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_bleio HCI: fix advertising and ATT responses on ESP32-C6 AirLift controllers #11432

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_bleio HCI: fix advertising and ATT responses on ESP32-C6 AirLift controllers #11432

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a8bb681
_bleio HCI: use extended advertising commands on 5.x controllers
dhalbert Sep 21, 2026
1af5d49
_bleio HCI: send ACL data with the non-flushable start PB flag
dhalbert Sep 21, 2026
fd039bd
_bleio HCI: explain the extended advertising enable duration values
dhalbert Sep 21, 2026
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100 changes: 60 additions & 40 deletions devices/ble_hci/common-hal/_bleio/Adapter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,13 @@ static void check_enabled(bleio_adapter_obj_t *adapter) {
}
}

// A controller that supports extended advertising refuses legacy advertising
// commands (Command Disallowed) once any extended command has been sent, so
// use the extended command set exclusively on such controllers.
static bool adapter_uses_extended_advertising(bleio_adapter_obj_t *adapter) {
return BT_FEAT_LE_EXT_ADV(adapter->features);
}

// static bool adapter_on_ble_evt(ble_evt_t *ble_evt, void *self_in) {
// bleio_adapter_obj_t *self = (bleio_adapter_obj_t*)self_in;

Expand Down Expand Up @@ -296,17 +303,6 @@ static void bleio_adapter_hci_init(bleio_adapter_obj_t *self) {
self->max_acl_buffer_len = acl_max_len;
self->max_acl_num_buffers = acl_max_num;
}

// Get max advertising length if extended advertising is supported.
if (BT_FEAT_LE_EXT_ADV(self->features)) {
uint16_t max_adv_data_len;
if (hci_le_read_maximum_advertising_data_length(&max_adv_data_len) != HCI_OK) {
mp_raise_bleio_BluetoothError(MP_ERROR_TEXT("Could not get max advertising length"));
}
self->max_adv_data_len = max_adv_data_len;
} else {
self->max_adv_data_len = MAX_ADVERTISEMENT_SIZE;
}
}

void common_hal_bleio_adapter_construct_hci_uart(bleio_adapter_obj_t *self, busio_uart_obj_t *uart, digitalio_digitalinout_obj_t *rts, digitalio_digitalinout_obj_t *cts) {
Expand Down Expand Up @@ -343,7 +339,6 @@ void common_hal_bleio_adapter_set_enabled(bleio_adapter_obj_t *self, bool enable
// Enabling or disabling: stop any current activity; reset to known state.
hci_reset();
self->now_advertising = false;
self->extended_advertising = false;
self->circuitpython_advertising = false;
self->advertising_timeout_msecs = 0;

Expand Down Expand Up @@ -633,19 +628,17 @@ uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,
memcpy(&peer_addr.a.val, directed_to->bytes, sizeof(peer_addr.a.val));
}

bool extended =
advertising_data_len > self->max_adv_data_len || scan_response_data_len > self->max_adv_data_len;

if (extended) {
if (!BT_FEAT_LE_EXT_ADV(self->features)) {
mp_raise_bleio_BluetoothError(MP_ERROR_TEXT("Data length needs extended advertising, but this adapter does not support it"));
}

uint16_t props = 0;
if (adapter_uses_extended_advertising(self)) {
// Use legacy PDUs (ADV_IND etc.) so that 4.x centrals still see us and the
// 31-byte data limit applies unchanged; only the HCI command set is extended.
uint16_t props = BT_HCI_LE_ADV_PROP_LEGACY;
if (connectable) {
props |= BT_HCI_LE_ADV_PROP_CONN;
}
if (scan_response_data_len > 0) {
if (directed_to) {
props |= BT_HCI_LE_ADV_PROP_CONN | BT_HCI_LE_ADV_PROP_DIRECT;
} else {
props |= BT_HCI_LE_ADV_PROP_CONN | BT_HCI_LE_ADV_PROP_SCAN;
}
} else if (scan_response_data_len > 0) {
props |= BT_HCI_LE_ADV_PROP_SCAN;
}

Expand All @@ -660,21 +653,44 @@ uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,
interval_units, // max interval
0b111, // channel map: channels 37, 38, 39
anonymous ? BT_ADDR_LE_RANDOM : BT_ADDR_LE_PUBLIC,
&peer_addr, // peer_addr,
&peer_addr,
0x00, // filter policy: no filter
DEFAULT_TX_POWER,
BT_HCI_LE_EXT_SCAN_PHY_1M, // Secondary PHY to use
0x00, // AUX_ADV_IND shall be sent prior to next adv event
BT_HCI_LE_EXT_SCAN_PHY_1M, // Secondary PHY to use
0x00, // Advertising SID
0x00 // Scan req notify disable
BT_HCI_LE_ADV_TX_POWER_NO_PREF,
BT_HCI_LE_EXT_SCAN_PHY_1M, // primary PHY
0x00, // secondary max skip (unused with legacy PDUs)
BT_HCI_LE_EXT_SCAN_PHY_1M, // secondary PHY (unused with legacy PDUs)
0x00, // advertising SID
0x00 // scan request notification disabled
));

