Sign ITS messages on the ESP32-C5 with vanetza-idf, over USB or BLE
obu-firmware is now a port of the colleague's standalone VRU station (microbu-esp32c5/firmware, kept beside this repository and gitignored): the vanetza-idf C-ITS stack with the TS 103 097 security entity, credentials in NVS, the station-link v1 protocol over the native USB port (frame type 0x10 in the existing 0xAA55 framing) and over a BLE GATT peripheral, and its ITS-G5 radio adapter. The phone still builds CAM and VAM; the board adds GeoNetworking/BTP and signs with the provisioned authorization ticket. The private key never leaves the board. Builds with ESP-IDF 6.0.2 only, which vanetza-idf pins for the radio's private driver ABI. The previous C firmware stays on disk unbuilt; a full-flash backup of the bench board is kept in firmware-backups/ (gitignored). Changed against the colleague's firmware, marked MicrOBU: in the sources: - Reception unchanged for the app. vanetza-idf drops what it cannot verify (unsigned traffic, every RSU), so each captured frame also goes through the previous gn_unwrap.c and reaches the phone as link opcode V2X_RX (0x85), whose body is the old SERIAL_MSG_V2X_RX payload. - Unsigned transmission still possible, with the previous geonet.c header; the phone chooses per message. - Console on UART0 (CH343 port); the native USB port carries only link frames. - BLE advertising pauses while the USB link is in use: BLE and ITS-G5 share one RF front end. - NVS 80 KB (app at 0x20000). At 24 KB, with Wi-Fi settings the previous firmware left behind, the BLE bond could not be stored and the phone had to pair on every connection. - Bench fixes: the radio queue is drained before the first PoTi (no RX and ~177 queue drops before); the station loop waited pdMS_TO_TICKS(5) = 0 ticks at 100 Hz and starved the idle task; the 2.4 KB RX capture buffer is off the Wi-Fi task stack; BLE notifications longer than the MTU are dropped instead of cut short, MTU 517; serial writes are skipped with no USB host. - Manual country policy and TX-power read-back from the previous radio setup; logs for BLE encryption changes and the number of stored bonds. Verified on the bench board (COM3) with the phone over USB and BLE: CAM and VAM, signed and unsigned, go out; reception of the sim car and the RSU's CAM/SPATEM/MAPEM continues; the board survives app restarts and reconnects. See docs/06-signed-its-vam-ble.md.
This commit is contained in:
Ashin Walpola
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// micrOBU firmware: the ESP32-C5 half of the VRU ITS-S on vanetza-idf.
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// One station task owns stack, security entity and radio; the serial reader task only
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// enqueues frames. Link messages: implementation/station-link/README.md.
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#include "link_protocol.hpp"
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#include "link_service.hpp"
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#include "board_controls.hpp"
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#include "simple_ble.hpp"
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#include "serial_link.hpp"
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#include "station.hpp"
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#if CONFIG_MICROBU_TEST_CHANNEL
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#include "test_channel.hpp"
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#endif
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#include <esp_log.h>
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#include <esp_task_wdt.h>
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#include <esp_timer.h>
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#include <nvs_flash.h>
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#include <freertos/FreeRTOS.h>
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#include <freertos/queue.h>
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#include <freertos/task.h>
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#include <algorithm>
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#include <cstdio>
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#include <new>
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namespace {
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const char* TAG = "microbu";
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/// @brief Represents one frame received from a transport, to be queued for the station task.
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struct Incoming {
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microbu::LinkTransport transport;
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microbu::serial::Frame frame;
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};
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QueueHandle_t frames = nullptr; // FIFO of Incoming* (8 bytes each); frame bytes never enter the queue itself
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/// @brief Attempts to heap-allocate an Incoming so it can be pushed onto the frames queue.
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/// @param transport Transport the frame arrived on.
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/// @param frame Decoded frame to take ownership of.
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/// @return Owning pointer to push onto the queue, or nullptr if allocation failed.
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Incoming* try_new_incoming(microbu::LinkTransport transport, microbu::serial::Frame frame) noexcept {
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try {
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// std::move here steals frame's payload buffer into the heap Incoming (no byte copy);
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// it has nothing to do with the queue below, which only ever transports the resulting pointer.
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return new Incoming {transport, std::move(frame)};
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} catch (const std::bad_alloc&) {
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return nullptr;
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}
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}
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/// @brief Dispatches one queued frame to the link service (or the test channel); logs and drops it on failure.
