BLE esp_ble_gatts_send_response() clarification
Posted: Wed Sep 15, 2021 9:10 am
Hello. I am learning the BLE and want to confirm regarding the esp_ble_gatts_send_response() method. I use lightblue app to connect between my ESP32 device and my phone.
When I click read on my lightblue APP, the read event is triggered and in my code, the following code is executed:
I can see the string "read" dispalyed on my lightblue app. So the esp_ble_gatts_send_response sends the data to the lightblue app right?
Now during my write event:
As you can see, in my write event, I have this code:
Since my characteristic is set to ESP_GATT_RSP_BY_APP this gets triggered and I want to display the string "write" as a response. But this does not get displayed on my lightblue app. Can someone help me understand why
When I click read on my lightblue APP, the read event is triggered and in my code, the following code is executed:
Code: Select all
case ESP_GATTS_READ_EVT:
ESP_LOGI(GATTS_TABLE_TAG, "ESP_GATTS_READ_EVT");
esp_gatt_rsp_t rsp;
memset(&rsp, 0, sizeof(esp_gatt_rsp_t));
rsp.attr_value.handle = param->read.handle;
rsp.attr_value.len = 4;
rsp.attr_value.value[0] = 'r';
rsp.attr_value.value[1] = 'e';
rsp.attr_value.value[2] = 'a';
rsp.attr_value.value[3] = 'd';
esp_ble_gatts_send_response(gatts_if, param->write.conn_id, param->write.trans_id, ESP_GATT_OK, &rsp);
break;
Now during my write event:
Code: Select all
case ESP_GATTS_WRITE_EVT:
if (!param->write.is_prep){
// the data length of gattc write must be less than GATTS_DEMO_CHAR_VAL_LEN_MAX.
ESP_LOGI(GATTS_TABLE_TAG, "GATT_WRITE_EVT, handle = %d, value len = %d, value :", param->write.handle, param->write.len);
esp_log_buffer_hex(GATTS_TABLE_TAG, param->write.value, param->write.len);
if (heart_rate_handle_table[IDX_CHAR_CFG_C] == param->write.handle && param->write.len == 2){
printf("inside if statement\n");
uint16_t descr_value = param->write.value[1]<<8 | param->write.value[0];
if (descr_value == 0x0001){
ESP_LOGI(GATTS_TABLE_TAG, "notify enable");
uint8_t notify_data[15];
for (int i = 0; i < sizeof(notify_data); ++i)
{
notify_data[i] = i % 0xff;
}
//the size of notify_data[] need less than MTU size
esp_ble_gatts_send_indicate(gatts_if, param->write.conn_id, heart_rate_handle_table[IDX_CHAR_VAL_C],
sizeof(notify_data), notify_data, false);
}else if (descr_value == 0x0002){
ESP_LOGI(GATTS_TABLE_TAG, "indicate enable");
uint8_t indicate_data[15];
for (int i = 0; i < sizeof(indicate_data); ++i)
{
indicate_data[i] = i % 0xff;
}
//the size of indicate_data[] need less than MTU size
esp_ble_gatts_send_indicate(gatts_if, param->write.conn_id, heart_rate_handle_table[IDX_CHAR_VAL_C],
sizeof(indicate_data), indicate_data, true);
}
else if (descr_value == 0x0000){
ESP_LOGI(GATTS_TABLE_TAG, "notify/indicate disable ");
}else{
ESP_LOGE(GATTS_TABLE_TAG, "unknown descr value");
esp_log_buffer_hex(GATTS_TABLE_TAG, param->write.value, param->write.len);
}
}
// THIS WILL NEVER TRIGGER IF AUTO RSP IS SET
/* send response when param->write.need_rsp is true*/
if (param->write.need_rsp){
printf("******************PARAM NEED RESPONSE****************\n");
esp_gatt_rsp_t rsp;
memset(&rsp, 0, sizeof(esp_gatt_rsp_t));
rsp.attr_value.handle = param->read.handle;
rsp.attr_value.len = 5;
rsp.attr_value.value[0] = 'w';
rsp.attr_value.value[1] = 'r;
rsp.attr_value.value[2] = 'i';
rsp.attr_value.value[3] = 't';
rsp.attr_value.value[4] = 'e';
esp_ble_gatts_send_response(gatts_if, param->write.conn_id, param->write.trans_id, ESP_GATT_OK, &rsp);
}
}else{
/* handle prepare write */
printf("before exmaple prepare write event env \n");
example_prepare_write_event_env(gatts_if, &prepare_write_env, param);
}
break;
Code: Select all
if (param->write.need_rsp){
printf("******************PARAM NEED RESPONSE****************\n");
esp_gatt_rsp_t rsp;
memset(&rsp, 0, sizeof(esp_gatt_rsp_t));
rsp.attr_value.handle = param->read.handle;
rsp.attr_value.len = 5;
rsp.attr_value.value[0] = 'w';
rsp.attr_value.value[1] = 'r;
rsp.attr_value.value[2] = 'i';
rsp.attr_value.value[3] = 't';
rsp.attr_value.value[4] = 'e';
esp_ble_gatts_send_response(gatts_if, param->write.conn_id, param->write.trans_id, ESP_GATT_OK, &rsp);
}