Update BLE Characteristic from ENUM

[aplatts]

Hi

I would like to use an ENUM and STUCT within my application to maintain device state (IDLE, RUNNING etc). This state needs to update a BLE Characteristic. I have the BLE Service and Characteristic running but am struggling to send the ENUM as a single byte (uint8_t).

The ENUM & STRUCT is as follows:

typedef enum
{
    IDLE    = 0x00,    //0
    RUNNING = 0x01,    //1
    FAULT   = 0x09     //9
} m_srm_state_evt_type_t;

typedef struct
{
    m_srm_state_evt_type_t evt_type;
} m_srm_state_type_t;
static m_srm_state_type_t m_srm_state;

And the BLE update char is as follows:

case BLE_SRVC_OPT_EVT_CONNECTED:
            uint8_t value[1]            = {m_srm_state.value};
            err_code = ble_srvc_opt_custom_value_update(&m_cus, value);
            APP_ERROR_CHECK(err_code);
            break;

I know it's my lack of programming skills, but really stuck on this one. Thanks in advance.

[Jared]

Hi,

I'm interested in seeing more of your code, specifically the initialization of the service and the ble_srvc_opt_custom_value_update(). Also

I have the BLE Service and Characteristic running but am struggling to send the ENUM as a single byte (uint8_t).

 What exactly happens when you run the application? Are you getting any errors? Have you tried debugging your application?

regards

Jared

[aplatts]

Hi

I think the issue is that I am attempting to send a Characteristic Value before it being ready (i.e. I'm sending as soon as BLE_SRVC_OPT_EVT_CONNECTED). As this is at the Service level, I assume that the Characteristic could still be being negotiated.

Would this make sense?

[Jared]

Hi,

Did you try the workaround suggest in the linked case in the previous reply? 

You could try setting err_code =sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0)  before you call  ble_srvc_opt_custom_value_update(). And you should make sure that notifications is enabled.

regards

Jared

[aplatts]

Hi

I have looked at my code and carried out a few modifications and have a better understand how the SoftDevice works.

The following is working, on the following event, it calls handle_ble_char:

case BLE_SRVC_OPT_EVT_CONNECTED:
        t_value = SET;
        handle_ble_char(p_cus_service, &p_cus_service->status_char_handles , &t_value);
        break;

The structure of handle_ble_char is as follows:

static void handle_ble_char (ble_srvc_opt_t *p_service, ble_gatts_char_handles_t *p_char_handle, m_setget *p_type) {

    uint32_t err_code;
    ble_gatts_value_t	t_value;

    //Get & Set for ble_src_opt - Char - Status
    if (p_char_handle->value_handle == m_cus.status_char_handles.value_handle) {
        
        t_value.p_value = &m_srm_state.evt_type;
	    t_value.len      = 1;
	    t_value.offset   = 0;

        switch (*p_type)
        {
        case SET:
            err_code = sd_ble_gatts_value_set(p_service->conn_handle, p_char_handle->value_handle, &t_value);
    	    APP_ERROR_CHECK(err_code);
            break;
        case GET:
            err_code = sd_ble_gatts_value_get(p_service->conn_handle, p_char_handle->value_handle, &t_value);
    	    APP_ERROR_CHECK(err_code);
            break;
        default:
            break;
        }
    }

}

This is a universal bit of code which allows me to tell it which service and characteristic to set or get.

It is working as planned now...thanks for the help on this one.