Remote: match the old remote's hardware; old remote code in LEGACY

- LEGACY/remote/teensy/: old remote sketch from https://mangavalk.com/Hexapod/remote.git @ 492dece (reference only). - remote/Config.h: sticks on A0-A5, Nextion on Serial1 (0/1), as in the old sketch; MPU6050 moved to Wire2 (25/24) since A4/A5 are Wire's pins. - NextionUI: controls on a vscope-global "control" page added to the old HMI; keeps the old t1 status texts; the old page-1 b2 button (and serial 'U') enter Nextion upload passthrough, following the PC's baud. - Docs: NEXTION.md, remote README wiring, CLAUDE.md. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-01 15:29:21 +02:00
1 parent 935526eab5
commit a961fa721b
@@ -14,7 +14,7 @@
 constexpr float TX_HZ = 100.0f;

 // ---- Radio (nRF24L01) on SPI0: MOSI 11, MISO 12, SCK 13 ----
-// BENCH: placeholder CE/CSN pins - match your wiring.
+// CE/CSN as in the old remote sketch (LEGACY/remote/teensy/Nrf.h).
 constexpr uint8_t RADIO_CE_PIN  = 9;
 constexpr uint8_t RADIO_CSN_PIN = 10;
 // Auto-retransmit: (delay units of 250us, count). Kept short on purpose - a
@@ -31,9 +31,11 @@ constexpr uint32_t LINK_LOST_MS = 300;
 // Logical axis order used everywhere in the remote code.
 enum StickAxis : uint8_t { L_X = 0, L_Y, L_TWIST, R_X, R_Y, R_TWIST, NUM_AXES };

-// BENCH: placeholder pins. A4/A5 (18/19) are skipped because they're the I2C
-// pins the MPU6050 uses.
-constexpr uint8_t STICK_PINS[NUM_AXES] = { A0, A1, A2, A3, A6, A7 };
+// A0-A5 in a row, as wired for the old remote (LEGACY/remote/teensy/Joysticks.h).
+// A4/A5 are also Wire's SDA/SCL - that's why the MPU6050 is on Wire2 below.
+// BENCH: which physical axis is on which pin wasn't recoverable from the old
+// code; reorder these so each lands on the right logical axis ('p' dump).
+constexpr uint8_t STICK_PINS[NUM_AXES] = { A0, A1, A2, A3, A4, A5 };

 // Each logical axis must end up: X + = pushed RIGHT, Y + = pushed FORWARD
 // (away from you), TWIST + = rotated COUNTERCLOCKWISE seen from above.
@@ -67,7 +69,9 @@ constexpr float STICK_EXPO[NUM_AXES]     = { 0.25f, 0.25f, 0.30f, 0.20f, 0.20f,
 // One-pole low-pass on raw ADC counts (1 = no filtering). Pots are noisy.
 constexpr float STICK_FILTER_ALPHA = 0.5f;

-// ---- Remote IMU: MPU6050 on I2C (Wire: SDA 18, SCL 19) ----
+// ---- Remote IMU: MPU6050 on the second I2C bus (Wire2: SDA2 = 25, SCL2 = 24) ----
+// Not Wire (18/19): those pins are stick axes A4/A5.
+#define IMU_WIRE Wire2
 constexpr uint8_t IMU_ADDR = 0x68;   // 0x69 if AD0 is pulled high
 // Mounting remap: which chip axis (0=X,1=Y,2=Z) and sign gives each handset
 // axis. Handset frame: +X = away from you, +Y = your left, +Z = up.
@@ -103,11 +107,24 @@ constexpr uint32_t WALK_LINGER_MS = 250;
 // (post-deadzone, -1000..1000 scale), so the robot never arms mid-command.
 constexpr int16_t ARM_CENTER_TOLERANCE = 50;

-// ---- Nextion touchscreen on Serial2 (RX2 = pin 7, TX2 = pin 8) ----
-#define NEXTION_SERIAL Serial2
-// BENCH: Nextion ships at 9600. The HMI's Program.s must set `bauds=115200`
-// (see remote/NEXTION.md) or change this to match.
