sys/supervisor: shutdown if no BLE connection within 30 seconds

This shuts down hubs if no BLE connection is made with 30 seconds. This
is done to save battery. This is particularly important on SPIKE Prime/
MINDSTORMS Inventor since it is very easy to accidentally to press the
power button without knowing it.

Fixes pybricks/support#79

Author: dlech

lib/pbio/drv/bluetooth/bluetooth_btstack.c

@@ -187,7 +187,6 @@ PROCESS_THREAD(pbdrv_bluetooth_hci_process, ev, data) {
         init_advertising_data();
         gap_advertisements_enable(true);
 
-        // TODO: we should have a timeout and stop scanning eventually
         // TODO: allow user programs to initiate BLE connections
         pbsys_status_set(PBSYS_STATUS_BLE_ADVERTISING);
         PROCESS_WAIT_UNTIL(con_handle != HCI_CON_HANDLE_INVALID || pbsys_status_test(PBSYS_STATUS_USER_PROGRAM_RUNNING));

lib/pbio/drv/city_hub/bluetooth.c

@@ -1207,7 +1207,6 @@ PROCESS_THREAD(pbdrv_bluetooth_hci_process, ev, data) {
         PROCESS_PT_SPAWN(&child_pt, init_uart_service(&child_pt));
         PROCESS_PT_SPAWN(&child_pt, set_discoverable(&child_pt));
 
-        // TODO: we should have a timeout and stop scanning eventually
         // TODO: allow user programs to initiate BLE connections
         pbsys_status_set(PBSYS_STATUS_BLE_ADVERTISING);
         PROCESS_WAIT_UNTIL(conn_handle != NO_CONNECTION || pbsys_status_test(PBSYS_STATUS_USER_PROGRAM_RUNNING));

lib/pbio/drv/move_hub/bluetooth.c

@@ -664,7 +664,6 @@ PROCESS_THREAD(pbdrv_bluetooth_hci_process, ev, data) {
         PROCESS_PT_SPAWN(&child_pt, init_uart_service(&child_pt));
         PROCESS_PT_SPAWN(&child_pt, set_discoverable(&child_pt));
 
-        // TODO: we should have a timeout and stop scanning eventually
         // TODO: allow user programs to initiate BLE connections
         pbsys_status_set(PBSYS_STATUS_BLE_ADVERTISING);
         PROCESS_WAIT_UNTIL(conn_handle || pbsys_status_test(PBSYS_STATUS_USER_PROGRAM_RUNNING));

lib/pbio/drv/technic_hub/bluetooth.c

@@ -1204,7 +1204,6 @@ PROCESS_THREAD(pbdrv_bluetooth_hci_process, ev, data) {
         PROCESS_PT_SPAWN(&child_pt, init_uart_service(&child_pt));
         PROCESS_PT_SPAWN(&child_pt, set_discoverable(&child_pt));
 
-        // TODO: we should have a timeout and stop scanning eventually
         // TODO: allow user programs to initiate BLE connections
         pbsys_status_set(PBSYS_STATUS_BLE_ADVERTISING);
         PROCESS_WAIT_UNTIL(conn_handle != NO_CONNECTION || pbsys_status_test(PBSYS_STATUS_USER_PROGRAM_RUNNING));

lib/pbio/sys/supervisor.c

@@ -18,7 +18,9 @@
  */
 void pbsys_supervisor_poll() {
     // Shut down on low voltage so we don't damage rechargeable batteries
-    if (pbsys_status_test_debounce(PBSYS_STATUS_BATTERY_LOW_VOLTAGE_SHUTDOWN, true, 3000)) {
+    // or if there is no BLE connection made whithin 30 seconds
+    if (pbsys_status_test_debounce(PBSYS_STATUS_BATTERY_LOW_VOLTAGE_SHUTDOWN, true, 3000)
+        || pbsys_status_test_debounce(PBSYS_STATUS_BLE_ADVERTISING, true, 30000)) {
         // REVISIT: this assumes that the power button is not pressed and USB is
         // not plugged in so that the power will actually turn off here
         pbdrv_reset(PBDRV_RESET_ACTION_POWER_OFF);