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Ardunio IDE: getting the memory size right...

PostPosted: Mon Feb 19, 2018 12:54 pm
by cspwcspw
I bought a cheap UNO+8266 all-in-one board. It arrived with firmware supporting version 0.21.0.0 of the AT command set. The chip is an ESP8266EX, and it has a WinBond 5Q32FVS1 memory module.
On Reset, I learn
2nd boot version : 1.2
SPI Speed : 40MHz
SPI Mode : QIO
SPI Flash Size : 4Mbit

Now I set up to use the Arduino, I call it a generic 8266 board, and it works and runs some sketches.

But by default, the Arduino IDE says I have only 512K (no SPIFFS). And the 8266 built-in example that checks my IDE flash config fails. It reports the real size as 4194304. So when I change the IDE config to either 4M (3M SPIFFS) or 4M (1M SPIFFS), it seems to work and the sketch says my config is OK. There are no other IDE options at 4M.

What should my IDE config be? Should I have 4M (4M SPIFFS), but no such IDE menu option exists?

thanks.
Peter

Re: Ardunio IDE: getting the memory size right...

PostPosted: Tue Feb 20, 2018 6:14 am
by schufti
Hi,
SPIFFS is something like a "built in HD" that one could access via spiffs library.
A 4M(4M SPIFFS) partitioning would leave no space for your sketch on the esp.
So any partitioning (with 1M or 4M SPIFFS) would suit your needs for simple sketches w/o using OTA or spiffs at all.
The selection would be relevant if you have need for large amounts of stored data and want to do OTA (over the air update). For OTA one needs twice the size of the sketch binary on flash. So if using 1/3 partition, the sketch may only be 512k in binarysize. As the max binary size of a sketch can only be 1M, a 2/2 partitioning would be optimal. The 3/1 partition wastes 1M. The 1/3 is optimal if no OTA needed.