Add CYD host PC info panel with serial SI protocol and LVGL bars.

ESP32 shows CPU/GPU/RAM/disk from host/send_sysinfo.ps1 over USB; firmware packages for 2.8 and 3.5 included.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/host_info.cpp

@@ -0,0 +1,152 @@
+#include "host_info.h"
+
+#include <Arduino.h>
+#include <cstdio>
+#include <cstring>
+
+static HostInfo g_info = {};
+static char g_line[384];
+static size_t g_len = 0;
+
+static void copy_trunc(char *dst, size_t dst_sz, const char *src) {
+  if (!dst || dst_sz == 0) {
+    return;
+  }
+  if (!src) {
+    dst[0] = '\0';
+    return;
+  }
+  strncpy(dst, src, dst_sz - 1);
+  dst[dst_sz - 1] = '\0';
+}
+
+static const char *find_field(const char *line, const char *key) {
+  // Look for |key=value| or start-of-string after "SI|"
+  const size_t klen = strlen(key);
+  const char *p = line;
+  while (p && *p) {
+    if (strncmp(p, key, klen) == 0 && p[klen] == '=') {
+      return p + klen + 1;
+    }
+    p = strchr(p, '|');
+    if (!p) {
+      break;
+    }
+    ++p;
+  }
+  return nullptr;
+}
+
+static void copy_field(char *dst, size_t dst_sz, const char *line, const char *key) {
+  const char *v = find_field(line, key);
+  if (!v) {
+    dst[0] = '\0';
+    return;
+  }
+  size_t n = 0;
+  while (v[n] && v[n] != '|' && n + 1 < dst_sz) {
+    dst[n] = v[n];
+    ++n;
+  }
+  dst[n] = '\0';
+}
+
+static float field_float(const char *line, const char *key, float fallback) {
+  const char *v = find_field(line, key);
+  if (!v || !*v) {
+    return fallback;
+  }
+  return (float)atof(v);
+}
+
+static void apply_line(const char *line) {
+  // SI|host=...|cpu=...|cpu%=..|gpu=...|gpu%=..|ram=used/total|disk=used/total
+  if (strncmp(line, "SI|", 3) != 0) {
+    return;
+  }
+
+  HostInfo next = g_info;
+  next.valid = true;
+  next.updated_ms = millis();
+
+  copy_field(next.host, sizeof(next.host), line, "host");
+  copy_field(next.cpu, sizeof(next.cpu), line, "cpu");
+  copy_field(next.gpu, sizeof(next.gpu), line, "gpu");
+  next.cpu_pct = field_float(line, "cpu%", next.cpu_pct);
+  next.gpu_pct = field_float(line, "gpu%", next.gpu_pct);
+
+  const char *ram = find_field(line, "ram");
+  if (ram) {
+    float u = 0, t = 0;
+    if (sscanf(ram, "%f/%f", &u, &t) == 2) {
+      next.ram_used_gb = u;
+      next.ram_total_gb = t;
+    }
+  }
+  const char *disk = find_field(line, "disk");
+  if (disk) {
+    float u = 0, t = 0;
+    if (sscanf(disk, "%f/%f", &u, &t) == 2) {
+      next.disk_used_gb = u;
+      next.disk_total_gb = t;
+    }
+  }
+
+  if (next.cpu_pct < 0) {
+    next.cpu_pct = 0;
+  }
+  if (next.cpu_pct > 100) {
+    next.cpu_pct = 100;
+  }
+  if (next.gpu_pct > 100) {
+    next.gpu_pct = 100;
+  }
+
+  g_info = next;
+}