+// ---- Nextion touchscreen on Serial1 (RX1 = pin 0, TX1 = pin 1), as in the old remote ----
+#define NEXTION_SERIAL Serial1
+// BENCH: the old sketch used the ITEAD library, whose nexInit() talks at 9600
+// unless it was modified. This firmware expects 115200: add `bauds=115200`
+// to the HMI's Program.s (see remote/NEXTION.md) or set 9600 here.
 constexpr uint32_t NEXTION_BAUD             = 115200;
+// Controls live on this page (remote/NEXTION.md). Its components must have
+// vscope = global, so the firmware can update them whichever page is showing.
+#define NEXTION_CONTROL_PAGE "control"
+// The old HMI's link-status texts (pages 1 and 3, both named t1), also
+// vscope = global. BENCH: use your real page names (Nextion's default
+// names are page0..page5; only page 4 "uploadscreen" is known).
+constexpr const char* NEXTION_STATUS_TEXTS[] = { "page1.t1", "page3.t1" };
+// The old HMI's "upload" button: page 1, component id 5 (b2), sends the
+// standard touch event. It puts the remote into Nextion upload passthrough.
+constexpr uint8_t NEXTION_UPLOAD_BUTTON_PAGE = 1;
+constexpr uint8_t NEXTION_UPLOAD_BUTTON_ID   = 5;
+#define NEXTION_UPLOAD_PAGE "uploadscreen"
 constexpr uint32_t NEXTION_FULL_REFRESH_MS  = 2000;   // re-push everything periodically (self-heals after a display reset)
 constexpr uint32_t NEXTION_LINK_REFRESH_MS  = 250;    // link-quality text update rate
 constexpr uint32_t STATUS_MESSAGE_MS        = 2500;   // how long transient status messages stay up
@@ -1,14 +1,25 @@
 # Nextion HMI build guide

-> The owner's earlier 6-page HMI is in `LEGACY/remote/remote.HMI`. This
-> guide describes the minimal single page the current firmware expects.
-> To reuse the old HMI instead, `NextionUI` has to be changed to match
-> its component names.
+Start from your existing HMI (`LEGACY/remote/remote.HMI`, the servo
+monitor) and **add one page named `control`** with the components below.
+Your existing pages keep working:
+
+| Existing | What the firmware does with it |
+|----------|--------------------------------|
+| page 1 `t1`, page 3 `t1` | writes `connected` / `not connected`, as the old firmware did. Set both to **vscope = global**, and put their real names (`page1.t1`, …) in `NEXTION_STATUS_TEXTS` in `Config.h` |
+| page 1 `b2` (id 5) | **upload mode**: keep "Send Component ID" ticked on it. The remote shows `uploadscreen` and passes USB straight through to the display, so Nextion Editor can upload over the remote's USB port. Power-cycle to leave. Serial key `U` does the same |
+| page 4 `uploadscreen` | shown on entering upload mode |
+| page 3 sliders `h0`–`h17` | not driven yet: the robot doesn't send servo positions back (that needs the planned telemetry channel) |

 The firmware drives the display by **component name**, and the display
 talks back with small custom frames sent from each button's touch event.
-Build one page in Nextion Editor to match the tables below. Layout, fonts
-and colors are up to you. The names and event code must match exactly.
+Layout, fonts and colors are up to you. The names and event code must
+match exactly.
+
+**Set every component on `control` to vscope = global.** The firmware
+writes them as `control.<name>` and keeps them current whichever page is
+showing. A local component on another page can't be written from outside,
+and with `bkcmd=0` the display ignores those writes silently.

 The remote is authoritative. Use **plain Button** components (not
 Dual-state buttons) and don't toggle anything locally in the HMI. The
@@ -24,9 +35,13 @@ bauds=115200
 ```

 This sets the display to the `NEXTION_BAUD` in `remote/Config.h`. The
-display ships at 9600, and `bauds=` persists across power cycles.
+display ships at 9600, and `bauds=` persists across power cycles. The old
+firmware used the ITEAD library at 9600, so your HMI probably runs at 9600
+today.

-Name the page `main` (page 0). The firmware never changes pages.
+Name the new page `control`. The firmware never changes pages, except
+into `uploadscreen` for upload mode. Add buttons on your other pages to
+switch to it (`page control`).

