3 +4,4 @@ stm32_charger*
 linker.map
 *.layout
 *.out
+.DS_Store

include/param_prj.h

@@ -47,7 +47,7 @@
    3. Display values
  */
 //Next param id (increase when adding new parameter!): 24
-//Next value Id: 2051
+//Next value Id: 2052
 /*              category     name         unit       min     max     default id */
 #define PARAM_LIST \
     PARAM_ENTRY(CAT_CHARGER, idclim,      "A",       0,      45,     45,     3   ) \
@@ -108,6 +108,7 @@
     VALUE_ENTRY(c3iac,       "A",     2034 ) \
     VALUE_ENTRY(c3udc,       "V",     2035 ) \
     VALUE_ENTRY(c3idc,       "A",     2036 ) \
+    VALUE_ENTRY(tmpobcmax,   "°C",    2051 ) \
     VALUE_ENTRY(test_time,   "s",     3000 ) \
     VALUE_ENTRY(test_timer_flag,   "X",     3001 ) \
     VALUE_ENTRY(test_timer_icvalue,   "X",     3002 ) \
@@ -126,9 +127,9 @@
 #define CAT_COMM     "Communication"
 
 // SKUDAK customization suffix: bump on every Skudak-side change so the OpenInverter
-// web UI shows a distinct version (e.g. "4=1.20.R-S3") and we can visually confirm
+// web UI shows a distinct version (e.g. "4=1.20.R-S4") and we can visually confirm
 // the right firmware is flashed. Match the stm32-sine -S<N> convention.
-#define VERSTR STRINGIFY(4=VER-S3)
+#define VERSTR STRINGIFY(4=VER-S6)
 
 /***** enums ******/
 

src/chargercan.cpp

@@ -108,16 +108,19 @@ void ChargerCAN::MapMessages(CanMap* can)
    can->AddRecv(Param::vcuchglim, 0x212, 0, 8, 1);
 
    /***** SKUDAK VCU telemetry (0x211) — SKUDAK-448 expanded charger telemetry *****/
-   // Byte 0:    state (0=Off, 1=WaitStart, 2=Enable, 3=Activate, 4=Run, 5=Stop)
-   // Bytes 1-2: udc (V, gain=1)
-   // Bytes 3-4: idc (0.1A, gain=10)
-   // Byte 5:    uaux (decivolts, gain=10) — 12V aux battery rail
-   // Byte 6:    soc (%, gain=1)
-   // Byte 7:    reserved
+   // Byte 0:    state     (0=Off, 1=WaitStart, 2=Enable, 3=Activate, 4=Run, 5=Stop)
+   // Bytes 1-2: udc       (V, gain=1)
+   // Bytes 3-4: idc       (0.1A, gain=10)
+   // Byte 5:    uaux      (decivolts, gain=10) — 12V aux battery rail
+   // Byte 6:    soc       (%, gain=1)
+   // Byte 7:    tmpobcmax (°C, gain=1, offset=-40)  — worst-case across all
+   //                       9 OBC probes; matches Tesla OBC's own CAN offset
+   //                       so receivers can decode with the same formula.
    // Consumed by stm32-hal-vcu Core/Src/main.c CHARGER_CAN_ID_OI_OBC_AUX handler.
-   can->AddSend(Param::state, 0x211,  0, 8,  1);
-   can->AddSend(Param::udc,   0x211,  8, 16, 1);
-   can->AddSend(Param::idc,   0x211, 24, 16, 10);
-   can->AddSend(Param::uaux,  0x211, 40, 8,  10);
-   can->AddSend(Param::soc,   0x211, 48, 8,  1);
+   can->AddSend(Param::state,     0x211,  0, 8,  1);
+   can->AddSend(Param::udc,       0x211,  8, 16, 1);
+   can->AddSend(Param::idc,       0x211, 24, 16, 10);
+   can->AddSend(Param::uaux,      0x211, 40, 8,  10);
+   can->AddSend(Param::soc,       0x211, 48, 8,  1);
+   can->AddSend(Param::tmpobcmax, 0x211, 56, 8,  1, 40);  // offset 40 → wire byte = temp + 40
 }

src/main.cpp

@@ -77,6 +77,32 @@ static void Ms100Task(void)
 
    EvseRead();
 
+   // SKUDAK: derive a single "worst case" OBC temperature for downstream
+   // consumers (Polarity VCU broadcasts it on STATUS_SCREEN bytes 23/26).
+   // Aggregates the 9 per-module probes the Tesla OBC publishes on CAN
+   // 0x237/0x239/0x23B — max wins. Modules without a sensor read -40 °C
+   // (the DBC offset; raw byte 0); we ignore those so an absent module
+   // doesn't drag the worst-case down. If no probes are valid we leave
+   // tmpobcmax at -40 °C, which the VCU will display as "—".
+   {
+      const Param::PARAM_NUM probes[] = {
+         Param::c1tmp1, Param::c1tmp2, Param::c1tmpin,
+         Param::c2tmp1, Param::c2tmp2, Param::c2tmpin,
+         Param::c3tmp1, Param::c3tmp2, Param::c3tmpin,
+      };
+      int worst   = -40;
+      bool any_ok = false;
+      for (unsigned i = 0; i < sizeof(probes) / sizeof(probes[0]); i++) {
+         int t = Param::GetInt(probes[i]);
+         if (t <= -40) continue;  // No sensor / module not present
+         if (!any_ok || t > worst) {
+            worst  = t;
+            any_ok = true;
+         }
+      }
+      Param::SetInt(Param::tmpobcmax, any_ok ? worst : -40);
+   }
+
    canMap->SendAll();
 }
 
@@ -88,10 +114,22 @@ static void MapChargerMessages()
    float dummyGain;
    bool dummyrx;
 
-   //check sample value, if it is mapped assume valid CAN map
-   if (canMap->FindMap(Param::hwaclim, dummyId, dummyOfs, dummyLen, dummyGain, dummyAdd, dummyrx)) return;
+   // SKUDAK: tmpobcmax is the canary for the -S5+ CAN-map schema. If it's
+   // already mapped, the persistent flash map was built by a firmware that
+   // included the full current set of mappings (including the OBC temp
+   // aggregate and all c1*/c2*/c3* receives) — return early so user
+   // customizations are preserved.
+   //
+   // If tmpobcmax is NOT mapped, the saved map is from an older firmware
+   // that didn't know about it. We must wipe and rebuild from current
+   // chargercan.cpp — without this the OpenInverter single-shot MapMessages()
+   // pattern silently leaves newer params un-mapped on every subsequent
+   // boot, even after flashing fresh firmware (the original guard keyed off
+   // hwaclim, which has existed since the very first version — so it always
+   // short-circuited on upgrade and the new entries were dead code).
+   if (canMap->FindMap(Param::tmpobcmax, dummyId, dummyOfs, dummyLen, dummyGain, dummyAdd, dummyrx)) return;
 
-   //canMap->Clear();
+   canMap->Clear();
 
    ChargerCAN::MapMessages(canMap);
 
@@ -158,7 +196,11 @@ extern "C" void tim2_isr(void)
    scheduler->Run();
 }
 
-extern "C" int main(void)
+// C++ forbids a linkage specification on `main` (-Wpedantic). The reset_handler
+// in libopencm3's vector.c forward-declares `int main(void)` with default
+// linkage and resolves it at link time by symbol name, so dropping `extern "C"`
+// here doesn't affect how main is invoked at boot.
+int main(void)
 {
    extern const TERM_CMD termCmds[];