+
+void host_info_begin() {
+  memset(&g_info, 0, sizeof(g_info));
+  g_info.gpu_pct = -1.0f;
+  g_info.valid = false;
+  g_len = 0;
+  g_line[0] = '\0';
+}
+
+bool host_info_poll() {
+  bool got = false;
+  while (Serial.available() > 0) {
+    const int c = Serial.read();
+    if (c < 0) {
+      break;
+    }
+    if (c == '\r') {
+      continue;
+    }
+    if (c == '\n') {
+      g_line[g_len] = '\0';
+      if (g_len > 0) {
+        apply_line(g_line);
+        got = g_info.valid;
+      }
+      g_len = 0;
+      continue;
+    }
+    if (g_len + 1 < sizeof(g_line)) {
+      g_line[g_len++] = (char)c;
+    } else {
+      // Overflow — drop line
+      g_len = 0;
+    }
+  }
+  return got;
+}
+
+const HostInfo &host_info_get() { return g_info; }
+
+bool host_info_is_live(uint32_t stale_ms) {
+  if (!g_info.valid) {
+    return false;
+  }
+  return (millis() - g_info.updated_ms) <= stale_ms;
+}

src/main.cpp

@@ -0,0 +1,52 @@
+#include <Arduino.h>
+#include <lvgl.h>
+
+#include "host_info.h"
+#include "pins.h"
+#include "touch.h"
+#include "ui.h"
+
+static constexpr uint32_t DRAW_BUF_SIZE =
+    (SCREEN_WIDTH * SCREEN_HEIGHT / DRAW_BUF_DIV * (LV_COLOR_DEPTH / 8));
+static uint32_t draw_buf[DRAW_BUF_SIZE / 4];
+
+void setup() {
+  Serial.setRxBufferSize(2048);
+  Serial.begin(460800);
+  delay(200);
+  Serial.println();
+  Serial.printf("LVGL %d.%d.%d | CYD Server Info\n", lv_version_major(),
+                lv_version_minor(), lv_version_patch());
+  Serial.println("BOOT_OK");
+  Serial.println("PROTO SI|host=..|cpu=..|cpu%=..|gpu=..|gpu%=..|ram=u/t|disk=u/t");
+  Serial.printf("heap=%u  BL=%d  panel=%dx%d ui=%dx%d\n",
+                (unsigned)ESP.getFreeHeap(), TFT_BL_PIN, SCREEN_WIDTH,
+                SCREEN_HEIGHT, UI_HOR_RES, UI_VER_RES);
+
+  pinMode(TFT_BL_PIN, OUTPUT);
+  digitalWrite(TFT_BL_PIN, HIGH);
+
+  touch_init();
+  host_info_begin();
+
+  lv_init();
+  lv_display_t *disp =
+      lv_tft_espi_create(SCREEN_WIDTH, SCREEN_HEIGHT, draw_buf, sizeof(draw_buf));
+  lv_display_set_rotation(disp, LV_DISPLAY_ROTATION_270);
+
+  lv_indev_t *indev = lv_indev_create();
+  lv_indev_set_type(indev, LV_INDEV_TYPE_POINTER);
+  lv_indev_set_read_cb(indev, touch_read_cb);
+  lv_indev_set_display(indev, disp);
+
+  ui_create();
+  Serial.printf("ui_ok heap=%u\n", (unsigned)ESP.getFreeHeap());
+}
+
+void loop() {
+  host_info_poll();
+  lv_timer_handler();
+  lv_tick_inc(5);
+  ui_tick();
+  delay(5);
+}

src/touch.cpp

@@ -0,0 +1,284 @@
+#include "touch.h"
+#include "pins.h"
+
+#include <Arduino.h>
+
+#if defined(CYD_BOARD_3248S035)
+#include <Wire.h>
+#endif
+
+/**
+ * 2.8": dedicated SoftSPI + BL/TR diagonal fix.
+ * 3.5C (3248S035C): capacitive GT911 on I2C SDA33/SCL32/INT21/RST25.
