feat: add BAR unit support to TPMS RX app (#2988)

- Add bar() conversion method to Pressure class
- Convert pressure units system from boolean to enum (kPa, PSI, BAR)
- Add BAR option to pressure unit selector in UI
- Update settings manager to persist pressure unit preference
- Use ternary operators for compact pressure formatting

firmware/application/external/tpmsrx/tpms_app.cpp

@@ -47,7 +47,10 @@ std::string id(tpms::TransponderID id) {
 }
 
 std::string pressure(Pressure pressure) {
-    return to_string_dec_int(units_psi ? pressure.psi() : pressure.kilopascal(), 3);
+    return to_string_dec_int(
+        format::units_pressure == format::PressureUnit::PSI ? pressure.psi() : format::units_pressure == format::PressureUnit::BAR ? pressure.bar()
+                                                                                                                                   : pressure.kilopascal(),
+        3);
 }
 
 std::string temperature(Temperature temperature) {
@@ -122,10 +125,10 @@ TPMSAppView::TPMSAppView(NavigationView&) {
     options_band.set_by_value(receiver_model.target_frequency());
 
     options_pressure.on_change = [this](size_t, int32_t i) {
-        format::units_psi = (bool)i;
+        format::units_pressure = static_cast<format::PressureUnit>(i);
         update_view();
     };
-    options_pressure.set_selected_index(format::units_psi, true);
+    options_pressure.set_selected_index(static_cast<int>(format::units_pressure), true);
 
     options_temperature.on_change = [this](size_t, int32_t i) {
         format::units_fahr = (bool)i;

firmware/application/external/tpmsrx/tpms_app.hpp

@@ -42,7 +42,13 @@ namespace ui::external_app::tpmsrx {
 
 namespace format {
 
-static bool units_psi{false};
+enum class PressureUnit : int {
+    kPa = 0,
+    PSI = 1,
+    BAR = 2,
+};
+
+static PressureUnit units_pressure{PressureUnit::kPa};
 static bool units_fahr{false};
 
 } /* namespace format */
@@ -117,7 +123,7 @@ class TPMSAppView : public View {
         "rx_tpms",
         app_settings::Mode::RX,
         {
-            {"units_psi"sv, &format::units_psi},
+            {"units_pressure"sv, &format::units_pressure},
             {"units_fahr"sv, &format::units_fahr},
         }};
 
@@ -154,9 +160,10 @@ class TPMSAppView : public View {
 
     OptionsField options_pressure{
         {6 * 8, UI_POS_Y(0)},
-        3,
-        {{"kPa", 0},
-         {"PSI", 1}}};
+        4,
+        {{"kPa", static_cast<int>(PressureUnit::kPa)},
+         {"PSI", static_cast<int>(PressureUnit::PSI)},
+         {"BAR", static_cast<int>(PressureUnit::BAR)}}};
 
     OptionsField options_temperature{
         {10 * 8, UI_POS_Y(0)},

firmware/common/units.hpp

@@ -48,6 +48,10 @@ class Pressure {
         return kpa_ * 1000 / 6895;
     }
 
+    int bar() const {
+        return kpa_ / 100;
+    }
+
    private:
     int16_t kpa_;
 };