// We can use the duration mechanism provided, instead of our own.
self->advertising_timeout_msecs = 0;
hci_check_error(
hci_le_set_extended_advertising_data(
0, // handle
BT_HCI_LE_EXT_ADV_OP_COMPLETE_DATA,
BT_HCI_LE_EXT_ADV_FRAG_DISABLED,
advertising_data_len,
(uint8_t *)advertising_data));

// A scannable set must have scan response data defined before it is enabled,
// even if that data is empty.
if (props & BT_HCI_LE_ADV_PROP_SCAN) {
hci_check_error(
hci_le_set_extended_scan_response_data(
0, // handle
BT_HCI_LE_EXT_ADV_OP_COMPLETE_DATA,
BT_HCI_LE_EXT_ADV_FRAG_DISABLED,
scan_response_data_len,
(uint8_t *)scan_response_data));
}

// Use our own timeout rather than the controller's duration, so that we don't
// depend on receiving the LE Advertising Set Terminated event.
self->advertising_timeout_msecs = timeout * 1000;
self->advertising_start_ticks = supervisor_ticks_ms64();

// Duration 0 and max events 0 mean "advertise until disabled by the host".
uint8_t handle[1] = { 0 };
uint16_t duration_10msec[1] = { timeout * 100 };
uint16_t duration_10msec[1] = { 0 };

@tannewt tannewt Sep 21, 2026

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Why remove this?

@dhalbert dhalbert Sep 21, 2026

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Claude wrote this and then I rewrote it for clarity:

There are two ways to end a timed extended advertisement.

  • A. The controller does it. The host gives LE Set Extended Advertising Enable a nonzero duration and the controller reports the timeout expiry with the LE Advertising Set Terminated event.
  • B. The host does it, by passing duration 0 (which means "advertise until the host disables it", Vol 4 Part E §7.8.56) and calling the disable command itself when its own timer expires.

This PR uses B, the same one the legacy path already uses via advertising_timeout_msecs, so both paths share one mechanism. A needs the LE event mask extended to include the terminated event, and needs a handler for subevent 0x12. Without those the adapter never learns that advertising stopped and adapter.advertising stays True.

Also in the A version the uint16 10 ms duration tops out at 655 s, less than MAX_ANONYMOUS_ADV_TIMEOUT_SECS. But moving to A is the natural follow-on when anonymous=True is implemented properly, because that implementation would restart the set with a fresh random address each time the controller reports it terminated.

I added comments explaining the zero timeouts.

uint8_t max_ext_adv_evts[1] = { 0 };
hci_check_error(
hci_le_set_extended_advertising_enable(
Expand All @@ -684,8 +700,6 @@ uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,
duration_10msec,
max_ext_adv_evts
));

self->extended_advertising = true;
} else {
// Legacy advertising (not extended).

Expand Down Expand Up @@ -732,7 +746,6 @@ uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,

// Start advertising.
hci_check_error(hci_le_set_advertising_enable(BT_HCI_LE_ADV_ENABLE));
self->extended_advertising = false;
} // end legacy advertising setup

vm_used_ble = true;
Expand Down Expand Up @@ -790,10 +803,18 @@ void common_hal_bleio_adapter_stop_advertising(bleio_adapter_obj_t *self) {
check_enabled(self);

self->now_advertising = false;
self->extended_advertising = false;
self->circuitpython_advertising = false;

int result = hci_le_set_advertising_enable(BT_HCI_LE_ADV_DISABLE);
int result;
if (adapter_uses_extended_advertising(self)) {
// Duration and max events are ignored when disabling.
uint8_t handle[1] = { 0 };
uint16_t duration_10msec[1] = { 0 };
uint8_t max_ext_adv_evts[1] = { 0 };
result = hci_le_set_extended_advertising_enable(BT_HCI_LE_ADV_DISABLE, 1, handle, duration_10msec, max_ext_adv_evts);
} else {
result = hci_le_set_advertising_enable(BT_HCI_LE_ADV_DISABLE);
}
// OK if we're already stopped. There seems to be an ESP32 HCI bug:
// If advertising is already off, then LE_SET_ADV_ENABLE does not return a response.
if (result != HCI_RESPONSE_TIMEOUT) {
Expand All @@ -807,7 +828,6 @@ void common_hal_bleio_adapter_stop_advertising(bleio_adapter_obj_t *self) {
// Don't ask the adapter to stop.
void bleio_adapter_advertising_was_stopped(bleio_adapter_obj_t *self) {
self->now_advertising = false;
self->extended_advertising = false;
self->circuitpython_advertising = false;
}

Expand Down
2 changes: 0 additions & 2 deletions devices/ble_hci/common-hal/_bleio/Adapter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,6 @@ typedef struct _bleio_adapter_obj_t {
digitalio_digitalinout_obj_t *cts_digitalinout;
bool allocated; // True when in use.
bool now_advertising;
bool extended_advertising;
bool circuitpython_advertising;
bool enabled;

Expand All @@ -56,7 +55,6 @@ typedef struct _bleio_adapter_obj_t {

uint16_t max_acl_buffer_len;
uint16_t max_acl_num_buffers;
uint16_t max_adv_data_len;
uint8_t features[8]; // Supported BLE features.