+ */
+
+int16_t g_dbg_phys_x = -1;
+int16_t g_dbg_phys_y = -1;
+int16_t g_dbg_logic_x = -1;
+int16_t g_dbg_logic_y = -1;
+bool g_dbg_touch_down = false;
+
+static int16_t clampi(int32_t v, int32_t lo, int32_t hi) {
+  if (v < lo) {
+    return (int16_t)lo;
+  }
+  if (v > hi) {
+    return (int16_t)hi;
+  }
+  return (int16_t)v;
+}
+
+#if defined(CYD_BOARD_3248S035)
+
+/* Minimal GT911 — no config rewrite (TAMC setResolution can hang Wire). */
+static uint8_t s_gt_addr = 0x5D;
+static constexpr uint16_t GT_POINT_INFO = 0x814E;
+static constexpr uint16_t GT_POINT_1 = 0x814F;
+
+static bool gt_write8(uint16_t reg, uint8_t val) {
+  Wire.beginTransmission(s_gt_addr);
+  Wire.write((uint8_t)(reg >> 8));
+  Wire.write((uint8_t)(reg & 0xFF));
+  Wire.write(val);
+  return Wire.endTransmission() == 0;
+}
+
+static bool gt_read(uint16_t reg, uint8_t *buf, uint8_t len) {
+  Wire.beginTransmission(s_gt_addr);
+  Wire.write((uint8_t)(reg >> 8));
+  Wire.write((uint8_t)(reg & 0xFF));
+  if (Wire.endTransmission(false) != 0) {
+    return false;
+  }
+  const uint8_t n = Wire.requestFrom(s_gt_addr, len);
+  if (n != len) {
+    return false;
+  }
+  for (uint8_t i = 0; i < len; i++) {
+    buf[i] = Wire.read();
+  }
+  return true;
+}
+
+static bool gt_probe(uint8_t addr) {
+  Wire.beginTransmission(addr);
+  return Wire.endTransmission() == 0;
+}
+
+/* TAMC-compatible address select: INT low => 0x5D, INT high => 0x14 */
+static void gt_hw_reset(bool addr_0x14) {
+  pinMode(CYD_GT911_INT, OUTPUT);
+  pinMode(CYD_GT911_RST, OUTPUT);
+  digitalWrite(CYD_GT911_INT, LOW);
+  digitalWrite(CYD_GT911_RST, LOW);
+  delay(10);
+  digitalWrite(CYD_GT911_INT, addr_0x14 ? HIGH : LOW);
+  delay(1);
+  digitalWrite(CYD_GT911_RST, HIGH);
+  delay(5);
+  digitalWrite(CYD_GT911_INT, LOW);
+  delay(50);
+  /* Backlight is GPIO27 — leave INT as input for polling / optional IRQ. */
+  pinMode(CYD_GT911_INT, INPUT);
+  delay(50);
+}
+
+static bool gt_find_addr() {
+  for (uint8_t a : {uint8_t(0x5D), uint8_t(0x14)}) {
+    if (gt_probe(a)) {
+      s_gt_addr = a;
+      return true;
+    }
+  }
+  return false;
+}
+
+void touch_init() {
+  Serial.println("Touch: GT911 I2C capacitive (3.5C) minimal");
+  Wire.begin(CYD_GT911_SDA, CYD_GT911_SCL);
+  Wire.setClock(100000);
+#if defined(WIRE_HAS_TIMEOUT) || defined(ESP32)
+  Wire.setTimeOut(50);
+#endif
+
+  if (!gt_find_addr()) {
+    Serial.println("GT911 not found — hw reset 0x5D");
+    gt_hw_reset(false);
+    if (!gt_find_addr()) {
+      Serial.println("GT911 not found — hw reset 0x14");
+      gt_hw_reset(true);
+      gt_find_addr();
+    }
+  }
+
+  Serial.printf("GT911 probe 0x5D=%s 0x14=%s using=0x%02X\n",
+                gt_probe(0x5D) ? "OK" : "no", gt_probe(0x14) ? "OK" : "no",
+                s_gt_addr);
+  Serial.printf("GT911 SDA=%d SCL=%d INT=%d RST=%d\n", CYD_GT911_SDA,
+                CYD_GT911_SCL, CYD_GT911_INT, CYD_GT911_RST);
+}
+
+void touch_read_cb(lv_indev_t * /*indev*/, lv_indev_data_t *data) {
