ESP8266 Community Forum

- Mon Aug 31, 2015 2:53 pm #27478 Is there any function, to read out the actual free RAM-Size?
Found the "ESP.getFreeHeap()", but I think this is something different?

my ESP8266: ESP-01 V2 / ESP-12E (NodeMCU)
ESP8266 Arduino add-on
Arduino IDE 1.6.5

- Mon Aug 31, 2015 3:10 pm #27482 Howdy there .... I think the amount of free heap space is exactly the amount of free RAM usable by your application for allocatable storage. There is probably a second concept called "the stack" which is the amount of RAM usable for storing local variables and subroutine nested return data ... but generally (opinion) the heap is the measurement of usable RAM data.

See also:

https://en.wikipedia.org/wiki/Memory_management#HEAP

Free ESP8266 book available for download here.

- Mon Aug 31, 2015 3:57 pm #27490 OK thx,

--> gets me ~45500 free "HEAP"

Thought there is only SRAM of 32k??

my ESP8266: ESP-01 V2 / ESP-12E (NodeMCU)
ESP8266 Arduino add-on
Arduino IDE 1.6.5

- Mon Aug 31, 2015 5:35 pm #27496 Aha!! Yes ... I thought there was only 64K of ram .. turns out there is a lot more. There appears to be TWO banks of RAM in the device. One is 80K in size and the other is 32K in size giving us a total of 112K. Apparently, the 32K is used for fast instruction access while the 80K is used for slower (and that is relative) data.

I wish I had more details to offer ... but sadly no.

Free ESP8266 book available for download here.