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void handle_incoming(microbu::Station& station, microbu::LinkService& link, const Incoming& incoming) {
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try {
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if (incoming.frame.type == microbu::serial::FrameType::LINK)
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link.handle(incoming.frame.payload, incoming.transport);
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#if CONFIG_MICROBU_TEST_CHANNEL
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else if (incoming.transport == microbu::LinkTransport::serial &&
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incoming.frame.type == microbu::serial::FrameType::TEST)
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microbu::serial::write(microbu::serial::FrameType::TEST,
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microbu::test_channel_execute(station, incoming.frame.payload));
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#endif
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} catch (const std::bad_alloc&) {
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ESP_LOGE(TAG, "out of memory while handling a frame");
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} catch (const std::exception& e) {
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ESP_LOGE(TAG, "frame handling failed: %s", e.what());
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}
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}
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/// @brief MicrOBU: BLE and ITS-G5 share the C5's one RF front end. While the phone is talking over
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/// USB there is no reason for BLE to take airtime, so advertising stops until the USB link has been
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/// quiet for CONFIG_MICROBU_BLE_USB_IDLE_MS. A phone already connected over BLE is left connected.
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void pause_ble_while_usb_in_use() {
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const auto last = microbu::serial::last_frame_ms();
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const auto now = static_cast<std::uint32_t>(esp_timer_get_time() / 1000);
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const bool usb_in_use = last != 0 && now - last < CONFIG_MICROBU_BLE_USB_IDLE_MS;
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microbu::ble::set_advertising_allowed(!usb_in_use);
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}
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/// @brief FreeRTOS task body: owns the station, link service and board controls. Drains the incoming queue.
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void station_task(void*) {
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microbu::Station station;
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microbu::LinkService link(station);
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microbu::BoardControls controls;
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station.on_disseminated([&controls] { controls.blink(); });
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station.on_received([&controls] { controls.blink(); });
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ESP_LOGI(TAG, "station task ready; the phone/PC configures the station over BLE or USB Serial-JTAG");
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for (;;) { /// main loop: drain the incoming queue, tick the station and link service, tick the controls
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Incoming* incoming = nullptr;
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// MicrOBU: at least one tick. At CONFIG_FREERTOS_HZ=100 pdMS_TO_TICKS(5) is 0, so the wait
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// never blocked: this priority-10 task spun on the single core, starved every lower-priority
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// task and the idle task (task watchdog), for as long as the board ran.
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if (xQueueReceive(frames, &incoming, std::max<TickType_t>(1, pdMS_TO_TICKS(5))) == pdTRUE && incoming) {
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handle_incoming(station, link, *incoming);
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delete incoming;
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}
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station.tick();
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link.tick();
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controls.tick();
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pause_ble_while_usb_in_use();
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}
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}
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}
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/// @brief Firmware entry point: initializes NVS, watchdog, serial/BLE transports, and starts the station task.
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extern "C" void app_main() {
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// NVS: the credential store (and the Wi-Fi driver's calibration data)
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esp_err_t nvs = nvs_flash_init();
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if (nvs == ESP_ERR_NVS_NO_FREE_PAGES || nvs == ESP_ERR_NVS_NEW_VERSION_FOUND) {
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ESP_ERROR_CHECK(nvs_flash_erase());
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nvs = nvs_flash_init();
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}
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ESP_ERROR_CHECK(nvs);
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// Signing and verification take tens of milliseconds each on the C5. This keeps the idle
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// watchdog from reporting a busy station task (5 s default) while a credential bundle applies.
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esp_task_wdt_config_t watchdog = {};
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watchdog.timeout_ms = 30000;
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watchdog.idle_core_mask = (1 << portNUM_PROCESSORS) - 1;
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watchdog.trigger_panic = false; // log, don't reboot, on timeout
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esp_task_wdt_reconfigure(&watchdog);
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frames = xQueueCreate(32, sizeof(Incoming*));
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microbu::serial::start([](microbu::serial::Frame frame) {
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auto* copy = try_new_incoming(microbu::LinkTransport::serial, std::move(frame));
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if (!copy) return;
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// xQueueSend copies the 8-byte pointer value into the queue, not *copy itself.
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// station_task then pops pointers FIFO and owns/deletes whatever it receives.
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if (xQueueSend(frames, ©, 0) != pdTRUE) delete copy; // the phone retries on a missing RESULT
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});
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if (!microbu::ble::start([](microbu::link::Bytes message) {
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microbu::serial::Frame frame {microbu::serial::FrameType::LINK, std::move(message)};
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auto* copy = try_new_incoming(microbu::LinkTransport::ble, std::move(frame));
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if (!copy) return;
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if (xQueueSend(frames, ©, 0) != pdTRUE) delete copy; // same hand-off as the serial callback above
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})) {
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ESP_LOGE(TAG, "BLE station link failed to start. USB remains available");
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}
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ESP_LOGI(TAG, "MicrOBU obu-firmware on vanetza-idf, station-link v1 + V2X_RX, console on UART0%s",
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#if CONFIG_MICROBU_TEST_CHANNEL
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", test channel enabled");
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#else
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"");
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#endif
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xTaskCreate(station_task, "station", 12288, nullptr, 10, nullptr);
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}
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