Reduce touch overhead and cap frame rate at 24 FPS

lib/ft6336u/ft6336u.c

@@ -27,8 +27,9 @@ static bool ft6336u_read_reg(uint8_t reg, uint8_t *value) {
             continue;
         }
         
-        // Add delay after write, before read (like Arduino library does)
-        sleep_us(10000);  // 10ms delay
+        // Short settle time between register address write and read.
+        // 10ms here heavily throttles touch sampling during hold/move.
+        sleep_us(100);  // 0.1ms
         
         result = i2c_read_blocking(g_config->i2c, FT6336U_ADDR, value, 1, false);
         if (result == 1) {
@@ -50,8 +51,9 @@ static bool ft6336u_read_regs(uint8_t reg, uint8_t *buf, size_t len) {
             continue;
         }
         
-        // Add delay after write, before read (like Arduino library does)
-        sleep_us(10000);  // 10ms delay
+        // Short settle time between register address write and read.
+        // 10ms here heavily throttles touch sampling during hold/move.
+        sleep_us(100);  // 0.1ms
         
         result = i2c_read_blocking(g_config->i2c, FT6336U_ADDR, buf, len, false);
         if (result == (int)len) {

lib/input_manager.cpp

@@ -40,6 +40,8 @@ bool InputManager::has_buttons() const {
 
 InputEvent InputManager::process_touch_input(uint32_t* last_time) {
     InputEvent event = {INPUT_NONE, 0, 0, 0, 0, 0, false};
+    const uint32_t now = to_ms_since_boot(get_absolute_time());
+    static constexpr uint32_t ACTIVE_TOUCH_SAMPLE_INTERVAL_MS = 8;
     
     // Process immediately on IRQ, and continue sampling while a touch is active.
     // Some controllers only IRQ on edge transitions, so move events require polling.
@@ -47,16 +49,26 @@ InputEvent InputManager::process_touch_input(uint32_t* last_time) {
         return event;  // No touch event
     }
 
+    // While a touch session is active, avoid reading touch hardware every loop
+    // iteration. IRQ edges (down/up) still bypass this throttle for responsiveness.
+    if (!touch_interrupt_flag && *last_time != 0) {
+        uint32_t elapsed = now - last_touch_sample_ms;
+        if (elapsed < ACTIVE_TOUCH_SAMPLE_INTERVAL_MS) {
+            return event;
+        }
+    }
+
     // Always validate via controller state instead of relying on edge flag alone.
     // Edge chatter can flip touch_event_down without a real touch transition.
     TouchData touch_data;
     if (!touch || !touch->read_touch(&touch_data)) {
+        last_touch_sample_ms = now;
         touch_interrupt_flag = false;
         return event;
     }
 
+    last_touch_sample_ms = now;
     touch_interrupt_flag = false;
-    uint32_t now = to_ms_since_boot(get_absolute_time());
 
     // No active touch points: require consecutive empty reads before release to
     // avoid false TOUCH_UP events from transient controller jitter.
@@ -65,6 +77,7 @@ InputEvent InputManager::process_touch_input(uint32_t* last_time) {
             no_touch_samples++;
             if (no_touch_samples >= 2) {
                 *last_time = 0;
+                last_touch_sample_ms = 0;
                 no_touch_samples = 0;
                 event.type = INPUT_TOUCH_UP;
                 event.valid = true;

lib/input_manager.h

@@ -97,6 +97,8 @@ public:
 private:
     LowLevelTouch* touch;
     const GameConfig* config;
+    // Last time we sampled touch over I2C while a touch session is active.
+    uint32_t last_touch_sample_ms = 0;
     // Consecutive touch_count==0 samples while a touch session is active.
     // Used to suppress false TOUCH_UP events from transient touch controller jitter.
     uint8_t no_touch_samples = 0;