Connecting an ESP8266

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Connecting an ESP8266

Postby mooncactus » Mon Feb 27, 2017 3:21 pm

I wanted to hook an old, 4x2 pin ESP8266 to one of my (old, kickstarted) OpenMV boards. The ESP would be a slave handled by AT commands.

- I was not able to find such a setup so far. I know about the wifi shield, but I have many ESP of all kinds in my drawers, so it would make a nice use of them.

- also is the serial Tx/Rx shared with the USB on the openMV board? i.e. is there some conflict to be expected with the IDE when talking with the ESP from the openmv?

By the way this little camera is delightful to work with.

As a last question... I understand that the OpenMV cams were made for image analysis in mind, but I would love to see how good the image quality can be with a better lens.
I have no clue how much I should spend on it before the JPEG compression artefacts would make the investment meaningless.
Also, the M7 probably makes ore than the initial revision, because its larger RAM (hence better compressed image quality, but this is another story, since I can live with BMP and home made compression).
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Re: Connecting an ESP8266

Postby kwagyeman » Mon Feb 27, 2017 4:39 pm


There's no USB conflicts with the serial port on your OpenMV Cam and the PC. They are separate interfaces. You can use both at the same time.

As for image compression... so, the JPEG code we're using has low image quality because we removed a lot of features to minimize file size. If I had time I would go back and try to re-build up back the code so that it could do low and high quality JPEG images. But, I don't really have that right now. People want computer vision features more than taking better images.

Anyway, the best thing to do is just to take an image and then send it out the serial port as a BMP image. You should be able to saturate the EPS8266's WiFi link. If you want to achieve real time images then you have to JPEG compress. I guess you can say we've got "good" low file size JPEGs because we optimized for that.

Note that if you don't have enough RAM on board you can always save the JPEG to disk and then read it back in and send it to the serial port. When saving the JPEG to disk we're able to use something called the frame buffer stack which has a lot more free RAM than the MicroPython heap so we can have much higher quality JPEGs. But, this does mean you basically do a write to the SD card per image. So, it's not a good technique for long lasting operation.

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