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extmod/modbluetooth: Allow config of scan interval/window.

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This adds two additional optional kwargs to `gap_scan()`:
  - `interval_us`: How long between scans.
  - `window_us`: How long to scan for during a scan.

The default with NimBLE is a 11.25ms window with a 1.28s interval.

Changing these parameters is important for detecting low-frequency
advertisements (e.g. beacons).

Note: these params are in microseconds, not milliseconds in order
to allow the 625us granularity offered by the spec.
This commit is contained in:
Jim Mussared 2019-10-08 14:25:32 +11:00
parent 06ae818f93
commit b65cc387cd
3 changed files with 23 additions and 20 deletions
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31
extmod/modbluetooth.c
View File

@ -501,23 +501,26 @@ STATIC mp_obj_t bluetooth_ble_gap_connect(size_t n_args, const mp_obj_t *args) {
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gap_connect_obj, 3, 4, bluetooth_ble_gap_connect); STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gap_connect_obj, 3, 4, bluetooth_ble_gap_connect);
STATIC mp_obj_t bluetooth_ble_gap_scan(size_t n_args, const mp_obj_t *args) { STATIC mp_obj_t bluetooth_ble_gap_scan(size_t n_args, const mp_obj_t *args) {
if (n_args == 2 && args[1] == mp_const_none) { // Default is indefinite scan, with the NimBLE "background scan" interval and window.
int err = mp_bluetooth_gap_scan_stop(); mp_int_t duration_ms = 0;
return bluetooth_handle_errno(err); mp_int_t interval_us = 1280000;
} else { mp_int_t window_us = 11250;
mp_int_t duration_ms = 0; if (n_args > 1) {
if (n_args == 2) { if (args[1] == mp_const_none) {
if (!mp_obj_is_int(args[1])) { // scan(None) --> stop scan.
mp_raise_ValueError("invalid duration"); return bluetooth_handle_errno(mp_bluetooth_gap_scan_stop());
} }
duration_ms = mp_obj_get_int(args[1]); duration_ms = mp_obj_get_int(args[1]);
if (n_args > 2) {
interval_us = mp_obj_get_int(args[2]);
if (n_args > 3) {
window_us = mp_obj_get_int(args[3]);
}
} }
int err = mp_bluetooth_gap_scan_start(duration_ms);
return bluetooth_handle_errno(err);
} }
return bluetooth_handle_errno(mp_bluetooth_gap_scan_start(duration_ms, interval_us, window_us));
} }
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gap_scan_obj, 1, 2, bluetooth_ble_gap_scan); STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gap_scan_obj, 1, 4, bluetooth_ble_gap_scan);
#endif // MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE #endif // MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE
STATIC mp_obj_t bluetooth_ble_gap_disconnect(mp_obj_t self_in, mp_obj_t conn_handle_in) { STATIC mp_obj_t bluetooth_ble_gap_disconnect(mp_obj_t self_in, mp_obj_t conn_handle_in) {

2
extmod/modbluetooth.h
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@ -186,7 +186,7 @@ int mp_bluetooth_gap_disconnect(uint16_t conn_handle);
#if MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE #if MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE
// Start a discovery (scan). Set duration to zero to run continuously. // Start a discovery (scan). Set duration to zero to run continuously.
int mp_bluetooth_gap_scan_start(int32_t duration_ms); int mp_bluetooth_gap_scan_start(int32_t duration_ms, int32_t interval_us, int32_t window_us);
// Stop discovery (if currently active). // Stop discovery (if currently active).
int mp_bluetooth_gap_scan_stop(void); int mp_bluetooth_gap_scan_stop(void);

10
extmod/modbluetooth_nimble.c
View File

@ -614,16 +614,16 @@ STATIC int gap_scan_cb(struct ble_gap_event *event, void *arg) {
return 0; return 0;
} }
int mp_bluetooth_gap_scan_start(int32_t duration_ms) { int mp_bluetooth_gap_scan_start(int32_t duration_ms, int32_t interval_us, int32_t window_us) {
if (duration_ms == 0) { if (duration_ms == 0) {
duration_ms = BLE_HS_FOREVER; duration_ms = BLE_HS_FOREVER;
} }
STATIC const struct ble_gap_disc_params discover_params = { struct ble_gap_disc_params discover_params = {
.itvl = BLE_GAP_SCAN_SLOW_INTERVAL1, .itvl = MAX(BLE_HCI_SCAN_ITVL_MIN, MIN(BLE_HCI_SCAN_ITVL_MAX, interval_us / BLE_HCI_SCAN_ITVL)),
.window = BLE_GAP_SCAN_SLOW_WINDOW1, .window = MAX(BLE_HCI_SCAN_WINDOW_MIN, MIN(BLE_HCI_SCAN_WINDOW_MAX, window_us / BLE_HCI_SCAN_ITVL)),
.filter_policy = BLE_HCI_CONN_FILT_NO_WL, .filter_policy = BLE_HCI_CONN_FILT_NO_WL,
.limited = 0, .limited = 0,
.passive = 0, .passive = 1, // TODO: Handle BLE_HCI_ADV_RPT_EVTYPE_SCAN_RSP in gap_scan_cb above.
.filter_duplicates = 0, .filter_duplicates = 0,
}; };
int err = ble_gap_disc(BLE_OWN_ADDR_PUBLIC, duration_ms, &discover_params, gap_scan_cb, NULL); int err = ble_gap_disc(BLE_OWN_ADDR_PUBLIC, duration_ms, &discover_params, gap_scan_cb, NULL);