 ## Components

@@ -75,8 +90,9 @@ uses **Touch Move** as well so the value tracks your finger). Frame format:
 | `bCal`    | `printh 23 01 43`                        | `C` start / save stick calibration |
 | `bCalX`   | `printh 23 01 51`                        | `Q` cancel calibration         |

-**Uncheck "Send Component ID"** on every component. The firmware ignores
-standard touch frames, and they only add serial traffic.
+**Uncheck "Send Component ID"** on every component on `control`: those
+standard touch frames only add serial traffic. The one exception is the old
+page 1 `b2` upload button (see the top).

 Protocol details and the parser live in `NextionUI.h/.cpp`. To add a
 control, pick an unused command byte, add it to `NextionUI::decodeCustom()`
@@ -7,21 +7,26 @@ static constexpr uint16_t COL_OFF    = 50712;   // Nextion default light gray
 static constexpr uint16_t COL_DANGER = 63488;   // red
 static constexpr uint16_t COL_WARN   = 64512;   // orange

-// Serial2's default 64-byte TX buffer would make a full redraw (~300 bytes
-// at 115200 baud) block the TX loop for ~25 ms. Give it room to queue.
+// The default 64-byte TX buffer would make a full redraw (~400 bytes at
+// 115200 baud) block the TX loop for ~35 ms. Give it room to queue.
 static uint8_t tx_extra[1024];
 static uint8_t rx_extra[128];

+// Every control lives on NEXTION_CONTROL_PAGE with vscope = global, so it's
+// addressed as page.component and can be updated whichever page is showing.
+#define P NEXTION_CONTROL_PAGE "."
+
 void NextionUI::begin() {
  NEXTION_SERIAL.begin(NEXTION_BAUD);
  NEXTION_SERIAL.addMemoryForWrite(tx_extra, sizeof(tx_extra));
  NEXTION_SERIAL.addMemoryForRead(rx_extra, sizeof(rx_extra));
-  cmd("bkcmd=0");   // no success/fail replies - we never need them
+  cmd("bkcmd=0");   // no success/fail replies - we never need them (and a
+                    // write to a page the HMI doesn't have is then just ignored)
  force_full_ = true;
 }

 void NextionUI::cmd(const char* fmt, ...) {
-  char buf[64];
+  char buf[80];
  va_list ap;
  va_start(ap, fmt);
  vsnprintf(buf, sizeof(buf), fmt, ap);
@@ -50,11 +55,31 @@ bool NextionUI::decodeCustom(UiEvent& out) {
    case 'Z': out.cmd = UiCmd::ZeroGyro;          break;
    case 'C': out.cmd = UiCmd::CalStartSave;      break;
    case 'Q': out.cmd = UiCmd::CalCancel;         break;
+    case 'U': out.cmd = UiCmd::NextionUpload;     break;
    default:  return false;
  }
  return true;
 }

+// Standard Nextion frames (terminated FF FF FF). Two matter:
+//   0x88 / 0x00         display (re)started -> redraw everything
+//   0x65 page id event  touch event from a component with "Send Component
+//                       ID" ticked - how the old HMI's upload button (b2)
+//                       reports, so it keeps working unchanged.
+bool NextionUI::decodeNative(UiEvent& out) {
+  if (native_buf_[0] == 0x88 || native_buf_[0] == 0x00) {
+    force_full_ = true;
+    return false;
+  }
+  if (native_buf_[0] == 0x65 && native_len_ >= 4 &&
+      native_buf_[1] == NEXTION_UPLOAD_BUTTON_PAGE && native_buf_[2] == NEXTION_UPLOAD_BUTTON_ID) {
+    out.cmd = UiCmd::NextionUpload;
+    out.value = 0;
+    return true;
+  }
+  return false;
+}
+
 bool NextionUI::poll(UiEvent& out) {
  while (NEXTION_SERIAL.available()) {
    uint8_t b = NEXTION_SERIAL.read();
@@ -64,7 +89,7 @@ bool NextionUI::poll(UiEvent& out) {
          rx_ = Rx::CustomLen;
        } else {
          rx_ = Rx::Native;
-          native_first_ = b;
+          native_buf_[0] = b;
          native_len_ = 1;
          ff_run_ = (b == 0xFF) ? 1 : 0;
        }
@@ -89,12 +114,12 @@ bool NextionUI::poll(UiEvent& out) {
        break;

      case Rx::Native:
+        if (native_len_ < sizeof(native_buf_)) native_buf_[native_len_] = b;
        native_len_++;
        ff_run_ = (b == 0xFF) ? ff_run_ + 1 : 0;
        if (ff_run_ == 3) {
-          // 0x88 = "Nextion ready" after power-on/reset, 0x00 = startup.
