a correction to: adafruit esp32 feather v2

In the last post I wrote that you could flash this Adafruit Feather with a version of MicroPython. Unfortunately it did not enable the use of the board’s SPIRAM. The specifications for this board declares that it has 4MiB of non-volatile (FLASH) and 2MiB of RAM (SPIRAM). When I went to check for the amount of free RAM it was far lower than I expected. That’s when I realized I’d use the wrong MicroPython image to flash the Feather. The correct link is: https://micropython.org/download/esp32spiram/ .

One way to test that you are seeing all the RAM is by adding two lines to the blink code, starting at line 13.

import esp
print("Flash size {} in bytes".format(esp.flash_size()))
import gc
print("Memory free {} in bytes.".format(gc.mem_free()))

When the code executes you’ll see the following (I’m working with Thonny, and this is in Thonny’s shell):

MPY: soft reboot
esp32, esp32, 1.18.0, v1.18 on 2022-01-17, ESP32 module (spiram) with ESP32
MicroPython-1.18.0-xtensa-IDFv4.2.2-with-newlib3.0.0
Flash size 4194304 in bytes
Memory free 2046144 in bytes.

Note the second line that contains “…ESP32 module (spiram)…”, and the last line that shows 2MiB of RAM memory.