Using SPI RAM from C++ programs

Posts: 49
Joined: Tue Mar 08, 2016 5:03 am

Using SPI RAM from C++ programs

Postby markwj » Fri Jan 12, 2018 1:03 am

Any suggestions for the best way to use SPI RAM from C++ programs?

I tried setting the "SPI RAM access method" to "Make RAM allocatable using malloc() as well", and reducing "Maximum malloc() size, in bytes, to always put in internal memory" to 32 bytes, but get this crash on startup:

Code: Select all

#0  0x4008dfbc in invoke_abort () at /Users/mark/esp3o/esp-idf/components/esp32/./panic.c:139
#1  0x4008e0b2 in abort () at /Users/mark/esp3o/esp-idf/components/esp32/./panic.c:148
#2  0x4008975e in vPortCPUInitializeMutex (mux=0x3f800238) at /Users/mark/esp3o/esp-idf/components/freertos/./port.c:303
#3  0x400899fc in xQueueGenericReset (xQueue=0x3f8001e8, xNewQueue=1) at /Users/mark/esp3o/esp-idf/components/freertos/./queue.c:270
#4  0x40089a78 in prvInitialiseNewQueue (uxQueueLength=32, uxItemSize=48, pucQueueStorage=0x3f800240 '\376' <repeats 200 times>..., ucQueueType=0 '\000', pxNewQueue=0x3f8001e8)
    at /Users/mark/esp3o/esp-idf/components/freertos/./queue.c:441
#5  0x40089ac9 in xQueueGenericCreate (uxQueueLength=32, uxItemSize=48, ucQueueType=0 '\000') at /Users/mark/esp3o/esp-idf/components/freertos/./queue.c:408
#6  0x40162490 in esp_event_loop_init (cb=<optimized out>, ctx=0x3ffb4980 <MyEvents>) at /Users/mark/esp3o/esp-idf/components/esp32/./event_loop.c:103

(gdb) frame 2
#2  0x4008975e in vPortCPUInitializeMutex (mux=0x3f800238) at /Users/mark/esp3o/esp-idf/components/freertos/./port.c:303
303       configASSERT(esp_ptr_internal((const void *) mux));

Presumably that is esp_event_loop_init trying to create a FreeRTOS queue, and then objecting because it is not in internal RAM? It seems that the ESP IDF framework is not fully working with SPI RAM yet (due to inherent limitations). It would be better if the memory to be allocated must be internal, it is specifically allocated as internal (rather than just rely on a generic malloc). I understand that this will take some time to work the kinks out.

Anyway, for my application, it would be fine if the C++ new() operator allocated from SPI RAM. If I had a case where I needed that data for a flash write, or DMA access, I'd add a specific malloc to allocate from internal RAM.

Has anybody here done this, or worked with this? I know that the template allocators in C++ have some options for things like this, but none seem to have been provided for SPI RAM in the ESP IDF framework.

Posts: 1368
Joined: Thu Nov 26, 2015 4:08 am

Re: Using SPI RAM from C++ programs

Postby ESP_Sprite » Fri Jan 12, 2018 6:53 am

There's a bug we're working on where a structure containing a spinlock can sometimes be allocated in SPI RAM, and as such will not work correctly. We're at the moment working on a solution for that; a fix should appear in esp-idf master soon.

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