yc_client/components/esp_ble_ota/examples/ble_ota/README.md

ESP BLE OTA Demo description

ble ota demo is based on the ble ota component, it receives firmware via BLE and writes it to flash, sector by sector, until the upgrade is complete.

1. Services definition

The component contains two services:

• DIS Service: Displays software and hardware version information
• OTA Service: It is used for OTA upgrade and contains 4 characteristics, as shown in the following table:

Characteristics	UUID	Prop	description
RECV_FW_CHAR	0x8020	Write, notify	Firmware received, send ACK
PROGRESS_BAR_CHAR	0x8021	Read, notify	Read the progress bar and report the progress bar
COMMAND_CHAR	0x8022	Write, notify	Send the command and ACK
CUSTOMER_CHAR	0x8023	Write, notify	User-defined data to send and receive

2. Data transmission

2.1 Command package format

unit	Command_ID	PayLoad	CRC16
Byte	Byte: 0 ~ 1	Byte: 2 ~ 17	Byte: 18 ~ 19

Command_ID:

• 0x0001: Start OTA, Payload bytes(2 to 5), indicates the length of the firmware. Other Payload is set to 0 by default. CRC16 calculates bytes(0 to 17).
• 0x0002: Stop OTA, and the remaining Payload will be set to 0. CRC16 calculates bytes(0 to 17).
• 0x0003: The Payload bytes(2 or 3) is the payload of the Command_ID for which the response will be sent. Payload bytes(4 to 5) is a response to the command. 0x0000 indicates accept, 0x0001 indicates reject. Other payloads are set to 0. CRC16 computes bytes(0 to 17).

2.2 Firmware package format

The format of the firmware package sent by the client is as follows:

unit	Sector_Index	Packet_Seq	PayLoad
Byte	Byte: 0 ~ 1	Byte: 2	Byte: 3 ~ (MTU_size - 4)

• Sector_Index：Indicates the number of sectors, sector number increases from 0, cannot jump, must be send 4K data and then start transmit the next sector, otherwise it will immediately send the error ACK for request retransmission.
• Packet_Seq：If Packet_Seq is 0xFF, it indicates that this is the last packet of the sector, and the last 2 bytes of Payload is the CRC16 value of 4K data for the entire sector, the remaining bytes will set to 0x0. Server will check the total length and CRC of the data from the client, reply the correct ACK, and then start receive the next sector of firmware data.

The format of the reply packet is as follows:

unit	Sector_Index	ACK_Status	CRC6
Byte	Byte: 0 ~ 1	Byte: 2 ~ 3	Byte: 18 ~ 19

ACK_Status:

• 0x0000: Success
• 0x0001: CRC error
• 0x0002: Sector_Index error, bytes(4 ~ 5) indicates the desired Sector_Index
• 0x0003：Payload length error

3. Sample APP

APP

4. Sample code

ESP BLE OTA

4.1 OTA update ESP32-H2

To construct the BLE OTA demo for the ESP32-H2 device, ensure you're using ESP-IDF version 5.0 or later. Currently, the ESP32-H2 doesn't support NimBLE OTA updates, so omit the instructions in section 5. Maintain the default configuration for the Bluetooth framework, where Bluedroid - Dual-mode is selected. To ensure compatibility with the sample app mentioned in section 3, deactivate BLE 5.0 features by navigating to:

1. Component config > Bluetooth > Bluedroid Options and deselect Enable BLE 5.0 features.
2. Component config > Bluetooth > Controller Options and deselect Enable BLE 5 feature.

5. NimBLE OTA

Configure the Project

idf.py menuconfig

• Component config → Bluetooth → Bluetooth → Host → NimBLE - BLE only

Note: For maximum throughput, set maximum MTU using

• Component config → Bluetooth → NimBLE Options → Preferred MTU size in octets as 517

5.1 OTA with Protocomm

Configure the Project

idf.py menuconfig

• Example Configuration → Type of OTA → Use protocomm layer for security
• Component config → OTA Manager → Type of OTA → Enable protocomm level security

5.2 Pre encrypted OTA

• For using pre encrypted OTA, the OTA file needs to be encrypted using private key
• For more info regarding encrypting file refer : esp_encrypted_img

Configure the Project

idf.py menuconfig

• If using ESP32S3 set Component config → Bluetooth → Bluetooth → NimBLE Options → NimBLE Host task stack size as 8192
• Example Configuration → Type of OTA → Use Pre-Encrypted OTA
• Component config → OTA Manager → Type of OTA → Enable pre encrypted OTA