feat: Add v0.3 OTA updates — dual partition, esp-ota tool, rollback

Dual OTA partition table (ota_0/ota_1, 1920 KB each) on 4MB flash. Firmware gains OTA command, LED_OTA double-blink, version in STATUS, and automatic rollback validation. Pi-side esp-ota tool serves firmware via HTTP and orchestrates the update flow. esp-fleet gains ota subcommand.
2026-02-04 16:19:09 +01:00
parent 44bd549761
commit d65ac208b9
8 changed files with 368 additions and 36 deletions
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -8,25 +8,31 @@
 - [x] List firmware modification ideas with priorities
 - [x] Verify build from repo (ESP-IDF v5.5.2, aarch64)

-## v0.2 - Remote Management [IN PROGRESS]
+## v0.2 - Remote Management [DONE]
 - [x] Add UDP command listener on ESP32 (port 5501)
 - [x] Implement REBOOT command
 - [x] Implement IDENTIFY command (LED solid 5s)
- [x] Implement STATUS command (uptime, heap, RSSI, tx_power, rate)
+- [x] Implement STATUS command (uptime, heap, RSSI, tx_power, rate, version)
 - [x] Implement RATE command (change ping Hz, NVS persist)
 - [x] Implement POWER command (TX power dBm, NVS persist)
 - [x] Add LED status indicator (off/slow blink/fast blink/solid)
 - [x] NVS persistence for rate and tx_power settings
- [x] Pi-side `esp-cmd` CLI tool
- [ ] Build and flash test on device
- [ ] Update CHEATSHEET.md with new commands
+- [x] Pi-side `esp-cmd` and `esp-fleet` CLI tools
+- [x] mDNS hostname, watchdog, human-readable uptime
+- [x] Build and flash to device
+- [x] Update CHEATSHEET.md with new commands

-## v0.3 - OTA Updates
- [ ] Modify partition table for dual OTA
- [ ] Add OTA update handler in firmware
- [ ] HTTP firmware server on Pi
- [ ] Pi-side flash script (select device, push firmware)
- [ ] Rollback on failed update
+## v0.3 - OTA Updates [IN PROGRESS]
+- [x] Dual OTA partition table (ota_0 + ota_1, 1920 KB each)
+- [x] 4MB flash config, custom partitions in sdkconfig.defaults
+- [x] OTA command handler + ota_task in firmware
+- [x] LED_OTA double-blink pattern during download
+- [x] Bootloader rollback on failed update (30s watchdog)
+- [x] Version field in STATUS reply
+- [x] Pi-side `esp-ota` tool (HTTP server + OTA orchestration)
+- [x] `esp-fleet ota` subcommand (sequential fleet update)
+- [ ] USB-flash first device (partition table change)
+- [ ] End-to-end OTA test

 ## v0.4 - Adaptive Sampling
 - [ ] On-device wander calculation (simplified)
@@ -41,8 +47,8 @@
 - [ ] Pi-side BLE device tracking

 ## v1.0 - Production Firmware
- [ ] mDNS auto-discovery
- [ ] Watchdog + auto-recovery
+- [x] mDNS auto-discovery (done in v0.2)
+- [x] Watchdog + auto-recovery (done in v0.2)
 - [ ] On-device CSI processing (send metrics, not raw)
 - [ ] Configuration via UDP (WiFi SSID, target IP)
 - [ ] Comprehensive error handling
--- a/TASKS.md
+++ b/TASKS.md
@@ -2,30 +2,45 @@

 **Last Updated:** 2026-02-04

-## Current Sprint: v0.2 - Remote Management
+## Current Sprint: v0.3 - OTA Updates

 ### P0 - Critical
- [x] Firmware: UDP command listener (port 5501)
- [x] Firmware: LED status indicator (GPIO2)
- [x] Firmware: NVS config persistence (rate, tx_power)
- [~] Build and flash firmware to device
+- [x] Create dual OTA partition table (`partitions.csv`)
+- [x] Update `sdkconfig.defaults` (4MB flash, custom partitions, rollback, HTTP OTA)
+- [x] Firmware: OTA command, ota_task, LED_OTA, rollback validation
+- [x] Firmware: Add version to STATUS reply
+- [ ] `idf.py reconfigure` to regenerate sdkconfig
+- [ ] Build and USB-flash first device (partition table change requires USB)