+  uint8_t info = 0;
+  static uint32_t last_log = 0;
+  const bool do_log = (millis() - last_log > 200);
+
+  if (!gt_read(GT_POINT_INFO, &info, 1)) {
+    data->state = LV_INDEV_STATE_RELEASED;
+    g_dbg_touch_down = false;
+    if (do_log) {
+      last_log = millis();
+      Serial.println("TouchProbe GT911 I2C err");
+    }
+    return;
+  }
+
+  const uint8_t touches = info & 0x0F;
+  const bool buffered = (info & 0x80) != 0;
+
+  if (!buffered || touches == 0) {
+    if (buffered) {
+      gt_write8(GT_POINT_INFO, 0);
+    }
+    data->state = LV_INDEV_STATE_RELEASED;
+    g_dbg_touch_down = false;
+    return;
+  }
+
+  uint8_t pt[7];
+  if (!gt_read(GT_POINT_1, pt, 7)) {
+    gt_write8(GT_POINT_INFO, 0);
+    data->state = LV_INDEV_STATE_RELEASED;
+    g_dbg_touch_down = false;
+    return;
+  }
+  gt_write8(GT_POINT_INFO, 0);
+
+  const int16_t raw_x = (int16_t)(pt[1] | (pt[2] << 8));
+  const int16_t raw_y = (int16_t)(pt[3] | (pt[4] << 8));
+
+  /* Native 320x480 → LVGL 270. Mirror long axis so L/R matches UI
+   * (else preset 3 hits 10). Resulting UI ≈ (H-1-raw_y, raw_x). */
+  const int16_t nx = clampi(raw_x, 0, SCREEN_WIDTH - 1);
+  const int16_t ny = clampi(raw_y, 0, SCREEN_HEIGHT - 1);
+  const int16_t feed_x = (int16_t)((SCREEN_WIDTH - 1) - nx);
+  const int16_t feed_y = (int16_t)((SCREEN_HEIGHT - 1) - ny);
+  const int16_t ui_x = (int16_t)((SCREEN_HEIGHT - 1) - ny);
+  const int16_t ui_y = nx;
+
+  g_dbg_phys_x = raw_x;
+  g_dbg_phys_y = raw_y;
+  g_dbg_logic_x = ui_x;
+  g_dbg_logic_y = ui_y;
+  g_dbg_touch_down = true;
+
+  if (do_log) {
+    last_log = millis();
+    Serial.printf("Touch HIT GT911 raw(%d,%d) ~ui(%d,%d)\n", raw_x, raw_y,
+                  ui_x, ui_y);
+  }
+
+  data->point.x = feed_x;
+  data->point.y = feed_y;
+  data->state = LV_INDEV_STATE_PRESSED;
+}
+
+#else
+
+static void soft_write(uint8_t data) {
+  for (int i = 7; i >= 0; --i) {
+    digitalWrite(CYD_TOUCH_MOSI, (data >> i) & 1);
+    digitalWrite(CYD_TOUCH_CLK, HIGH);
+    delayMicroseconds(2);
+    digitalWrite(CYD_TOUCH_CLK, LOW);
+    delayMicroseconds(2);
+  }
+}
+
+static uint16_t soft_read12() {
+  uint16_t v = 0;
+  digitalWrite(CYD_TOUCH_CLK, HIGH);
+  delayMicroseconds(2);
+  digitalWrite(CYD_TOUCH_CLK, LOW);
+  delayMicroseconds(2);
+  for (int i = 0; i < 12; ++i) {
+    digitalWrite(CYD_TOUCH_CLK, HIGH);
+    delayMicroseconds(2);
+    v = (uint16_t)((v << 1) | (digitalRead(CYD_TOUCH_MISO) ? 1u : 0u));
+    digitalWrite(CYD_TOUCH_CLK, LOW);
+    delayMicroseconds(2);
+  }
+  return v;
+}
+
+static uint16_t xpt_read(uint8_t cmd) {
+  digitalWrite(CYD_TOUCH_CS, LOW);
+  soft_write(cmd);
+  uint16_t v = soft_read12();
+  digitalWrite(CYD_TOUCH_CS, HIGH);
+  return v;
+}
+
+void touch_init() {
+  pinMode(CYD_TOUCH_CS, OUTPUT);
+  pinMode(CYD_TOUCH_CLK, OUTPUT);
+  pinMode(CYD_TOUCH_MOSI, OUTPUT);
+  pinMode(CYD_TOUCH_MISO, INPUT);
+  pinMode(CYD_TOUCH_IRQ, INPUT);
+  digitalWrite(CYD_TOUCH_CS, HIGH);
+  digitalWrite(CYD_TOUCH_CLK, LOW);
