Advanced Embedded Programming | Detailed Flowchart of DSPS Protocol Stack Software on DA14531 (Organized with DeepSeek)

01Introduction:

The DSPS (Dialog Serial Port Service) protocol stack is based on the BLE GATT protocol to implement serial data transmission. The core process is divided into four stages: initialization, connection management, data transmission, and low power control.

Initialization → Broadcasting/Scanning → Establishing Connection → Data Transmission → Sleep/Wake → Disconnect → Loop

02Detailed Flowchart Analysis

1. Initialization Stage

Hardware Initialization

Configure peripherals (GPIO, UART, SPI, etc.)

Initialize the BLE protocol stack and kernel (Riviera Waves RTOS)

Register DSPS Service

Register TX/RX Characteristics and Flow Control features in GATT.

Low Power Configuration

Enable extended sleep mode (CFG_EXT_SLEEP) and set default connection parameters (connection interval, slave latency).

2. Broadcasting and Connection Establishment

Peripheral Side

Start directed advertising (3 seconds cycle), enter extended sleep immediately after broadcasting.

The advertising data includes device name and UUID.

Central Side

Periodic scanning (e.g., 3 seconds cycle), parse advertising packets and filter target devices.

Call gapc_conn_param_update to initiate connection request.

3. Data Transmission Stage

Data Sending (TX)

The host sends data to the peripheral.

The peripheral actively pushes data through the Notify characteristic (RX).

Flow Control Mechanism

When the receive buffer is full, send pause/resume signals through the Flow Control Characteristic.

Error Handling

Check the checksum of the data, if an error occurs, trigger retransmission (ATT Error Response).

4. Low Power Management

Extended Sleep Mode

Call app_easy_sleep() to enter sleep when idle, wake up on BLE events or GPIO interrupts.

During connection, extend sleep time by adjusting Slave Latency.

Dynamic Power Optimization

Turn off unused peripherals (e.g., ADC, SPI) to reduce GPIO pull-up/pull-down power consumption.

5. Connection Disconnection and Recovery

Active Disconnection

After data transmission is complete, call gapc_disconnect to terminate the connection.

Timeout Handling

If no device is scanned or communication times out within 20 seconds, trigger scan_timeout_cb callback and enter low power mode.

03Code Examples for Key Nodes in Flowchart

1. Initialize DSPS Service

void user_app_init(void) {
    // Enable extended sleep
    arch_set_sleep_mode(ARCH_EXT_SLEEP_ON);
    // Register DSPS service
    sps_server_init();
    sps_client_init();
    // Configure advertising parameters
    app_easy_gap_advertise_start();
}

2. Data Sending Function

void send_data(uint8_t *data, uint16_t len) {
    // Send data via TX Characteristic
    sps_send_data(data, len);
    // Trigger sleep (if idle)
    app_easy_sleep();
}

3. Low Power Connection Parameter Configuration

static struct gapc_conn_param conn_params = {
    .intv_min = 160,   // 200ms (160 * 1.25ms)
    .intv_max = 160,
    .latency = 4,      // Actual wake interval = 200ms * 5 = 1 second
    .timeout = 600     // 6 seconds timeout
};

04Flowchart05References

SDK Documentation：

DSPS_Protocol_Stack.pdf

Example Projects：

ble_app_throughput, ble_app_profile

Low Power Design Guide：

UM-B-119_DA14531_SW_Platform_Reference