If Status 1, this indicates the type of error. If Status is 1, this indicates the type of error.įor ESP32-S3 ROM (only, not the software loader) the final four bytes are used, but only the first two bytes contain status information: Status flag, success ( 0) or failure ( 1) The final bytes of the Data payload indicate command status:įor software loader the final two bytes indicate status (most commands return at least a two byte Data payload): Response value used by READ_REG command (see below). At least the length of the Status Bytes (2 or 4 bytes, see below). Same value as Command identifier in the request packet that trigged the response Usage depends on specific command.Įach received command will result in a response SLIP packet sent from the ESP chip to the host. Variable length data payload (0-65535 bytes, as indicated by Size parameter). Simple checksum of part of the data field (only used for some commands, see Checksum). Inside the packet, the packet consists of a header and a variable-length body. Command Packet Įach command is a SLIP packet initiated by the host and results in a response packet. The replacing is to be done after the checksum and lengths are calculated, so the packet length may be longer than the size field below. Within the packet, all occurrences of 0xC0 and 0xDB are replaced with 0xDB 0xDC and 0xDB 0xDD, respectively. The bootloader protocol uses SLIP packet framing for data transmissions in both directions.Įach SLIP packet begins and ends with 0xC0. The ESP chip responds to the request with a SLIP encoded response packet, including status information and any data as a payload. The host computer sends a SLIP encoded command request to the ESP chip. Pass -no-stub to esptool in order to disable the software stub loader. The software loader then replaces the ROM loader for all future interactions. The ESP32-S3 ROM loader serial protocol is similar to ESP8266, although ESP32-S3 adds some additional commands and some slightly different behaviour.īy default, esptool uploads a stub “software loader” to the IRAM of the chip. See Entering the Bootloader for details of this process. The UART bootloader runs on chip reset if certain strapping pins are set. This is technical documentation for the serial protocol used by the UART bootloader in the ESP chip ROM and the esptool software stub loader program.

Tracing esp ltd serial numbers