Calculating flash size

geo.espressif
Posts: 28
Joined: Tue Mar 31, 2015 7:27 pm

Calculating flash size

Postby geo.espressif » Thu Oct 15, 2015 4:08 pm

Could someone explain the flash size characteristics of the ESP8266. So, I can see when I flash that it is detected as an '8MBit flash', which is indicated as '512KB + 512KB' using the flash tool in info when you hover over. This is also alluded to in the 1.4 SDK by the "512+512" folder containing 'user1.1024.new.2.bin'.

So the question is more specifically:

- What do the two parts '512' represent?
- Why don't they add up to 8MBit?
- What is the actual maximum flash size of an image I generate?

I might have missed a section in some document so please do refer if appropriate. Many thanks!

James

blubb
Posts: 116
Joined: Mon Jun 22, 2015 5:35 am

Re: Calculating flash size

Postby blubb » Fri Oct 16, 2015 4:44 am

2 * 512 kB == 1024 kB == 1 MB == 8 MBit

geo.espressif
Posts: 28
Joined: Tue Mar 31, 2015 7:27 pm

Re: Calculating flash size

Postby geo.espressif » Fri Oct 16, 2015 4:25 pm

Yeah got that, but why are there two? e.g. does my flash image have a maximum size of 512 or 1024?

blubb
Posts: 116
Joined: Mon Jun 22, 2015 5:35 am

Re: Calculating flash size

Postby blubb » Mon Oct 19, 2015 12:51 am

The OTA feature uses two images. While one is running, the other one can be flashed safely.

If you do not need OTA flashing, you can use the whole space for a single image.

This is all explained in the pdf files.

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