+  Serial.println("Touch: SoftSPI + diagonal fix (BL/TR)");
+}
+
+void touch_read_cb(lv_indev_t * /*indev*/, lv_indev_data_t *data) {
+  uint16_t adc_x = xpt_read(0x90);
+  uint16_t adc_y = xpt_read(0xD0);
+  adc_x = (uint16_t)((adc_x + xpt_read(0x90)) / 2);
+  adc_y = (uint16_t)((adc_y + xpt_read(0xD0)) / 2);
+
+  const bool irq = (digitalRead(CYD_TOUCH_IRQ) == LOW);
+  const bool in_range =
+      (adc_x > 80 && adc_x < 4000 && adc_y > 80 && adc_y < 4000);
+
+  if (!in_range || (!irq && (adc_x < 200 || adc_y < 200))) {
+    data->state = LV_INDEV_STATE_RELEASED;
+    g_dbg_touch_down = false;
+    return;
+  }
+
+  const int16_t p_x = (int16_t)adc_x;
+  const int16_t p_y = (int16_t)(4095 - adc_y);
+
+  int16_t x = map(p_x, 200, 3700, 1, SCREEN_WIDTH);
+  int16_t y = map(p_y, 240, 3800, 1, SCREEN_HEIGHT);
+  x = clampi(x, 0, SCREEN_WIDTH - 1);
+  y = clampi(y, 0, SCREEN_HEIGHT - 1);
+
+  const int32_t old_ux = y;
+  const int32_t old_uy = (SCREEN_WIDTH - 1) - x;
+  int16_t ui_x = clampi((old_uy * (UI_HOR_RES - 1)) / (UI_VER_RES - 1), 0,
+                        UI_HOR_RES - 1);
+  int16_t ui_y = clampi((old_ux * (UI_VER_RES - 1)) / (UI_HOR_RES - 1), 0,
+                        UI_VER_RES - 1);
+
+  const int16_t feed_x = (int16_t)((SCREEN_WIDTH - 1) - ui_y);
+  const int16_t feed_y = ui_x;
+
+  g_dbg_phys_x = x;
+  g_dbg_phys_y = y;
+  g_dbg_logic_x = ui_x;
+  g_dbg_logic_y = ui_y;
+  g_dbg_touch_down = true;
+
+  static uint32_t last_log = 0;
+  if (millis() - last_log > 80) {
+    last_log = millis();
+    Serial.printf("Touch UI(%d,%d)\n", ui_x, ui_y);
+  }
+
+  data->point.x = feed_x;
+  data->point.y = feed_y;
+  data->state = LV_INDEV_STATE_PRESSED;
+}
+
+#endif

src/ui.cpp

@@ -0,0 +1,223 @@
+#include "ui.h"
+
+#include "host_info.h"
+#include "pins.h"
+
+#include <Arduino.h>
+#include <cstdio>
+#include <lvgl.h>
+
+static constexpr uint32_t COL_BG = 0x0B121A;
+static constexpr uint32_t COL_INK = 0xE8EEF4;
+static constexpr uint32_t COL_MUTED = 0x7A8B9C;
+static constexpr uint32_t COL_LINE = 0x1A2734;
+static constexpr uint32_t COL_OK = 0x3DDC97;
+static constexpr uint32_t COL_WARN = 0xE8B84A;
+static constexpr uint32_t COL_BAD = 0xE85D4C;
+static constexpr uint32_t COL_ACCENT = 0x4FC3F7;
+static constexpr uint32_t COL_BAR_BG = 0x162230;
+
+struct MetricRow {
+  lv_obj_t *lbl_tag;
+  lv_obj_t *lbl_name;
+  lv_obj_t *lbl_pct;
+  lv_obj_t *bar;
+};
+
+static lv_obj_t *scr = nullptr;
+static lv_obj_t *lbl_title = nullptr;
+static lv_obj_t *lbl_host = nullptr;
+static lv_obj_t *lbl_status = nullptr;
+static MetricRow row_cpu = {};
+static MetricRow row_gpu = {};
+static MetricRow row_ram = {};
+static MetricRow row_disk = {};
+static uint32_t last_paint_ms = 0;
+
+static int pct_of(float used, float total) {
+  if (total <= 0.01f) {
+    return 0;
+  }
+  int p = (int)((used * 100.0f) / total + 0.5f);
+  if (p < 0) {
+    p = 0;
+  }
+  if (p > 100) {
+    p = 100;
+  }
+  return p;
+}
+
+static uint32_t color_for_pct(int pct) {