-          if (native_first_ == 0x88 || native_first_ == 0x00) force_full_ = true;
          rx_ = Rx::Idle;
+          if (decodeNative(out)) return true;
        } else if (native_len_ > 16) {
          rx_ = Rx::Idle;   // not a frame we understand
        }
@@ -109,37 +134,40 @@ bool NextionUI::poll(UiEvent& out) {
 void NextionUI::pushState(const UiView& v, bool full) {
  const UiView& s = shown_;
  if (full || v.armed != s.armed) {
-    cmd("bArm.txt=\"%s\"", v.armed ? "ARMED" : "DISARMED");
-    cmd("bArm.bco=%u", v.armed ? COL_DANGER : COL_OFF);
+    cmd(P "bArm.txt=\"%s\"", v.armed ? "ARMED" : "DISARMED");
+    cmd(P "bArm.bco=%u", v.armed ? COL_DANGER : COL_OFF);
  }
  if (full || v.stand != s.stand) {
-    cmd("bStand.txt=\"%s\"", v.stand ? "STAND" : "SIT");
-    cmd("bStand.bco=%u", v.stand ? COL_ON : COL_OFF);
+    cmd(P "bStand.txt=\"%s\"", v.stand ? "STAND" : "SIT");
+    cmd(P "bStand.bco=%u", v.stand ? COL_ON : COL_OFF);
  }
-  if (full || v.gait_wave != s.gait_wave)       cmd("bGait.txt=\"%s\"", v.gait_wave ? "WAVE" : "TRIPOD");
-  if (full || v.mode_b != s.mode_b)             cmd("bMode.txt=\"%s\"", v.mode_b ? "HEADING" : "DIRECT");
-  if (full || v.rstick_xlate != s.rstick_xlate) cmd("bRs.txt=\"%s\"", v.rstick_xlate ? "R: MOVE" : "R: ROTATE");
-  if (full || v.remote_gyro != s.remote_gyro)   cmd("bRGyro.bco=%u", v.remote_gyro ? COL_ON : COL_OFF);
-  if (full || v.robot_gyro != s.robot_gyro)     cmd("bBGyro.bco=%u", v.robot_gyro ? COL_ON : COL_OFF);
+  if (full || v.gait_wave != s.gait_wave)       cmd(P "bGait.txt=\"%s\"", v.gait_wave ? "WAVE" : "TRIPOD");
+  if (full || v.mode_b != s.mode_b)             cmd(P "bMode.txt=\"%s\"", v.mode_b ? "HEADING" : "DIRECT");
+  if (full || v.rstick_xlate != s.rstick_xlate) cmd(P "bRs.txt=\"%s\"", v.rstick_xlate ? "R: MOVE" : "R: ROTATE");
+  if (full || v.remote_gyro != s.remote_gyro)   cmd(P "bRGyro.bco=%u", v.remote_gyro ? COL_ON : COL_OFF);
+  if (full || v.robot_gyro != s.robot_gyro)     cmd(P "bBGyro.bco=%u", v.robot_gyro ? COL_ON : COL_OFF);
  if (full || v.speed_target != s.speed_target) {
-    cmd("hSpeed.val=%u", v.speed_target);
-    cmd("nSpeed.val=%u", (v.speed_target * 100 + 127) / 255);
+    cmd(P "hSpeed.val=%u", v.speed_target);
+    cmd(P "nSpeed.val=%u", (v.speed_target * 100 + 127) / 255);
  }
  if (full || v.height != s.height) {
-    cmd("hHeight.val=%d", v.height / 10 + 100);   // slider 0..200, 100 = default
-    cmd("nHeight.val=%d", v.height / 10);         // -100..100 %
+    cmd(P "hHeight.val=%d", v.height / 10 + 100);   // slider 0..200, 100 = default
+    cmd(P "nHeight.val=%d", v.height / 10);         // -100..100 %
  }
  if (full || v.calibrating != s.calibrating) {
-    cmd("bCal.txt=\"%s\"", v.calibrating ? "SAVE CAL" : "CAL");
-    cmd("bCal.bco=%u", v.calibrating ? COL_WARN : COL_OFF);
