'ESPLoader' object has no attribute 'CHIP_DETECT_MAGIC_VALUE' (ESPTOOL-944)

[brentpicasso]

Operating System

Linux

Esptool Version

4.8.1

Python Version

3.11.9

Chip Description

ESP32-S3

Device Description

ESP32-S3 connected to host via USB

Hardware Configuration

n/a

How is Esptool Run

via python code

Full Esptool Command Line that Was Run

via python code

Esptool Output

Custom python code is crashing when detecting chip. 

AttributeError: 'ESPLoader' object has no attribute 'CHIP_DETECT_MAGIC_VALUE'

It appears there is a bug in the ESPLoader where the CHIP_DETECT_MAGIC_VALUE is not defined, in two places:

https://github.com/espressif/esptool/blob/master/esptool/loader.py#L760 https://github.com/espressif/esptool/blob/master/esptool/loader.py#L763

This is my code snippet:

                for try_port in available_ports:
                    Logger.info(f"Trying to detect bootloader on port {try_port}")
                    try:
                        esp = esptool.ESPLoader(port=try_port.device, baud=cls.INITIAL_BAUDRATE)
                        esp.connect()
                        chip_desc = esp.get_chip_description()
                        Logger.info(f"Detected bootloader on port {try_port} : {chip_desc}")
                        port = try_port
                        esp = esp.run_stub()
                        with open(filename, 'rb') as firmware:
                            firmware_data = firmware.read()

                        esp.flash_data(firmware_data, progress_callback=_progress_callback)                            

                    except esptool.FatalError:
                        Logger.info(f"Bootloader not found on {try_port}")

### More Information

_No response_

### Other Steps to Reproduce

_No response_

### I Have Read the Troubleshooting Guide

- [X] I confirm I have read the troubleshooting guide.

[radimkarnis]

Hello @brentpicasso, please see the docstring of the ESPLoader class:

    Don't instantiate this base class directly, either instantiate a subclass or
    call cmds.detect_chip() which will interrogate the chip and return the
    appropriate subclass instance. You can also use a context manager as
    "with detect_chip() as esp:" to ensure the serial port is closed when done.

Initiating the esp object as esp = esptool.ESPLoader(port=try_port.device, baud=cls.INITIAL_BAUDRATE) is wrong. Either use a specific ROM class (e.g. ESP32C5ROM) or interrogate the chip first.

[brentpicasso]

thanks for the tip, I made further progress. :+1: