Wireless runtime (Wi-Fi and BLE)

Wi-Fi and BLE on the ESP32 share one radio, one PHY, the coexistence arbiter and one allocator. They are therefore brought up by one owner, rohi_net_esp::EspWireless, and not by two independent drivers. This page describes that runtime and how Wi-Fi and BLE interact; the portable APIs are in Networking and Control plane.

EspWireless::new(WIFI, BT, heap)     one owner of radio peripherals and the wireless heap
  ├── wifi(&mut NetResources)  ->  EspWifi + NetRunner + EspIp   (Wi-Fi control plane + IP data plane)
  └── ble(config, &mut BleResources) ->  EspBle + BleRunner      (BLE peripheral transport)

Bring-up

let heap = rohi_net_esp::wireless_heap!(WIRELESS_HEAP_SIZE);    // adds the single wireless heap
let mut wireless = EspWireless::new(peripherals.WIFI, peripherals.BT, heap);
esp_rtos::start(...);
let (wifi, net_runner, ip) = wireless.wifi(NET_RESOURCES.init(NetResources::new()))?;
let (ble, ble_runner) = wireless.ble(BLE_CONFIG, BLE_RESOURCES.init(Default::default()))?;

Rules:

• wireless_heap! and EspWireless::new are called once, before esp_rtos::start and before any radio use. The peripherals and the heap region are moved in, so a second call cannot compile.
• wifi() and ble() each hand out their driver once (WirelessError::AlreadyTaken / WifiError::DriverError otherwise) and need the esp-rtos scheduler to be running.
• Neither driver initializes radio state or an allocator on its own. Nothing else in the firmware may add heap regions for the radio.
• A Wi-Fi or BLE failure must never stop the sensors: the firmware logs the error and carries on without that radio.

The sizes — the heap, the IP stack sockets, TCP buffers and the BLE queues — are chosen by the firmware in one place, for Altruist Urban firmwares/altruist-urban/src/resources.rs, see Resource limits.

How Wi-Fi and BLE interact

• Shared heap. Both controllers allocate from the same fixed wireless heap; see Memory model. wireless_heap() reports the free bytes and, with the heap-stats feature, the minimum free bytes, which must be checked with both radios busy.
• Coexistence. esp-radio runs with the coex feature so the radio arbitrates between the two protocols. Bringing the radio up, and the first Wi-Fi association in particular, keeps the core busy long enough to overrun the microphone DMA ring, so the firmware starts the sensor tasks after the first Wi-Fi attempt (bounded wait).
• Independent control. The BLE control plane configures Wi-Fi through ControlServices; the Wi-Fi manager never depends on BLE and BLE never touches the radio driver of Wi-Fi.
• Independent failure. A BLE host error restarts advertising; a Wi-Fi failure backs off and retries. Neither stops the other or the sensors.

Hardware status

Coexistence behaviour (BLE connected while Wi-Fi scans or reconnects) and the minimum free heap with both radios busy are tracked in Hardware testing; they are not yet fully measured.