+    cmd(P "bCal.txt=\"%s\"", v.calibrating ? "SAVE CAL" : "CAL");
+    cmd(P "bCal.bco=%u", v.calibrating ? COL_WARN : COL_OFF);
  }
-  if (full || v.message != s.message) cmd("tMsg.txt=\"%s\"", v.message);
+  if (full || v.message != s.message) cmd(P "tMsg.txt=\"%s\"", v.message);
 }

 void NextionUI::pushLink(const UiView& v) {
-  if (v.link_ok) cmd("tLink.txt=\"LINK %u%%\"", v.link_pct);
-  else           cmd("tLink.txt=\"NO LINK\"");
-  cmd("tLink.pco=%u", v.link_ok ? COL_ON : COL_DANGER);
+  if (v.link_ok) cmd(P "tLink.txt=\"LINK %u%%\"", v.link_pct);
+  else           cmd(P "tLink.txt=\"NO LINK\"");
+  cmd(P "tLink.pco=%u", v.link_ok ? COL_ON : COL_DANGER);
+  // The old HMI's own status texts, same wording as the old firmware.
+  for (const char* t : NEXTION_STATUS_TEXTS)
+    cmd("%s.txt=\"%s\"", t, v.link_ok ? "connected" : "not connected");
 }

 void NextionUI::render(const UiView& v, uint32_t now_ms) {
@@ -160,3 +188,27 @@ void NextionUI::render(const UiView& v, uint32_t now_ms) {

  shown_ = v;
 }
+
+// ---- Upload passthrough ----
+
+// Lets Nextion Editor upload a new .tft through the remote's USB port, with
+// the display still in the case: show the upload page, then wire USB serial
+// straight through to the display, forever (power-cycle to leave). Nextion
+// Editor switches baud rate mid-upload; Teensy's USB serial reports the
+// rate the PC asked for, so the display side follows it.
+void NextionUI::runUploadPassthrough() {
+  cmd("page " NEXTION_UPLOAD_PAGE);
+  NEXTION_SERIAL.flush();
+  delay(100);
+  uint32_t baud = NEXTION_BAUD;
+  for (;;) {
+    uint32_t want = Serial.baud();
+    if (want >= 2400 && want != baud) {
+      NEXTION_SERIAL.flush();
+      NEXTION_SERIAL.begin(want);
+      baud = want;
+    }
+    while (Serial.available())         NEXTION_SERIAL.write(Serial.read());
+    while (NEXTION_SERIAL.available()) Serial.write(NEXTION_SERIAL.read());
+  }
+}
@@ -8,8 +8,9 @@
 //      '#' <len> <cmd> [value]        e.g. printh 23 01 41   (ToggleArm)
 //                                          printh 23 02 56 + prints hSpeed.val,1
 //    Command bytes are listed in NEXTION.md and in NextionUI.cpp.
-//    Native Nextion return frames (terminated FF FF FF) are also parsed so a
-//    display reset (0x88 "ready") triggers a full redraw.
+//    Native Nextion return frames (terminated FF FF FF) are also parsed: a
+//    display reset (0x88 "ready") triggers a full redraw, and the old HMI's
+//    upload button sends a standard touch event (0x65) that's recognized.
 //
 //  remote -> Nextion: plain instructions ("bArm.txt=\"ARMED\"" + FF FF FF).
 //
@@ -23,12 +24,16 @@ public:
  bool poll(UiEvent& out);                 // call every loop; returns one decoded event at a time
  void render(const UiView& v, uint32_t now_ms);

+  // Nextion Editor upload through the remote's USB port. Never returns.
