"Not enough heap memory"

Author	Message
matherp Guru Joined: 11/12/2012 Location: United Kingdom Posts: 11318	Posted: 08:12am 02 Apr 2026       When PSRAM is enabled there are two heap memory pools. One in main RAM and one in PSRAM. For performance reasons internal functions that use memory always only use normal RAM so in your example calling a subroutine needs memory and always gets it from the normal ram pool. Variable memory usage will first try to use normal RAM as it is faster and if not enough is available will then use PSRAM. It will automatically use PSRAM for a variable if the request for memory is more than half the size of the RAM pool (i.e. big arrays). You have created an edge case. You have lots of relatively small variables that are filling the heap in normal RAM and not triggering the condition that places them in PSRAM. Then when the system needs RAM for internal use there isn't any hence the error. I can't see an easy solution that is performant. The obvious answer would be to place variables in PSRAM if the heap in normal ram falls below a certain level. The problem with this is that calling the routine to calculate how much normal ram is left would massively slow down variable creation. This wouldn't matter too much for global variables but would be a disaster for local variables.