next iteration on display, still some artifacting issues, and ux with buttons states and updating

main/main.c

@@ -38,6 +38,14 @@ static const char *TAG = "main";
 /* Consecutive failed polls before the displayed reading is treated as stale. */
 #define STALE_AFTER_POLLS 2
 
+/*
+ * Trend arrow thresholds, per hour. Below these a reading renders as flat:
+ * a thermostat's indoor temp wobbles a couple of tenths continuously, and an
+ * arrow that flickers on noise is worse than none.
+ */
+#define TREND_TEMP_PER_HOUR_F     0.5f
+#define TREND_PRESS_PER_HOUR_INHG 0.02f
+
 /* Depth 8: a burst of taps while the network is slow should queue rather than
  * be dropped, but a user cannot meaningfully get more than a few ahead. */
 #define CMD_QUEUE_DEPTH 8
@@ -190,6 +198,29 @@ static void ha_task(void *arg)
             consecutive_failures = 0;
             have_reading = true;
 
+            /*
+             * Trend history is local: the device sees every reading anyway,
+             * so an /api/history query would be hundreds of JSON points to
+             * answer a question one ring buffer answers for free. History is
+             * lost on reboot; arrows reappear ~5 minutes later.
+             */
+            const uint32_t now_ms = xTaskGetTickCount() * portTICK_PERIOD_MS;
+            if (ha_data.indoor_temp_f.valid) {
+                ha_trend_feed(HA_TREND_CH_INDOOR, ha_data.indoor_temp_f.value, now_ms);
+            }
+            if (ha_data.outdoor_temp_f.valid) {
+                ha_trend_feed(HA_TREND_CH_OUTDOOR, ha_data.outdoor_temp_f.value, now_ms);
+            }
+            if (ha_data.pressure_inhg.valid) {
+                ha_trend_feed(HA_TREND_CH_PRESSURE, ha_data.pressure_inhg.value, now_ms);
+            }
+            ha_data.trend_indoor =
+                ha_trend_compute(HA_TREND_CH_INDOOR, TREND_TEMP_PER_HOUR_F, now_ms);
+            ha_data.trend_outdoor =
+                ha_trend_compute(HA_TREND_CH_OUTDOOR, TREND_TEMP_PER_HOUR_F, now_ms);
+            ha_data.trend_pressure =
+                ha_trend_compute(HA_TREND_CH_PRESSURE, TREND_PRESS_PER_HOUR_INHG, now_ms);
+
             ui_update(&ha_data);
             ui_set_stale(false);
 
@@ -227,14 +258,23 @@ void app_main(void)
     ESP_LOGI(TAG, "Thermostat HMI -- CrowPanel 7.0\" ESP32-S3 (800x480)");
 
     /*
-     * WiFi comes up FIRST, before the RGB panel exists.
+     * Panel BUFFERS first, WiFi second, panel SCAN-OUT third. Both orderings
+     * are load-bearing:
      *
-     * The panel's bounce-buffer ISR reads the framebuffer out of PSRAM, and
-     * PSRAM shares the cache with flash on the ESP32-S3. Bringing up NVS and
-     * the WiFi PHY writes calibration data to flash, which disables the cache
-     * and faults that ISR. Doing it here means every flash write is finished
-     * before the panel starts scanning.
+     *  - display_alloc() before WiFi: the bounce buffers need two contiguous
+     *    25.6KB internal DMA blocks, and WiFi's RX buffer churn fragments
+     *    the internal heap within seconds of association. Allocating from
+     *    the virgin heap is deterministic; observed otherwise as a
+     *    boot-loop with 84KB free and no block big enough.
+     *
+     *  - display_start() after WiFi: from the moment scan-out begins, the
+     *    bounce-refill ISR reads PSRAM continuously, and PSRAM shares the
+     *    cache with flash on the S3. NVS and WiFi PHY calibration write
+     *    flash; doing all of that before the first scan means the ISR can
+     *    never hit "Cache disabled but cached memory region accessed".
      */
+    ESP_ERROR_CHECK(display_alloc());
+
     const esp_err_t wifi_err = wifi_init_sta();
     if (wifi_err != ESP_OK) {
         ESP_LOGE(TAG, "WiFi not up yet -- polling starts when it connects");
@@ -254,7 +294,8 @@ void app_main(void)
     }
     i2c_bus_scan(TAG);
 
-    ESP_ERROR_CHECK(display_init());
+    /* Buffers were allocated before WiFi; this only starts scan-out. */
+    ESP_ERROR_CHECK(display_start());
 
     if (touch_init() != ESP_OK) {
         /* A dead touch panel should not stop the display from working -- but