Add stub support for ESP8266 - waiting for esp-flasher-stub (ESF-228)

[liruya]

Port

esp32

Target chip

ESP8266

Hardware Configuration

Custom Board use ESP32S3FH4R2 as host
Target Chip: ESP8266
Baudrate: 115200
esp-serial-flasher version: 1.9.0

Log output

ESP_LOADER_ERROR_TIMEOUT

More Information

My board use esp32s3 as host, when i flash binaries to esp8266 or erase esp8266 use stub mode, badurate 115200, log output error: ESP_LOADER_ERROR_TIMEOUT.
This happens at invoke "esp_loader_connect_with_stub" function.
But i can erase or flash esp8266 without stub mode.

[github-actions]

Hi @liruya! Please be aware that (1) the following suggestions are generated by a bot and haven't been fact-checked by Espressif Systems, (2) burning eFuses and enabling security features are irreversible operations and can damage your ESP32 device. We hope that this message will help you until an Espressif Engineer looks at your issue.

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Thank you for providing detailed information about your setup and the issue.

Based on the knowledge sources, the esp-serial-flasher library does support ESP8266 as a target, and stub mode is generally used to improve flashing performance and reliability. However, your log shows a timeout error (ESP_LOADER_ERROR_TIMEOUT) when invoking esp_loader_connect_with_stub() for ESP8266, while non-stub mode works as expected.

Key Points from Documentation:

• The stub loader is a small application uploaded to the target device to optimize flashing operations. For ESP8266, the stub loader is supported and should be used by default for better performance, unless explicitly disabled [esp-serial-flasher documentation].
• If you encounter issues with the stub loader, you can disable it and fall back to the ROM bootloader, which is what you have already confirmed works [esptool flasher stub].
• There is an open issue (ESF-228) regarding adding support for the new esp-flasher-stub for ESP8266. The documentation and example projects indicate that the stub binaries are embedded from a fixed release, and if a new version is needed, it must be pulled or overridden manually [esp-serial-flasher example].

Possible Causes and Recommendations:

1. Stub Binary Availability:
   The error may be due to the current version of esp-serial-flasher not including a compatible or updated stub for ESP8266. The documentation and your issue reference (ESF-228) suggest that full support for the new esp-flasher-stub for ESP8266 is pending. If the stub binary is missing or incompatible, the connection will fail with a timeout.

2. Workaround:
   Since flashing and erasing work without the stub, continue using non-stub mode for ESP8266 until the new stub support is officially released. You can disable the stub by configuring your build or using the appropriate API/option.

3. Monitor for Updates:
   Keep an eye on the esp-serial-flasher repository and the esp-flasher-stub project for updates regarding ESP8266 stub support. Once the new stub is available and integrated, you should be able to use stub mode reliably.

Summary:
Your observation is correct: stub mode currently does not work for ESP8266 with your setup, likely due to pending support for the new esp-flasher-stub. Non-stub mode is the recommended workaround until the new stub is released and integrated. There is no additional troubleshooting step in the knowledge sources that would resolve this until the stub support is updated.

If you need to override or update the stub binaries in the future, refer to the example documentation for instructions on pulling or overriding stub sources [esp-serial-flasher example].

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If you have further questions or need help monitoring the status of ESF-228, please let us know!

[liruya]

I try use rate 74880, also fail to connect esp8266 use stub mode.

[dobairoland]

I believe that stub mode with ESP8266 is not supported at the moment because https://github.com/esp-rs/esp-flasher-stub/ is used as a stub which doesn't have support for ESP8266.

We are developing a new stub (with ESP8266 support as well) which will be used in this project.

[Dzarda7]

Hello @liruya, the reason why this does not work is that we use esp-flasher-stub in this project which does not support esp8266. If you really need a stub for esp8266 you can follow these instructions on how to provide your own URL and include this one. But I am suggesting against it and using the esp_loader_connect instead.

[Dzarda7]

Anyway I will take a look if the error messaging can be improved somehow when the stub is not supported, thanks for bringing this up.

[liruya]

ok, when i flash esp8266 without stub mode, if rate > 115200, the chances of failure is high. how to improve the chance of success.

[Dzarda7]

Can you provide more info please? If it fails just occasionally, it can be a hardware issue.