 ### P1 - Important
- [x] Firmware: REBOOT, IDENTIFY, STATUS commands
- [x] Firmware: RATE command (10-100 Hz, restarts ping)
- [x] Firmware: POWER command (2-20 dBm)
- [x] Firmware: Refactor ping to support restart
- [x] Pi-side: `esp-cmd` CLI tool
- [ ] Update CHEATSHEET.md with esp-cmd usage
+- [x] Pi-side `esp-ota` tool (HTTP server + OTA orchestration)
+- [x] `esp-fleet ota` subcommand (sequential fleet OTA)
+- [ ] Test OTA end-to-end: `esp-ota amber-maple.local`
+- [ ] Regenerate `sdkconfig.sample`

 ### P2 - Normal
- [ ] Document esp-cmd in USAGE.md
- [ ] Add Kconfig CSI_CMD_PORT option
+- [ ] OTA update remaining fleet (muddy-storm, hollow-acorn) via USB
+- [ ] Test rollback (flash bad firmware, verify auto-revert)
+- [ ] Document esp-ota in USAGE.md

 ### P3 - Low
 - [ ] Document esp-crab dual-antenna capabilities
 - [ ] Document esp-radar console features

+## Completed: v0.2 - Remote Management
+
+- [x] Firmware: UDP command listener (port 5501)
+- [x] Firmware: LED status indicator (GPIO2)
+- [x] Firmware: NVS config persistence (rate, tx_power)
+- [x] Firmware: REBOOT, IDENTIFY, STATUS commands
+- [x] Firmware: RATE command (10-100 Hz, restarts ping)
+- [x] Firmware: POWER command (2-20 dBm)
+- [x] Pi-side: `esp-cmd` CLI tool
+- [x] Pi-side: `esp-fleet` fleet management tool
+- [x] mDNS hostname, watchdog, human-readable uptime
+- [x] Build and flash to device
+- [x] Update CHEATSHEET.md
+
 ## Completed: v0.1 - Documentation

 - [x] Copy firmware sources to project
@@ -34,12 +49,11 @@
 - [x] Create .gitignore for build artifacts
 - [x] Test building firmware from this repo
 - [x] Document CSI config options
- [x] Compare csi_recv vs csi_recv_router differences

 ## Notes

- Build confirmed working on ESP-IDF v5.5.2 (aarch64/Pi 5)
- v0.2 firmware adds ~1.5 KB heap + 6 KB stack usage
- NVS namespace: `csi_config` (keys: `send_rate`, `tx_power`)
- LED uses GPIO2 (built-in on most ESP32 dev boards)
- Command port default: 5501 (configurable via menuconfig)
+- NVS offset changes with new partition table — first USB flash resets saved config
+- First device must be USB-flashed to switch partition table, subsequent updates via OTA
+- `esp_https_ota` is built into ESP-IDF core — no extra deps needed
+- OTA download ~790 KB on LAN takes ~3-5s, well under 30s watchdog
+- CSI data keeps flowing during OTA download
--- a/docs/CHEATSHEET.md
+++ b/docs/CHEATSHEET.md
@@ -34,10 +34,11 @@ idf.py reconfigure                      # Re-fetch managed components
 ## Remote Management (esp-cmd)

 ```bash
-esp-cmd <host> STATUS                   # Uptime, heap, RSSI, tx_power, rate
+esp-cmd <host> STATUS                   # Uptime, heap, RSSI, tx_power, rate, version
 esp-cmd <host> IDENTIFY                 # LED solid 5s (find the device)
 esp-cmd <host> RATE 50                  # Set ping rate to 50 Hz (NVS saved)
 esp-cmd <host> POWER 15                 # Set TX power to 15 dBm (NVS saved)
+esp-cmd <host> OTA http://pi:8070/fw    # Trigger OTA update (use esp-ota instead)
 esp-cmd <host> REBOOT                   # Restart device
 ```

