diff --git a/OpticalChannelTester/Config.h b/OpticalChannelTester/Config.h
index 244b9ac..82d53de 100644
--- a/OpticalChannelTester/Config.h
+++ b/OpticalChannelTester/Config.h
@@ -5,6 +5,7 @@
 // ------------------------- Hardware configuration -------------------------
 // Enabled for the hand-wired prototype. Comment out for the production PCB.
 // Both profiles map S3 signals by physical header position with 5V/GND aligned.
+
 //#define MAKETKA
 
 // Select exactly one populated receiver circuit. Use
@@ -12,7 +13,7 @@
 #define BOARD_RX_INTERFACE_ADC 1
 #define BOARD_RX_INTERFACE_DIGITAL 2
 #ifndef BOARD_RX_INTERFACE
-#define BOARD_RX_INTERFACE BOARD_RX_INTERFACE_DIGITAL
+#define BOARD_RX_INTERFACE BOARD_RX_INTERFACE_ADC
 #endif
 
 #if BOARD_RX_INTERFACE != BOARD_RX_INTERFACE_ADC && \
diff --git a/OpticalChannelTester/DriverTest.cpp b/OpticalChannelTester/DriverTest.cpp
index 0d46b83..583635e 100644
--- a/OpticalChannelTester/DriverTest.cpp
+++ b/OpticalChannelTester/DriverTest.cpp
@@ -10,15 +10,26 @@
 #include <esp32-hal-cpu.h>
 #include <soc/gpio_struct.h>
 #include <string.h>
+#if CONFIG_IDF_TARGET_ESP32C3
+#include <riscv/rv_utils.h>
+#endif
 
 static inline uint32_t IRAM_ATTR maskAllInterrupts() {
+#if CONFIG_IDF_TARGET_ESP32C3
+  return RV_CLEAR_CSR(mstatus, MSTATUS_MIE);
+#else
   uint32_t state;
   asm volatile("rsil %0, 15" : "=a"(state) :: "memory");
   return state;
+#endif
 }
 
 static inline void IRAM_ATTR restoreInterrupts(uint32_t state) {
+#if CONFIG_IDF_TARGET_ESP32C3
+  RV_SET_CSR(mstatus, state & MSTATUS_MIE);
+#else
   asm volatile("wsr %0, ps\nrsync" :: "a"(state) : "memory");
+#endif
 }
 
 void DriverEdgeStats::reset() {
@@ -193,7 +204,7 @@ void IRAM_ATTR DriverTest::pollTaskLoop() {
   constexpr uint32_t PIN_MASK = (1UL << GPIO_PWM) | (1UL << GPIO_RX);
   for (;;) {
     ulTaskNotifyTake(pdTRUE, portMAX_DELAY);
-    uint32_t levels = GPIO.in & PIN_MASK;
+    uint32_t levels = GPIO.in.val & PIN_MASK;
     uint32_t nextStart = 0;
     uint32_t windowEnd = 0;
     uint32_t lastTxStart = 0;
@@ -205,7 +216,7 @@ void IRAM_ATTR DriverTest::pollTaskLoop() {
     uint32_t interruptState = 0;
 
     auto sampleOnce = [&]() {
-      const uint32_t current = GPIO.in & PIN_MASK;
+      const uint32_t current = GPIO.in.val & PIN_MASK;
       if (current == levels) return;
       const uint32_t now = esp_cpu_get_cycle_count();
       const uint32_t changed = current ^ levels;
@@ -636,8 +647,7 @@ void IRAM_ATTR DriverTest::recordRaw(uint32_t tick, bool rising,
     return;
   }
   ring_[write] = {tick, rising, source};
-  asm volatile("memw" ::: "memory");
-  ringWrite_ = next;
+  __atomic_store_n(&ringWrite_, next, __ATOMIC_RELEASE);
 }
 
 size_t DriverTest::readRaw(TimedEvent *events, size_t capacity,
diff --git a/PCB/OptoTest.PcbDoc b/PCB/OptoTest.PcbDoc
index ab9aaa2..a5c0e51 100644
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diff --git a/PCB/OptoTest.SchDoc b/PCB/OptoTest.SchDoc
index fbedecc..fbc66d7 100644
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