+  [[noreturn]] void runUploadPassthrough();
+
 private:
  enum class Rx : uint8_t { Idle, CustomLen, CustomBody, Native };
  Rx rx_ = Rx::Idle;
  uint8_t body_[4];
  uint8_t body_len_ = 0, body_got_ = 0;
-  uint8_t native_first_ = 0, native_len_ = 0, ff_run_ = 0;
+  uint8_t native_buf_[8];
+  uint8_t native_len_ = 0, ff_run_ = 0;

  UiView shown_;
  bool force_full_ = true;
@@ -39,4 +44,5 @@ private:
  void pushState(const UiView& v, bool full);
  void pushLink(const UiView& v);
  bool decodeCustom(UiEvent& out);
+  bool decodeNative(UiEvent& out);
 };
@@ -11,17 +11,19 @@ at 100 Hz.
 From the repo root: `pio run -e remote`, flash with
 `pio run -e remote -t upload`, monitor with `pio device monitor -e remote`.

-## Wiring (placeholders; edit `Config.h` to match)
+## Wiring (from the old remote sketch in `LEGACY/remote/teensy/`; edit `Config.h` if yours differs)

 | Part | Signal | Teensy 4.1 pin |
 |------|--------|----------------|
 | nRF24L01 | MOSI / MISO / SCK | 11 / 12 / 13 (SPI0) |
 | nRF24L01 | CE / CSN | 9 / 10 |
 | nRF24L01 | VCC | 3.3 V, with a 10–100 µF cap right at the module |
-| MPU6050 | SDA / SCL | 18 / 19 (Wire) |
-| Nextion | TX → RX2, RX ← TX2 | 7 / 8 (Serial2), 5 V supply |
-| Left stick | X / Y / twist | A0 / A1 / A2 |
-| Right stick | X / Y / twist | A3 / A6 / A7 |
+| MPU6050 | SDA / SCL | **25 / 24 (Wire2)**: not 18/19, those are stick pins A4/A5 |
+| Nextion | TX → RX1, RX ← TX1 | 0 / 1 (Serial1), 5 V supply |
+| Sticks | 6 axes | A0–A5. Which axis is on which pin isn't known yet: reorder `STICK_PINS` until the `p` dump reads right |
+
+**MPU6050 rewiring:** the old remote had its MPU code switched off, probably
+because A4/A5 double as Wire's pins. Move the MPU's SDA/SCL to pins 25/24.

 Stick pots are wired 3.3 V – wiper – GND. **Never feed 5 V into a Teensy
 4.x analog pin.**
@@ -101,7 +103,7 @@ display attached.
 | `]` / `[` | height up / down 10% | | |
 | `c` | start / save calibration | `x` | cancel calibration |
 | `p` | print status (raw + mapped sticks, IMU, link, state, cal) | `d` | toggle 10 Hz packet dump |
-| `R` | reset stick cal to Config defaults | | |
+| `R` | reset stick cal to Config defaults | `U` | Nextion upload mode (USB ↔ display; power-cycle to leave) |

 ## Bench-check checklist

@@ -9,15 +9,15 @@ static constexpr uint8_t REG_PWR_MGMT_1   = 0x6B;
 static constexpr uint8_t REG_ACCEL_XOUT_H = 0x3B;

 static bool writeReg(uint8_t reg, uint8_t val) {
-  Wire.beginTransmission(IMU_ADDR);
-  Wire.write(reg);
-  Wire.write(val);
-  return Wire.endTransmission() == 0;
+  IMU_WIRE.beginTransmission(IMU_ADDR);
+  IMU_WIRE.write(reg);
+  IMU_WIRE.write(val);
+  return IMU_WIRE.endTransmission() == 0;
 }

 bool RemoteIMU::begin() {
-  Wire.begin();
-  Wire.setClock(400000);
+  IMU_WIRE.begin();
+  IMU_WIRE.setClock(400000);
  ok_ = writeReg(REG_PWR_MGMT_1, 0x00);   // wake out of sleep
  if (!ok_) return false;
  writeReg(REG_CONFIG, 0x03);             // 44 Hz DLPF: a handheld remote doesn't need more bandwidth
@@ -49,16 +49,16 @@ bool RemoteIMU::begin() {
 }

 bool RemoteIMU::readRaw(float a[3], float g[3]) {
-  Wire.beginTransmission(IMU_ADDR);
-  Wire.write(REG_ACCEL_XOUT_H);
-  if (Wire.endTransmission(false) != 0) return false;