@@ -55,8 +56,34 @@ esp-fleet status                        # Query all sensors at once
 esp-fleet identify                      # Blink all LEDs
 esp-fleet rate 50                       # Set rate on all devices
 esp-fleet reboot                        # Reboot entire fleet
+esp-fleet ota                           # OTA update all (sequential)
+esp-fleet ota /path/to/firmware.bin     # OTA with custom firmware
 ```

+## OTA Updates (esp-ota)
+
+```bash
+esp-ota amber-maple.local               # OTA with default build
+esp-ota amber-maple.local -f fw.bin     # OTA with custom firmware
+esp-ota amber-maple.local --no-wait     # Fire and forget
+```
+
+**First flash after enabling OTA requires USB** (partition table change).
+After that, all updates are OTA.
+
+### OTA Flow
+
+1. Verifies device is alive via STATUS
+2. Starts temp HTTP server on Pi (port 8070)
+3. Sends `OTA http://<pi>:8070/<fw>.bin` via UDP
+4. Device downloads, flashes, reboots
+5. Verifies device responds post-reboot
+
+### Rollback
+
+If new firmware crashes or hangs, the 30s watchdog reboots and bootloader
+automatically rolls back to the previous firmware.
+
 ### LED States

 | LED | Meaning |
@@ -65,6 +92,7 @@ esp-fleet reboot                        # Reboot entire fleet
 | Slow blink (1 Hz) | Connected, no CSI activity |
 | Fast blink (5 Hz) | CSI data flowing |
 | Solid (5s) | IDENTIFY command active |
+| Double blink | OTA in progress |

 ## Test CSI Reception

@@ -109,6 +137,7 @@ secondary_channel,timestamp,ant,sig_len,rx_state,len,first_word,"[I,Q,...]"
 | `get-started/csi_recv_router/main/app_main.c` | Main firmware source |
 | `get-started/csi_recv_router/main/Kconfig.projbuild` | UDP/cmd port config |
 | `tools/esp-cmd` | Pi-side management CLI |
+| `tools/esp-ota` | Pi-side OTA update tool |
 | `tools/esp-fleet` | Fleet-wide command tool |
 | `get-started/csi_recv_router/sdkconfig.defaults` | SDK defaults |
 | `get-started/csi_recv_router/main/idf_component.yml` | Dependencies |
--- a/get-started/csi_recv_router/main/app_main.c
+++ b/get-started/csi_recv_router/main/app_main.c
@@ -30,6 +30,9 @@
 #include "esp_now.h"
 #include "esp_timer.h"
 #include "esp_task_wdt.h"
+#include "esp_ota_ops.h"
+#include "esp_https_ota.h"
+#include "esp_http_client.h"
 #include "driver/gpio.h"
 #include "mdns.h"

@@ -65,6 +68,7 @@ typedef enum {
    LED_SLOW_BLINK,
    LED_FAST_BLINK,
    LED_SOLID,
+    LED_OTA,
 } led_mode_t;

 /* --- Globals --- */
@@ -74,6 +78,7 @@ static esp_ping_handle_t s_ping_handle = NULL;
 static volatile led_mode_t s_led_mode = LED_OFF;
 static volatile int64_t s_last_csi_time = 0;
 static volatile int64_t s_identify_end_time = 0;
+static volatile bool s_ota_in_progress = false;

 /* UDP socket for CSI data transmission */
 static int s_udp_socket = -1;
@@ -181,6 +186,18 @@ static void led_task(void *arg)
            led_on = true;
            vTaskDelay(pdMS_TO_TICKS(200));
            break;
+        case LED_OTA:
+            /* Double-blink: on-off-on-off-pause */
+            gpio_set_level(LED_GPIO, 1);
+            vTaskDelay(pdMS_TO_TICKS(80));
+            gpio_set_level(LED_GPIO, 0);
+            vTaskDelay(pdMS_TO_TICKS(80));
+            gpio_set_level(LED_GPIO, 1);
+            vTaskDelay(pdMS_TO_TICKS(80));
+            gpio_set_level(LED_GPIO, 0);
+            vTaskDelay(pdMS_TO_TICKS(500));
+            led_on = false;
+            break;
        }
    }
 }
@@ -375,6 +392,41 @@ static esp_err_t wifi_ping_router_start(void)
    return ESP_OK;
 }

+/* --- OTA --- */
+
+static void ota_task(void *arg)
+{
+    char *url = (char *)arg;
+    ESP_LOGI(TAG, "OTA: downloading from %s", url);