// All the local attributes for this device. The index into the list
Expand Down
19 changes: 18 additions & 1 deletion devices/ble_hci/common-hal/_bleio/hci.c
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Original file line number Diff line number Diff line change
Expand Up @@ -489,7 +489,9 @@ hci_result_t hci_send_acl_pkt(uint16_t handle, uint8_t cid, uint16_t data_len, u
acl_data_t *acl_data = (acl_data_t *)acl_pkt->data;
acl_pkt->pkt_type = H4_ACL;
acl_pkt->handle = handle;
acl_pkt->pb = ACL_DATA_PB_FIRST_FLUSH;
// Host-to-controller LE data must use the non-flushable start flag; NimBLE
// controllers (ESP32-C6) silently discard packets with ACL_DATA_PB_FIRST_FLUSH.
acl_pkt->pb = ACL_DATA_PB_FIRST_NON_FLUSH;
acl_pkt->bc = 0;
acl_pkt->data_len = (uint16_t)(sizeof(acl_data_t) + data_len);
acl_data->acl_data_len = data_len;
Expand Down Expand Up @@ -608,7 +610,9 @@ hci_result_t hci_le_set_extended_advertising_parameters(uint8_t handle, uint16_t
.prim_channel_map = prim_channel_map,
.own_addr_type = own_addr_type,
// .peer_addr set below.
.filter_policy = filter_policy,
.tx_power = tx_power,
.prim_adv_phy = prim_adv_phy,
.sec_adv_max_skip = sec_adv_max_skip,
.sec_adv_phy = sec_adv_phy,
.sid = sid,
Expand All @@ -619,6 +623,7 @@ hci_result_t hci_le_set_extended_advertising_parameters(uint8_t handle, uint16_t
sizeof_field(struct bt_hci_cp_le_set_ext_adv_param, prim_min_interval));
memcpy(params.prim_max_interval, (void *)&prim_max_interval,
sizeof_field(struct bt_hci_cp_le_set_ext_adv_param, prim_max_interval));
params.peer_addr.type = peer_addr->type;
memcpy(params.peer_addr.a.val, peer_addr->a.val, sizeof_field(bt_addr_le_t, a.val));
return send_command(BT_HCI_OP_LE_SET_EXT_ADV_PARAM, sizeof(params), &params);
}
Expand Down Expand Up @@ -672,6 +677,18 @@ hci_result_t hci_le_set_extended_advertising_data(uint8_t handle, uint8_t op, ui
return send_command(BT_HCI_OP_LE_SET_EXT_ADV_DATA, sizeof(params) - (max_len - valid_len), &params);
}

hci_result_t hci_le_set_extended_scan_response_data(uint8_t handle, uint8_t op, uint8_t frag_pref, uint8_t len, uint8_t data[]) {
const uint8_t max_len = sizeof_field(struct bt_hci_cp_le_set_ext_scan_rsp_data, data);
uint8_t valid_len = MIN(len, max_len);
struct bt_hci_cp_le_set_ext_scan_rsp_data params = {
.handle = handle,
.op = op,
.frag_pref = frag_pref,
.len = valid_len,
};
memcpy(params.data, data, valid_len);
return send_command(BT_HCI_OP_LE_SET_EXT_SCAN_RSP_DATA, sizeof(params) - (max_len - valid_len), &params);
}

hci_result_t hci_le_set_scan_response_data(uint8_t len, uint8_t data[]) {
struct bt_hci_cp_le_set_scan_rsp_data params = {
Expand Down
3 changes: 3 additions & 0 deletions devices/ble_hci/common-hal/_bleio/hci.h
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Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,9 @@ hci_result_t hci_le_set_advertising_parameters(uint16_t min_interval, uint16_t m
hci_result_t hci_le_set_extended_advertising_data(uint8_t handle, uint8_t op, uint8_t frag_pref, uint8_t len, uint8_t data[]);
hci_result_t hci_le_set_extended_advertising_enable(uint8_t enable, uint8_t set_num, uint8_t handle[], uint16_t duration[], uint8_t max_ext_adv_evts[]);
hci_result_t hci_le_set_extended_advertising_parameters(uint8_t handle, uint16_t props, uint32_t prim_min_interval, uint32_t prim_max_interval, uint8_t prim_channel_map, uint8_t own_addr_type, bt_addr_le_t *peer_addr, uint8_t filter_policy, int8_t tx_power, uint8_t prim_adv_phy, uint8_t sec_adv_max_skip, uint8_t sec_adv_phy, uint8_t sid, uint8_t scan_req_notify_enable);
// Sends at most one fragment (251 bytes); longer data is truncated.
// Returns HCI_OK or the HCI error status; no output values.
hci_result_t hci_le_set_extended_scan_response_data(uint8_t handle, uint8_t op, uint8_t frag_pref, uint8_t len, uint8_t data[]);

hci_result_t hci_le_set_random_address(uint8_t addr[6]);
hci_result_t hci_le_set_scan_enable(uint8_t enable, uint8_t filter_dup);
Expand Down
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