I’ve managed to build MicroPython 1.19.1 with ESP-IDF v4.3.3 with PSRAM enabled. The screen capture above shows the free memory (the free heap, actually) in megabytes. The ESP32-S3-DevKitC-1-N8R8 has 8 MB of flash and 8 MB of external PSRAM, of which only half of that is shown. That’s because MicroPython only shows half of it in its environment. The build date is back on 16 December. The IDF version is 4.4.3, which is the last major version before 5.0 was released. I’m glad I was able to achieve this with 4.4.3 as there’s going to have to be some major changes to MicroPython 1.19.1 because of breaking changes to ESP-IDF 5.0.

The file to edit is micropython/ports/esp32/ boards/GENERIC_S3_SPIRAM/sdkconfig.board, which is listed below. The lines I added are highlighted in green and start at line 14. I found those lines by using idf.py menuconfig with one of my other ESP-IDF projects and enabling SPIRAM/PSRAM on a specific ESP32-S3 development board. That development board has 8 MB FLASH and 8 MB PSRAM. I then opened an editor with the configuration file modified by idf.py and a second window with the same configuration file in the MicroPython port board and copied from the modified configuration to the port board configuration file. Once the copy was finished the changes were saved and I moved to micropython/ports/esp32 and executed make BOARD=GENERIC_S3_SPIRAM, then flashed the development board with the product of make. After that I used idf.py -p /dev/ttyUSB0 monitor (because that’s the port my ESP32-S3 development board was connected to) and I was able to run the REPL without issue. I was also able to develop on the board with Thonny, again without any issue.

I’m so satisfied to have found this because every other explanation for how to make this work I found via searches did not work, or worked with a very old beta of ESP-IDF and involved too many file changes. This change only required modification of one file, and then a make.

CONFIG_FLASHMODE_QIO=yCONFIG_ESPTOOLPY_FLASHFREQ_80M=yCONFIG_ESPTOOLPY_FLASHSIZE_DETECT=yCONFIG_ESPTOOLPY_AFTER_NORESET=yCONFIG_SPIRAM_MEMTEST=CONFIG_ESPTOOLPY_FLASHSIZE_4MB=CONFIG_ESPTOOLPY_FLASHSIZE_8MB=yCONFIG_ESPTOOLPY_FLASHSIZE_16MB=CONFIG_PARTITION_TABLE_CUSTOM=yCONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions-8MiB.csv"## START OF ADDED CONFIGURATIONS FOR PSRAM ENABLEMENT#CONFIG_SOC_PSRAM_DMA_CAPABLE=yCONFIG_SOC_GDMA_SUPPORT_PSRAM=yCONFIG_SOC_GDMA_PSRAM_MIN_ALIGN=16## ESP PSRAM#CONFIG_SPIRAM=y## SPI RAM config## CONFIG_SPIRAM_MODE_QUAD is not setCONFIG_SPIRAM_MODE_OCT=yCONFIG_SPIRAM_TYPE_AUTO=y# CONFIG_SPIRAM_TYPE_ESPPSRAM64 is not setCONFIG_SPIRAM_ALLOW_STACK_EXTERNAL_MEMORY=y## PSRAM Clock and CS IO for ESP32S3#CONFIG_DEFAULT_PSRAM_CLK_IO=30CONFIG_DEFAULT_PSRAM_CS_IO=26# end of PSRAM Clock and CS IO for ESP32S3# CONFIG_SPIRAM_FETCH_INSTRUCTIONS is not set# CONFIG_SPIRAM_RODATA is not set# CONFIG_SPIRAM_SPEED_80M is not setCONFIG_SPIRAM_SPEED_40M=yCONFIG_SPIRAM_SPEED=40CONFIG_SPIRAM_BOOT_INIT=y# CONFIG_SPIRAM_IGNORE_NOTFOUND is not set# CONFIG_SPIRAM_USE_MEMMAP is not set# CONFIG_SPIRAM_USE_CAPS_ALLOC is not setCONFIG_SPIRAM_USE_MALLOC=yCONFIG_SPIRAM_MEMTEST=yCONFIG_SPIRAM_MALLOC_ALWAYSINTERNAL=16384# CONFIG_SPIRAM_TRY_ALLOCATE_WIFI_LWIP is not setCONFIG_SPIRAM_MALLOC_RESERVE_INTERNAL=32768# CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY is not set# CONFIG_SPIRAM_ECC_ENABLE is not set# end of SPI RAM config# end of ESP PSRAM