+
+    s_led_mode = LED_OTA;
+
+    esp_http_client_config_t http_cfg = {
+        .url = url,
+        .timeout_ms = 30000,
+    };
+
+    esp_https_ota_config_t ota_cfg = {
+        .http_config = &http_cfg,
+    };
+
+    esp_err_t err = esp_https_ota(&ota_cfg);
+    free(url);
+
+    if (err == ESP_OK) {
+        ESP_LOGI(TAG, "OTA: success, rebooting...");
+        s_led_mode = LED_SOLID;
+        vTaskDelay(pdMS_TO_TICKS(500));
+        esp_restart();
+    } else {
+        ESP_LOGE(TAG, "OTA: failed: %s", esp_err_to_name(err));
+        s_led_mode = LED_SLOW_BLINK;
+        s_ota_in_progress = false;
+    }
+
+    vTaskDelete(NULL);
+}
+
 /* --- Command handler --- */

 static void reboot_after_delay(void *arg)
@@ -414,6 +466,8 @@ static int cmd_handle(const char *cmd, char *reply, size_t reply_size)
            rssi = ap.rssi;
        }

+        const esp_app_desc_t *app_desc = esp_app_get_description();
+
        char uptime_str[32];
        if (days > 0) {
            snprintf(uptime_str, sizeof(uptime_str), "%dd%dh%dm", days, hours, mins);
@@ -424,9 +478,9 @@ static int cmd_handle(const char *cmd, char *reply, size_t reply_size)
        }

        snprintf(reply, reply_size,
-                 "OK STATUS uptime=%s heap=%lu rssi=%d tx_power=%d rate=%d hostname=%s",
+                 "OK STATUS uptime=%s heap=%lu rssi=%d tx_power=%d rate=%d hostname=%s version=%s",
                 uptime_str, (unsigned long)heap, rssi, (int)s_tx_power_dbm,
-                 s_send_frequency, CONFIG_CSI_HOSTNAME);
+                 s_send_frequency, CONFIG_CSI_HOSTNAME, app_desc->version);
        return strlen(reply);
    }

@@ -458,6 +512,28 @@ static int cmd_handle(const char *cmd, char *reply, size_t reply_size)
        return strlen(reply);
    }

+    /* OTA <url> */
+    if (strncmp(cmd, "OTA ", 4) == 0) {
+        const char *url = cmd + 4;
+        if (strncmp(url, "http://", 7) != 0) {
+            snprintf(reply, reply_size, "ERR OTA url must start with http://");
+            return strlen(reply);
+        }
+        if (s_ota_in_progress) {
+            snprintf(reply, reply_size, "ERR OTA already in progress");
+            return strlen(reply);
+        }
+        char *url_copy = strdup(url);
+        if (!url_copy) {
+            snprintf(reply, reply_size, "ERR OTA out of memory");
+            return strlen(reply);
+        }
+        s_ota_in_progress = true;
+        xTaskCreate(ota_task, "ota_task", 8192, url_copy, 5, NULL);
+        snprintf(reply, reply_size, "OK OTA started");
+        return strlen(reply);
+    }
+
    snprintf(reply, reply_size, "ERR UNKNOWN");
    return strlen(reply);
 }
@@ -563,4 +639,14 @@ void app_main()
    wifi_ping_router_start();

    xTaskCreate(cmd_task, "cmd_task", 4096, NULL, 5, NULL);
+
+    /* OTA rollback: mark firmware valid if we got this far */
+    const esp_partition_t *running = esp_ota_get_running_partition();
+    esp_ota_img_states_t ota_state;
+    if (esp_ota_get_state_partition(running, &ota_state) == ESP_OK) {
+        if (ota_state == ESP_OTA_IMG_PENDING_VERIFY) {
+            ESP_LOGI(TAG, "OTA: marking firmware valid (rollback cancelled)");
+            esp_ota_mark_app_valid_cancel_rollback();
+        }
+    }
 }
--- a/get-started/csi_recv_router/partitions.csv
+++ b/get-started/csi_recv_router/partitions.csv
@@ -0,0 +1,6 @@
+# Name,   Type, SubType, Offset,   Size
+nvs,      data, nvs,     0x9000,   0x4000
+otadata,  data, ota,     0xd000,   0x2000
+phy_init, data, phy,     0xf000,   0x1000
+ota_0,    app,  ota_0,   0x10000,  0x1E0000
+ota_1,    app,  ota_1,   0x1F0000, 0x1E0000
--- a/get-started/csi_recv_router/sdkconfig.defaults
