Image built at QIO but programmed as DIO (ESP12-F not compatible ESP-12E)

[gailu]

Hi Experts,

We are using ESP in production. Our thousands of devices already deployed in field and having ESP-12E. We have purchased new 1000 pcs of ESP-12F from AI-Thinker two weeks back because their sales person confirmed us that ESP-12F is backward compatible with ESP-12E. However our testing shows that ESP-12F is not fully backward compatible with ESP-12E. Changes seems to be related to SPI flash. We have built ESP images and selected QIO mode. This image works fine with ESP-12E when burned with QIO mode selected in programmer. However same image does not work with ESP-12F when QIO mode selected in programmer though same image works when DIO is selected in flash programmer.

I know that we should build image as DIO mode and flash as DIO mode as recommended, but we have lots of operational challenges. We support OTA upgrades and if we change images on our server with DIO mode for new modules our existing devices burned as QIO mode will download DIO image and may cause issues to our existing users. so we have to put lots of check for different devices to download different images and need to maintain multiple images.

I have two questions in this regard as we want to keep only one image that works with both modules.

1) What could be the problem if an image is build with QIO mode but flashed as DIO mode?
2) What could be the problem if an image is build with DIO mode and updated through OTA?

It is very irresponsible from AI-Thinker that they made SPI related changes and didn't inform us before buying though the question has been explicitly asked. But we have to live with it, not sure when will they understand operational challenges of their customers. We have purchased ESP-12F samples and tested that before ordering and they did not have this issue. Its only latest lot from AI-Thinker where we faced this QIO mode issue.

Please help us with the answers to above two queries, Our production is halted and not sure what to do next.

Thank you.

[pratik]

That's sad.
Are you directly getting your modules from AI-Thinker? We would strongly suggets using just QIO or just DIO for ALL modules.
I personally like to compile all programs for DIO mode, and it runs a little slower than QIO but it will always run on both DIO and QIO flash.
If you compile and enable QIO, but your flash supports DIO only, then the ESP will be bricked and display checksum error.

A note on ESP-12:
There are MANY vendors that brand ESP12 type modules as "AI thinker". Your R&D team should remove the shielding can and take a look at what's inside. Make sure the lot you are buying are genuine AI Thinker. I have many modules that are FAKE and get bricked on QIO mode, even though the flash is QIO (seems the flash chips are fakes).
You can opt for ESP-WROOM-02 modules for full support and guarantee of functionality.

For now:
The ESP12F is QIO mode and compatible with ESP12E. Please check if the modules you got are genuine!
If yes, see if your existing devices support DIO. Then issue updates accordingly.

[gailu]

We have purchased directly from AI-Thinker. Their sales rep email Id is on aithinker.com domain. We can send you a sample of ESP-12F if required.Payment is done to Bank Account in the name of Shenzen AI-Thinker Co. Ltd.

I expect genuine module from them. Are you sure that they have not changed flash recently in ESP-12F?

[pratik]

I work remotely with Espressif, I'm based in India. I have ESP-12E and ESP-12F modules labeled AI Thinker that work in both DIO and QIO very well.
They should not change flash in recent versions without labeling it as a different part. QIO programs will be bricked if run on DIO board!
Can't they supply QIO mode ones? Maybe something is wrong with samples.

[gailu]

We also have ESP-12F (labelled AI-Thinker) purchased in India from eBay.in in which QIO mode works. But we also have ESP-12F purchased directly from AI-Thinker imported in July second week where QIO mode doesn't work.

[pratik]

Yes, almost all ESP-12Fs bought here work with QIO. We have had some non-AI-Thinker modules with a pacman on the shielding can. Those are the onces that do not work with QIO even though they are specified as QIO. I did not open the can up and check the insides of that. But they are not AI-Thinker branded.
Maybe the fakes are QIO and the original is DIO? That would be crazy.