+  if (pct >= 85) {
+    return COL_BAD;
+  }
+  if (pct >= 65) {
+    return COL_WARN;
+  }
+  return COL_OK;
+}
+
+static void style_bar(lv_obj_t *bar) {
+  lv_obj_set_style_bg_color(bar, lv_color_hex(COL_BAR_BG), LV_PART_MAIN);
+  lv_obj_set_style_bg_opa(bar, LV_OPA_COVER, LV_PART_MAIN);
+  lv_obj_set_style_radius(bar, 4, LV_PART_MAIN);
+  lv_obj_set_style_pad_all(bar, 0, LV_PART_MAIN);
+  lv_obj_set_style_bg_color(bar, lv_color_hex(COL_OK), LV_PART_INDICATOR);
+  lv_obj_set_style_bg_opa(bar, LV_OPA_COVER, LV_PART_INDICATOR);
+  lv_obj_set_style_radius(bar, 4, LV_PART_INDICATOR);
+  lv_bar_set_range(bar, 0, 100);
+  lv_bar_set_value(bar, 0, LV_ANIM_OFF);
+}
+
+static MetricRow make_row(lv_obj_t *parent, const char *tag, int y) {
+  MetricRow r = {};
+
+  r.lbl_tag = lv_label_create(parent);
+  lv_label_set_text(r.lbl_tag, tag);
+  lv_obj_set_style_text_color(r.lbl_tag, lv_color_hex(COL_ACCENT), 0);
+  lv_obj_set_style_text_font(r.lbl_tag, &lv_font_montserrat_14, 0);
+  lv_obj_set_pos(r.lbl_tag, UX(8), UY(y));
+
+  r.lbl_name = lv_label_create(parent);
+  lv_label_set_text(r.lbl_name, "—");
+  lv_label_set_long_mode(r.lbl_name, LV_LABEL_LONG_DOT);
+  lv_obj_set_width(r.lbl_name, UW(190));
+  lv_obj_set_style_text_color(r.lbl_name, lv_color_hex(COL_INK), 0);
+  lv_obj_set_style_text_font(r.lbl_name, &lv_font_montserrat_14, 0);
+  lv_obj_set_pos(r.lbl_name, UX(52), UY(y));
+
+  r.lbl_pct = lv_label_create(parent);
+  lv_label_set_text(r.lbl_pct, "--%");
+  lv_obj_set_style_text_color(r.lbl_pct, lv_color_hex(COL_MUTED), 0);
+  lv_obj_set_style_text_font(r.lbl_pct, &lv_font_montserrat_14, 0);
+  lv_obj_align(r.lbl_pct, LV_ALIGN_TOP_RIGHT, UX(-8), UY(y));
+
+  r.bar = lv_bar_create(parent);
+  lv_obj_set_size(r.bar, UI_HOR_RES - UW(16), UH(10));
+  lv_obj_set_pos(r.bar, UX(8), UY(y + 18));
+  style_bar(r.bar);
+
+  return r;
+}
+
+static void set_row_pct(MetricRow &r, int pct, const char *name, const char *right) {
+  if (r.lbl_name && name) {
+    lv_label_set_text(r.lbl_name, name);
+  }
+  if (r.lbl_pct && right) {
+    lv_label_set_text(r.lbl_pct, right);
+    lv_obj_set_style_text_color(r.lbl_pct, lv_color_hex(color_for_pct(pct)), 0);
+  }
+  if (r.bar) {
+    lv_bar_set_value(r.bar, pct, LV_ANIM_OFF);
+    lv_obj_set_style_bg_color(r.bar, lv_color_hex(color_for_pct(pct)),
+                              LV_PART_INDICATOR);
+  }
+}
+
+void ui_create() {
+  scr = lv_obj_create(nullptr);
+  lv_obj_set_style_bg_color(scr, lv_color_hex(COL_BG), 0);
+  lv_obj_set_style_bg_opa(scr, LV_OPA_COVER, 0);
+  lv_obj_clear_flag(scr, LV_OBJ_FLAG_SCROLLABLE);
+  lv_screen_load(scr);
+
+  lbl_title = lv_label_create(scr);
+  lv_label_set_text(lbl_title, "PC Monitor");
+  lv_obj_set_style_text_color(lbl_title, lv_color_hex(COL_INK), 0);
+  lv_obj_set_style_text_font(lbl_title, &lv_font_montserrat_18, 0);
+  lv_obj_set_pos(lbl_title, UX(8), UY(6));
+
+  lbl_status = lv_label_create(scr);
+  lv_label_set_text(lbl_status, "waiting");
