ESP32: 8 MB PSRAM himem?

Development Platforms
1

To access all of the ESP32’s PSRAM in newer WROVER modules with 8 MB, some special code is needed to bank-switch things around a bit, since at most 4 MB can be mapped into the ESP’s address space at any time.

It looks like Espressif has this covered with “himem” support, see: https://github.com/espressif/esp-idf/tree/master/examples/system/himem. In PlatformIO, there’s a header file called esp_himem.h which can be included.

Is himem/bank-switching supported with the current release of PlatformIO? I’m getting error messages of the form “E (131) esp_himem: Cannot allocate memory for meta info. Not initializing!”.

PS. More info on hiram is in this documentation page.

PPS. To follow up, this code:

printf("PsramSize %u\n", ESP.getPsramSize());
printf("spiram size %u\n", esp_spiram_get_size());
printf("himem free %u\n", esp_himem_get_free_size());
printf("himem phys %u\n", esp_himem_get_phys_size());
printf("himem reserved %u\n", esp_himem_reserved_area_size());

Generates this output:

PsramSize 3932108
spiram size 8388608
himem free 0
himem phys 4456448
himem reserved 262144

The one I don’t understand is “himem free”, i.e. esp_himem_get_free_size().

2

You’ve also modified your sdkconfig.h to include the modified parameters, yeah?

3

Ah, I forgot to mention that I’m using framework = arduino - does this apply?

From what I can tell, they are already enabled in ~/.platformio/packages/framework-arduinoespressif32//tools/sdk/include/config/sdkconfig.h

(I’m using latest PlatformIO, version 3.6.7 on MacOS)

4

Does the code work as expected within the latest Arduino IDE with the latest Arduino-ESP32 board version?

5

Ah, it’s been years since I last used the Arduino IDE. Updated. ESP32 installed from git. Build of test sketch works, but I get a failure running esptool (java.io.IOException: Cannot run program "/Users/jcw/Documents/Arduino/hardware/espressif/esp32/tools/esptool": error=13, Permission denied). I can’t seem to solve this quickly - even though this is off topic: could you give me a quick hint where the IDE places its compiled firmware image on MacOS? Then I can upload manually.

6

In the Arduino IDE settings, activate the verbose building checkmark and recompile, the final linker command should tell you where it placed the binary. You may also try to sudo chown -R jcw:jcw /Users/jcw/Documents/Arduino/*?

7

Thanks: chown didn’t fixi it, but yeah, forgot all about the verbose setting. Ok, looks like esptool isn’t being started up correctly - anyway, I can now upload.

No dice:

entry 0x400806a8
E (108) spiram: SPI RAM not initialized
E (108) esp_himem: Cannot allocate memory for meta info. Not initializing!
PsramSize 0
E (23) spiram: SPI RAM not initialized
spiram size 4294967295
himem free 0
E (23) spiram: SPI RAM not initialized
himem phys 4291035135
himem reserved 262144

My entire sketch is:

extern "C" {
#include <esp_spiram.h>
#include <esp_himem.h>
}

void setup() {
  printf("PsramSize %u\n", ESP.getPsramSize());
  printf("spiram size %u\n", esp_spiram_get_size());
  printf("himem free %u\n", esp_himem_get_free_size());
  printf("himem phys %u\n", esp_himem_get_phys_size());
  printf("himem reserved %u\n", esp_himem_reserved_area_size());
}

void loop() {}

Do I need to enable flags somewhere? I’ll dig a bit.

As for the esptool problem, off-topic and FWIW: the IDE is launching what looks like the directory of the tool, not the tool itself. I’m using github head.

8

Progress, removing ESP.getPsramSize() and adding esp_spiram_init():

entry 0x400806a8
E (121) spiram: SPI RAM not initialized
E (121) esp_himem: Cannot allocate memory for meta info. Not initializing!
spiram size 8388608
himem free 0
himem phys 4456448
himem reserved 262144

But as far as I can tell, it’s now the same as in platformio.

9

My wild guess is that the himem init code is running at boot time, before spiram has been initialised.

10

If it’s not able to run properly in the Arduino-IDE distributation of Arduino-ESP32, I think it’s best to open an issue at Issues · espressif/arduino-esp32 · GitHub to let the developers help you, instead of us figuring it out independently and taking longer, and then carrying the fix over to them.

1 Like
11

Ok, many thanks for your quick help - submitted: https://github.com/espressif/arduino-esp32/issues/2830.

12

Also submitted here - Banked himem (8 MB psram) support · Issue #185 · platformio/platform-espressif32 · GitHub - since the problem seems to be more involved.

1 Like