-  Wire.requestFrom((int)IMU_ADDR, 14);
-  if (Wire.available() < 14) return false;
+  IMU_WIRE.beginTransmission(IMU_ADDR);
+  IMU_WIRE.write(REG_ACCEL_XOUT_H);
+  if (IMU_WIRE.endTransmission(false) != 0) return false;
+  IMU_WIRE.requestFrom((int)IMU_ADDR, 14);
+  if (IMU_WIRE.available() < 14) return false;

  int16_t raw[7];   // ax ay az temp gx gy gz, big-endian
  for (int k = 0; k < 7; k++) {
-    uint8_t hi = Wire.read();   // two statements: the order of calls inside one expression is unspecified
-    uint8_t lo = Wire.read();
+    uint8_t hi = IMU_WIRE.read();   // two statements: the order of calls inside one expression is unspecified
+    uint8_t lo = IMU_WIRE.read();
    raw[k] = (int16_t)((hi << 8) | lo);
  }

@@ -78,6 +78,9 @@ bool RemoteState::handle(const UiEvent& e, Sticks& stick_hw, RemoteIMU& imu, uin
      setMessage("Calibration saved", now);
      return true;

+    case UiCmd::NextionUpload:
+      return false;   // not operator state - remote.ino handles it
+
    case UiCmd::CalCancel:
      if (!calibrating_) return false;
      stick_hw.cancelCalibration();
@@ -22,6 +22,7 @@ bool SerialConsole::poll(UiEvent& ui, Local& local) {
      case 'z': ui.cmd = UiCmd::ZeroGyro;          return true;
      case 'c': ui.cmd = UiCmd::CalStartSave;      return true;
      case 'x': ui.cmd = UiCmd::CalCancel;         return true;
+      case 'U': ui.cmd = UiCmd::NextionUpload;     return true;
      case 'p': local = Local::PrintStatus;        return true;
      case 'd': local = Local::ToggleDump;         return true;
      case 'R': local = Local::ResetCal;           return true;
@@ -23,6 +23,7 @@ enum class UiCmd : uint8_t {
  ZeroGyro,            // capture the handset's current attitude as "level"
  CalStartSave,        // start sweep calibration, or save it if running
  CalCancel,
+  NextionUpload,       // USB <-> display passthrough for Nextion Editor (handled in remote.ino)
 };

 struct UiEvent {
@@ -47,12 +47,27 @@ static void dumpPacket(const CmdPacket& p) {
                p.remote_roll, p.remote_pitch, p.body_height, p.speed_scale, p.flags);
 }

+// Nextion Editor upload through this USB port (the old remote's b2 button).
+// Never returns: the TX loop stops, so the robot loses the link and
+// disarms itself after LINK_TIMEOUT_SEC. Power-cycle the remote to leave.
+static void enterNextionUpload() {
+  state.handle(UiEvent{ UiCmd::Disarm, 0 }, sticks, imu, millis());
+  Serial.println("Nextion upload mode: connect Nextion Editor to this USB port and upload.");
+  Serial.println("Power-cycle the remote to leave.");
+  Serial.flush();
+  nextion.runUploadPassthrough();
+}
+
 static void pollInputs(uint32_t now_ms) {
  UiEvent ev;
-  while (nextion.poll(ev)) state.handle(ev, sticks, imu, now_ms);
+  while (nextion.poll(ev)) {
+    if (ev.cmd == UiCmd::NextionUpload) enterNextionUpload();
+    state.handle(ev, sticks, imu, now_ms);
+  }

  SerialConsole::Local local;
  while (console.poll(ev, local)) {
+    if (ev.cmd == UiCmd::NextionUpload) enterNextionUpload();
    if (ev.cmd != UiCmd::None) {
      bool ok = state.handle(ev, sticks, imu, now_ms);
      if (!ok && state.message(now_ms)[0]) Serial.println(state.message(now_ms));