+++ b/get-started/csi_recv_router/sdkconfig.defaults
@@ -49,3 +49,16 @@ CONFIG_ESP32_WIFI_DYNAMIC_TX_BUFFER_NUM=32
 #
 CONFIG_ESP32S3_DEFAULT_CPU_FREQ_240=y
 CONFIG_ESP32S3_DEFAULT_CPU_FREQ_MHZ=240
+
+#
+# Flash & Partitions (4MB flash, dual OTA)
+#
+CONFIG_ESPTOOLPY_FLASHSIZE_4MB=y
+CONFIG_PARTITION_TABLE_CUSTOM=y
+CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions.csv"
+
+#
+# OTA Updates
+#
+CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE=y
+CONFIG_ESP_HTTPS_OTA_ALLOW_HTTP=y
--- a/tools/esp-fleet
+++ b/tools/esp-fleet
@@ -2,7 +2,9 @@
 """Query all ESP32 CSI sensors in parallel."""

 import concurrent.futures
+import os
 import socket
+import subprocess
 import sys

 DEFAULT_PORT = 5501
@@ -14,6 +16,8 @@ SENSORS = [
    ("hollow-acorn", "hollow-acorn.local"),
 ]

+ESP_OTA = os.path.join(os.path.dirname(os.path.abspath(__file__)), "esp-ota")
+
 USAGE = """\
 Usage: esp-fleet <command> [args...]

@@ -25,11 +29,14 @@ Commands:
  rate <10-100>       Set ping rate on all devices
  power <2-20>        Set TX power on all devices
  reboot              Reboot all devices
+  ota [firmware.bin]   OTA update all devices (sequentially)

 Examples:
  esp-fleet status
  esp-fleet identify
-  esp-fleet rate 50"""
+  esp-fleet rate 50
+  esp-fleet ota
+  esp-fleet ota /path/to/firmware.bin"""


 def query(name, host, cmd):
@@ -54,11 +61,33 @@ def query(name, host, cmd):
        sock.close()


+def run_ota(firmware=None):
+    """Run OTA on each sensor sequentially."""
+    for name, host in SENSORS:
+        print(f"\n{'='*40}")
+        print(f"OTA: {name} ({host})")
+        print(f"{'='*40}")
+        cmd = [ESP_OTA, host]
+        if firmware:
+            cmd += ["-f", firmware]
+        result = subprocess.run(cmd)
+        if result.returncode != 0:
+            print(f"ERR: OTA failed for {name}, stopping fleet OTA", file=sys.stderr)
+            sys.exit(1)
+    print(f"\nAll {len(SENSORS)} devices updated.")
+
+
 def main():
    if len(sys.argv) < 2 or sys.argv[1] in ("-h", "--help"):
        print(USAGE)
        sys.exit(0 if sys.argv[1:] and sys.argv[1] in ("-h", "--help") else 2)

+    # Handle OTA subcommand separately (sequential, not parallel)
+    if sys.argv[1].lower() == "ota":
+        firmware = sys.argv[2] if len(sys.argv) > 2 else None
+        run_ota(firmware)
+        return
+
    cmd = " ".join(sys.argv[1:]).strip().upper()

    with concurrent.futures.ThreadPoolExecutor(max_workers=len(SENSORS)) as pool:
--- a/tools/esp-ota
+++ b/tools/esp-ota
@@ -0,0 +1,149 @@
+#!/usr/bin/env python3
+"""OTA firmware update for ESP32 CSI devices."""
+
+import argparse
+import http.server
+import os
+import socket
+import sys
+import threading
+import time
+
+DEFAULT_CMD_PORT = 5501
+DEFAULT_HTTP_PORT = 8070
+DEFAULT_FW = os.path.expanduser(
+    "~/git/esp32-hacking/get-started/csi_recv_router/build/csi_recv_router.bin"
+)
+TIMEOUT = 2.0
+REBOOT_WAIT = 25.0
+STATUS_RETRIES = 10
+STATUS_INTERVAL = 3.0
+
+
+def resolve(host: str) -> str:
+    """Resolve hostname to IP address."""
+    try:
+        result = socket.getaddrinfo(host, DEFAULT_CMD_PORT, socket.AF_INET, socket.SOCK_DGRAM)
+        return result[0][4][0]
+    except socket.gaierror as e:
+        print(f"ERR: cannot resolve {host}: {e}", file=sys.stderr)
+        sys.exit(1)
+
+
+def udp_cmd(ip: str, cmd: str, timeout: float = TIMEOUT) -> str:
+    """Send UDP command and return reply."""
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    sock.settimeout(timeout)
+    try:
+        sock.sendto(cmd.encode(), (ip, DEFAULT_CMD_PORT))
+        data, _ = sock.recvfrom(512)
