feat(ble/bluedroid): Add Read Long Characteristic Values example

2025-02-25 16:20:42 +08:00
parent 837311c0ff
commit 32e4fb79e8
3 changed files with 130 additions and 25 deletions
@@ -673,24 +673,59 @@ bool need_rsp;             /*!< The read operation need to do response */

 In this example, a response is constructed with dummy data and sent back to the host using the same handle given by the event. In addition to the response, the GATT interface, the connection ID and the transfer ID are also included as parameters in the `esp_ble_gatts_send_response()` function. This function is necessary if the auto response byte is set to NULL when creating the characteristic or descriptor.

+This example also implements the Read Long Characteristic Values procedure, efficiently handling fragmented read requests while dynamically adapting to connection-specific MTU sizes.
+
 ```c
 case ESP_GATTS_READ_EVT: {
-     ESP_LOGI(GATTS_TAG, "GATT_READ_EVT, conn_id %d, trans_id %d, handle %d",
-              param->read.conn_id, param->read.trans_id, param->read.handle);
-              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] = 0xde;
-              rsp.attr_value.value[1] = 0xed;
-              rsp.attr_value.value[2] = 0xbe;
-              rsp.attr_value.value[3] = 0xef;
-              esp_ble_gatts_send_response(gatts_if,
-                                          param->read.conn_id,
-                                          param->read.trans_id,
-                                          ESP_GATT_OK, &rsp);
-     break;
+    ESP_LOGI(GATTS_TAG,
+                "Characteristic read request: conn_id=%d, trans_id=%" PRIu32 ", handle=%d, is_long=%d, offset=%d, need_rsp=%d",
+                param->read.conn_id, param->read.trans_id, param->read.handle,
+                param->read.is_long, param->read.offset, param->read.need_rsp);
+
+    // If no response is needed, exit early (stack handles it automatically)
+    if (!param->read.need_rsp) {
+        return;
    }
+
+    esp_gatt_rsp_t rsp;
+    memset(&rsp, 0, sizeof(esp_gatt_rsp_t));
+    rsp.attr_value.handle = param->read.handle;
+
+    // Handle descriptor read request
+    if (param->read.handle == gl_profile_tab[PROFILE_A_APP_ID].descr_handle) {
+        memcpy(rsp.attr_value.value, &descr_value, 2);
+        rsp.attr_value.len = 2;
+        esp_ble_gatts_send_response(gatts_if, param->read.conn_id, param->read.trans_id, ESP_GATT_OK, &rsp);
+        return;
+    }
+
+    // Handle characteristic read request
+    if (param->read.handle == gl_profile_tab[PROFILE_A_APP_ID].char_handle) {
+        uint16_t offset = param->read.offset;
+
+        // Validate read offset
+        if (param->read.is_long && offset > CONFIG_EXAMPLE_CHAR_READ_DATA_LEN) {
+            ESP_LOGW(GATTS_TAG, "Read offset (%d) out of range (0-%d)", offset, CONFIG_EXAMPLE_CHAR_READ_DATA_LEN);
+            rsp.attr_value.len = 0;
+            esp_ble_gatts_send_response(gatts_if, param->read.conn_id, param->read.trans_id, ESP_GATT_INVALID_OFFSET, &rsp);
+            return;
+        }
+
+        // Determine response length based on MTU
+        uint16_t mtu_size = local_mtu - 1;  // ATT header (1 byte)
+        uint16_t send_len = (CONFIG_EXAMPLE_CHAR_READ_DATA_LEN - offset > mtu_size) ? mtu_size : (CONFIG_EXAMPLE_CHAR_READ_DATA_LEN - offset);
+
+        memcpy(rsp.attr_value.value, &char_value_read[offset], send_len);
+        rsp.attr_value.len = send_len;
+
+        // Send response to GATT client
+        esp_err_t err = esp_ble_gatts_send_response(gatts_if, param->read.conn_id, param->read.trans_id, ESP_GATT_OK, &rsp);
+        if (err != ESP_OK) {
+            ESP_LOGE(GATTS_TAG, "Failed to send response: %s", esp_err_to_name(err));
+        }
+    }
+    break;
+}
 ```

 ## Managing Write Events