+  lv_obj_set_style_text_color(lbl_status, lv_color_hex(COL_WARN), 0);
+  lv_obj_set_style_text_font(lbl_status, &lv_font_montserrat_14, 0);
+  lv_obj_align(lbl_status, LV_ALIGN_TOP_RIGHT, UX(-8), UY(8));
+
+  lbl_host = lv_label_create(scr);
+  lv_label_set_text(lbl_host, "Connect USB + run host script");
+  lv_label_set_long_mode(lbl_host, LV_LABEL_LONG_DOT);
+  lv_obj_set_width(lbl_host, UI_HOR_RES - UW(16));
+  lv_obj_set_style_text_color(lbl_host, lv_color_hex(COL_MUTED), 0);
+  lv_obj_set_style_text_font(lbl_host, &lv_font_montserrat_14, 0);
+  lv_obj_set_pos(lbl_host, UX(8), UY(28));
+
+  lv_obj_t *line = lv_obj_create(scr);
+  lv_obj_set_size(line, UI_HOR_RES - UW(16), 1);
+  lv_obj_set_pos(line, UX(8), UY(48));
+  lv_obj_set_style_bg_color(line, lv_color_hex(COL_LINE), 0);
+  lv_obj_set_style_bg_opa(line, LV_OPA_COVER, 0);
+  lv_obj_set_style_border_width(line, 0, 0);
+  lv_obj_set_style_pad_all(line, 0, 0);
+  lv_obj_clear_flag(line, LV_OBJ_FLAG_SCROLLABLE);
+
+  row_cpu = make_row(scr, "CPU", 56);
+  row_gpu = make_row(scr, "GPU", 96);
+  row_ram = make_row(scr, "RAM", 136);
+  row_disk = make_row(scr, "DISK", 176);
+
+  last_paint_ms = 0;
+}
+
+static void paint() {
+  const HostInfo &h = host_info_get();
+  const bool live = host_info_is_live(5000);
+
+  if (lbl_status) {
+    if (!h.valid) {
+      lv_label_set_text(lbl_status, "waiting");
+      lv_obj_set_style_text_color(lbl_status, lv_color_hex(COL_WARN), 0);
+    } else if (live) {
+      lv_label_set_text(lbl_status, "live");
+      lv_obj_set_style_text_color(lbl_status, lv_color_hex(COL_OK), 0);
+    } else {
+      lv_label_set_text(lbl_status, "stale");
+      lv_obj_set_style_text_color(lbl_status, lv_color_hex(COL_BAD), 0);
+    }
+  }
+
+  if (!h.valid) {
+    return;
+  }
+
+  if (lbl_host) {
+    lv_label_set_text(lbl_host, h.host[0] ? h.host : "(unknown host)");
+  }
+
+  char buf[48];
+
+  int cpu_pct = (int)(h.cpu_pct + 0.5f);
+  snprintf(buf, sizeof(buf), "%d%%", cpu_pct);
+  set_row_pct(row_cpu, cpu_pct, h.cpu[0] ? h.cpu : "CPU", buf);
+
+  if (h.gpu_pct < 0) {
+    set_row_pct(row_gpu, 0, h.gpu[0] ? h.gpu : "GPU", "n/a");
+    if (row_gpu.lbl_pct) {
+      lv_obj_set_style_text_color(row_gpu.lbl_pct, lv_color_hex(COL_MUTED), 0);
+    }
+  } else {
+    int gpu_pct = (int)(h.gpu_pct + 0.5f);
+    snprintf(buf, sizeof(buf), "%d%%", gpu_pct);
+    set_row_pct(row_gpu, gpu_pct, h.gpu[0] ? h.gpu : "GPU", buf);
+  }
+
+  int ram_pct = pct_of(h.ram_used_gb, h.ram_total_gb);
+  snprintf(buf, sizeof(buf), "%.1f/%.0fG", (double)h.ram_used_gb,
+           (double)h.ram_total_gb);
+  set_row_pct(row_ram, ram_pct, "Memory", buf);
+
+  int disk_pct = pct_of(h.disk_used_gb, h.disk_total_gb);
+  snprintf(buf, sizeof(buf), "%.0f/%.0fG", (double)h.disk_used_gb,
+           (double)h.disk_total_gb);
+  set_row_pct(row_disk, disk_pct, "System drive", buf);
+}
+
+void ui_tick() {
+  const uint32_t now = millis();
+  if (now - last_paint_ms < 200) {
+    return;
+  }
+  last_paint_ms = now;
+  paint();
+}