+        return data.decode().strip()
+    finally:
+        sock.close()
+
+
+def get_local_ip(target_ip: str) -> str:
+    """Determine which local IP the target can reach us on."""
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    try:
+        sock.connect((target_ip, 80))
+        return sock.getsockname()[0]
+    finally:
+        sock.close()
+
+
+def serve_firmware(directory: str, port: int) -> http.server.HTTPServer:
+    """Start HTTP server serving firmware directory in a background thread."""
+    handler = lambda *a, **k: http.server.SimpleHTTPRequestHandler(
+        *a, directory=directory, **k
+    )
+    server = http.server.HTTPServer(("0.0.0.0", port), handler)
+    thread = threading.Thread(target=server.serve_forever, daemon=True)
+    thread.start()
+    return server
+
+
+def main():
+    parser = argparse.ArgumentParser(description="OTA firmware update for ESP32 CSI devices")
+    parser.add_argument("host", help="Device hostname or IP (e.g., amber-maple.local)")
+    parser.add_argument("-f", "--firmware", default=DEFAULT_FW, help="Path to firmware .bin")
+    parser.add_argument("-p", "--port", type=int, default=DEFAULT_HTTP_PORT, help="HTTP server port")
+    parser.add_argument("--no-wait", action="store_true", help="Don't wait for reboot verification")
+    args = parser.parse_args()
+
+    fw_path = os.path.abspath(args.firmware)
+    if not os.path.isfile(fw_path):
+        print(f"ERR: firmware not found: {fw_path}", file=sys.stderr)
+        sys.exit(1)
+
+    fw_size = os.path.getsize(fw_path)
+    fw_dir = os.path.dirname(fw_path)
+    fw_name = os.path.basename(fw_path)
+
+    print(f"Firmware: {fw_path} ({fw_size // 1024} KB)")
+
+    # Resolve device
+    ip = resolve(args.host)
+    print(f"Device:   {args.host} ({ip})")
+
+    # Check device is alive
+    try:
+        reply = udp_cmd(ip, "STATUS")
+        print(f"Status:   {reply}")
+    except (socket.timeout, OSError) as e:
+        print(f"ERR: device not responding: {e}", file=sys.stderr)
+        sys.exit(1)
+
+    # Determine local IP
+    local_ip = get_local_ip(ip)
+    ota_url = f"http://{local_ip}:{args.port}/{fw_name}"
+    print(f"OTA URL:  {ota_url}")
+
+    # Start HTTP server
+    server = serve_firmware(fw_dir, args.port)
+    print(f"HTTP server on port {args.port}")
+
+    # Send OTA command
+    try:
+        reply = udp_cmd(ip, f"OTA {ota_url}")
+        print(f"OTA cmd:  {reply}")
+    except (socket.timeout, OSError) as e:
+        server.shutdown()
+        print(f"ERR: OTA command failed: {e}", file=sys.stderr)
+        sys.exit(1)
+
+    if not reply.startswith("OK"):
+        server.shutdown()
+        print(f"ERR: device rejected OTA: {reply}", file=sys.stderr)
+        sys.exit(1)
+
+    if args.no_wait:
+        print("OTA started (--no-wait, not verifying)")
+        # Keep server alive briefly for download
+        time.sleep(30)
+        server.shutdown()
+        return
+
+    # Wait for device to download, flash, and reboot
+    print(f"Waiting for reboot...")
+    time.sleep(REBOOT_WAIT)
+
+    # Verify device comes back
+    for attempt in range(1, STATUS_RETRIES + 1):
+        try:
+            ip = resolve(args.host)
+            reply = udp_cmd(ip, "STATUS", timeout=3.0)
+            print(f"Verified: {reply}")
+            server.shutdown()
+            return
+        except (socket.timeout, OSError):
+            print(f"  retry {attempt}/{STATUS_RETRIES}...")
+            time.sleep(STATUS_INTERVAL)
+
+    server.shutdown()
+    print("ERR: device did not come back after OTA", file=sys.stderr)
+    sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()