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technoblogy / ulisp-esp

A version of the Lisp programming language for ESP32-based boards.
MIT License
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ESP32 Arduino core gives less available RAM on ESP32-S2 #77

Closed technoblogy closed 3 months ago

technoblogy commented 1 year ago

I tested the latest release of uLisp on an ESP32-S2 board (Adafruit ESP32-S2 Feather) with the current Arduino core, 2.0.9, and found I have over 8Kbytes less available RAM than under the previous core I tested, 2.0.5.

This doesn't seem to happen with ESP32 boards (eg Adafruit ESP32 Feather).

In ESP uLisp release 4.4d I've therefore reduced the amount of Lisp workspace on the ESP32-S2 boards from 9216 objects to 8160 objects. Otherwise compilation fails with the error:

error: ld returned 1 exit status

I've tried to track down what's causing this, but without success. I suspect it may be the Wi-Fi libraries.

Can anyone can shed any light on this?

dragoncoder047 commented 1 year ago

I think it may be the USB interface, not Wifi, because the S2 does USB-to-serial conversion by itself, whereas the regular ESP32 has to use a external converter.

technoblogy commented 1 year ago

Interesting suggestion. Actually, there is an ESP32-S2 board with an external converter that would enable me to test this theory:

http://www.ulisp.com/show?3TQF#esp32-s2-saola-1

technoblogy commented 1 year ago

You're right! The Espressif ESP32-S2 Dev board includes a CP2102N USB to Serial converter used by default, or you can choose the native USB CDC.

With the hardware USB converter I can get 9216 objects of workspace, whereas with the native USB CDC I can only get 8160 objects, over 8Kbytes less.

However, so far I haven't been able to make a minimal reproducible example to demonstrate it.