Changing trasmission power with nRF51822 (Bluetooth Smart Beacon Kit)

[classicman]

Hello everybody.

I'm trying to modify the original firmware that comes with the nRF51822 to make it sweep all of the permitted levels of transmission power. I was able to change the default transmission power by calling the function sd_ble_gap_tx_power_set() from within the advertising_start loop.

What I'm trying to do now is force the beacon to sweep trough all of the permitted power levels while in advertising mode. Digging up the code I have found a declaration in beacon.h:

define APP_BEACON_ADV_TIMEOUT 0 /++< Time for which the device must be advertising in non-connectable mode (in seconds). 0 disables timeout */

My idea is to set a certain value for APP_BEACON_ADV_TIMEOUT, and my guess is that an interrupt will be generated when the timer expires and the device stops advertising. I need help intercepting this interrupt.

Thanks.

[Roger Clark]

Have you tried registering a callback using

err_code = softdevice_ble_evt_handler_set(ble_evt_dispatch);

[Sigurd]

Hi,

First you will need to subscribe for BLE events, so in the function ble_stack_init(), you will need to add this:

err_code = softdevice_ble_evt_handler_set(ble_evt_dispatch);
APP_ERROR_CHECK(err_code);

All BLE events arrive at the ble_evt_dispatch() function, so here we can add your advertising timeout function:

static void ble_evt_dispatch(ble_evt_t * p_ble_evt)
{
    adv_timeout_on_ble_evt(p_ble_evt);
}

In the advertising timeout function you will need to check for the BLE event called BLE_GAP_EVT_TIMEOUT and with source BLE_GAP_TIMEOUT_SRC_ADVERTISING. You can then change the TX-power as you like, and then start the advertising again.

void adv_timeout_on_ble_evt(ble_evt_t * p_ble_evt){
    
    if(p_ble_evt->header.evt_id == BLE_GAP_EVT_TIMEOUT && 
       p_ble_evt->evt.gap_evt.params.timeout.src == BLE_GAP_TIMEOUT_SRC_ADVERTISING){
           //Change TX-power with sd_ble_gap_tx_power_set()
           advertising_start();
    }
        
}

[classicman]

Hello, thank you for the in-depth reply.

I followed your instructions, but instead of creating a new function like void adv_timeout_on_ble_evt() as you suggested, I stuffed my code inside the pre-existing on_ble_evt( ), inside the case BLE_GAP_EVT_TIMEOUT. I have set the timeout to 10 seconds, after which advertising_start()is called.

For the sake of those who might read this in the future, there was a minor mispell in your code, in fact the correct macro is BLE_GAP_TIMEOUT_SRC_ADVERTISEMENT and not BLE_GAP_TIMEOUT_SRC_ADVERTISING.

Thank you both again for your time and expertise.

[Sigurd]

Yes, for SoftDevice S110 the correct macro is BLE_GAP_TIMEOUT_SRC_ADVERTISEMENT. For SoftDevice S130/S132/S332 the macro is changed to BLE_GAP_TIMEOUT_SRC_ADVERTISING.