How to deal with the characteristic read event?

[flywithme]

Hi:

I'm coding with the nrf52840 dk sample.

as we know, the gatt operate is notify,read, write, etc.

I have found the event about the write,and notify:

case BLE_GATTS_EVT_WRITE:

case BLE_GATTS_EVT_HVC:

but I could find the same event about the READ,

could you tell how to develop with the softdevice S140 API or event  about the read event?

only the solution is to notify the value by timer , then client to read the characteristic is changed.

[awneil]

flywithme said:

the (sic) nrf52840 dk sample

There are many examples for the nRF52840-DK - which particular one are you referring to?

[flywithme]

every sample. just like the examples\ble_peripheral\ble_app_hrs\pca10056\s140\arm5_no_packs.

for example. the ble_bas.c  for the characteristic  battery_level.

In the example, the battery_level changed by the timer.

But I don't want to create the timer.

I only want the battery_level will be changed, when the clinet to operate to read the characteristic.

[flywithme]

awneil

[Kenneth]

I suspect what you are interested in is GATTS read request with authorization then:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v7.2.0/group___b_l_e___g_a_t_t_s___r_e_a_d___r_e_q___a_u_t_h___m_s_c.html

So each time you receive an BLE_GATTS_EVT_RW_AUTHORIZE_REQUEST, then you can sample the battery level and afterwards write the updated value using sd_ble_gatts_rw_authorize_reply().

I expect you will need to modify the battery_level_char_add() function call to include:

add_descr_params.is_defered_read = true;

before calling descriptor_add() in battery_level_char_add() to change the behavior here.