SPI download mode (Flash, not RAM) (ESF-225)

[FARLY7]

Is your feature request related to a problem?

Hi there,

Do you have any idea when the SPI download mode for Flash will be implemented? Or how much of a priority it is considered?

I have a design with an array of 4x ESP32-C3s driven by a single ESP32-S3. It would greatly simplify my design if I could update all devices over a single SPI bus. Right now, I am using a SPI-to-(4x)UART bridge IC, which is not ideal. Unfortunately, RAM boot is not an option, as the program is 900 KB in size.

Thanks,
Sean

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[github-actions]

Hi @FARLY7! 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 your detailed question regarding SPI download mode for Flash on the ESP32-C3.

Based on the available Espressif documentation, the ESP32-C3 does support an SPI Download Boot mode, which allows downloading binary files into flash using the SPI interface. This is distinct from the more common UART and USB download methods. According to the ESP32-C3 Technical Reference Manual, SPI Download Boot mode is enabled by specific strapping pin configurations (GPIO9 = 0, GPIO8 = 0, GPIO3 = 0, GPIO2 = 1). In this mode, users can download binary files into flash or into SRAM for execution. However, the documentation does not provide details about the availability or support status of this feature in Espressif’s official tools (such as esptool.py or the Flash Download Tool), nor does it mention a timeline or priority for its implementation in those tools.

Here is the relevant excerpt:

In SPI Download Boot mode, users can download binary files into flash using SPI interface. It is also possible to download binary files into SRAM and execute it from SRAM.
— ESP32-C3 Technical Reference Manual, Section 7.2 Boot Mode Control

At this time, the knowledge sources do not indicate that SPI download mode for Flash is supported by Espressif’s standard software tools, nor do they provide information about future plans or priorities for this feature. If you require this functionality, you may need to implement a custom solution or continue using your current workaround until official support is available.

If you need further clarification or want to track the status of this feature, I recommend reaching out directly to Espressif through their official support channels or forums.

Let me know if you need more technical details about the boot mode strapping or hardware setup.

[dobairoland]

Hi @FARLY7. We might be able to deliver this feature around the end of the year (the earliest). But I'm not able to promise it.