diff --git a/frontend/src/simulation/RP2040Simulator.ts b/frontend/src/simulation/RP2040Simulator.ts
index 8a666b84..dd84a0c2 100644
--- a/frontend/src/simulation/RP2040Simulator.ts
+++ b/frontend/src/simulation/RP2040Simulator.ts
@@ -145,6 +145,12 @@ export class IdleSpinDetector {
 export type RP2040I2CDevice = I2CDevice;
 
 export class RP2040Simulator {
+  // Digital inputs are driven from the SPICE solve (connectDigitalInputsToMcu)
+  // for source-backed nets, so digitalRead reflects real wiring (a GP pin wired
+  // to a rail / button reads the right level). Floating nets are left to the
+  // part layer, so event-driven parts (encoder/keypad/…) keep working. Mirrors
+  // the AVR fix; the connector + sourcedNets gating are board-agnostic.
+  readonly spiceDrivenInputs = true;
   private rp2040: RP2040 | null = null;
   private running = false;
   private animationFrame: number | null = null;
diff --git a/frontend/src/simulation/spice/connectDigitalInputsToMcu.ts b/frontend/src/simulation/spice/connectDigitalInputsToMcu.ts
index cd8f5f84..843a02e2 100644
--- a/frontend/src/simulation/spice/connectDigitalInputsToMcu.ts
+++ b/frontend/src/simulation/spice/connectDigitalInputsToMcu.ts
@@ -21,6 +21,8 @@
  */
 import { useSimulatorStore, getBoardSimulator, getBoardPinManager } from '../../store/useSimulatorStore';
 import { useElectricalStore } from '../../store/useElectricalStore';
+import { isStm32BoardKind } from '../../types/board';
+import { stm32PinNameToLinear } from '../Stm32Bridge';
 
 // 3.3 V LVCMOS thresholds with a hysteresis band so a node hovering near the
 // midpoint doesn't chatter. A pulled-up idle input sits at ~3.3 V and a
@@ -53,9 +55,13 @@ export function connectDigitalInputsToMcu(): () => void {
       const pm = getBoardPinManager(board.id);
       const driven = pm ? pm.getOutputPins() : new Set<number>();
       const prefix = `${board.id}:`;
+      // STM32 names pins PA0/PC13/… and its PinManager + setPinState key on the
+      // linear pin (port*16+pin); every other board uses plain GPIO numbers.
+      const isStm32 = isStm32BoardKind(board.boardKind);
       for (const [key, net] of pinNetMap) {
         if (!key.startsWith(prefix)) continue;
-        const gpio = gpioFromPinName(key.slice(prefix.length));
+        const pinName = key.slice(prefix.length);
+        const gpio = isStm32 ? stm32PinNameToLinear(pinName) : gpioFromPinName(pinName);
         if (gpio < 0) continue;
         if (driven.has(gpio)) continue; // the MCU drives this pin (digitalWrite)
         // Only drive pins whose net is backed by a real source/element (rail,
diff --git a/frontend/src/store/useSimulatorStore.ts b/frontend/src/store/useSimulatorStore.ts
index ff31dba4..3d9be4d1 100644
--- a/frontend/src/store/useSimulatorStore.ts
+++ b/frontend/src/store/useSimulatorStore.ts
@@ -600,6 +600,12 @@ function makePinPullHandler(boardId: string) {
 // minus the ESP32-only WiFi / proxy-resync machinery. ──────────────────────
 class Stm32BridgeShim {
   pinManager: PinManager;
+  // Digital inputs are driven from the SPICE solve (connectDigitalInputsToMcu)
+  // for source-backed nets — digitalRead reflects the real wiring instead of a
+  // part seed. The connector maps STM32 pin names (PA0, PC13) to the linear pin
+  // setPinState expects via stm32PinNameToLinear. Floating nets stay with the
+  // part layer. Mirrors the AVR / RP2040 fix.
+  readonly spiceDrivenInputs = true;
   onSerialData: ((ch: string) => void) | null = null;
   onPinChangeWithTime: ((pin: number, state: boolean, timeMs: number) => void) | null = null;
   onBaudRateChange: ((baud: number) => void) | null = null;