How to detect and confirm the actual size of the RP2040 onboard SPI FlashRAM?

yang_alex

How to detect and confirm the actual size of the RP2040 onboard SPI FlashRAM? [Copy link]

We know that the RP2040 onboard SPI FlashRAM supports up to 16MByte (128Mbit). So, how can we know the real size of a RP2040 onboard SPI FlashRAM?

1. The device model is erased and cannot be seen directly.

2. I don’t want to solder the SPI FlashRAM off the board and read it with a programmer.

3. I tried to insert the USB drive into the PC, write a file larger than 18MByte in the form of a USB flash drive, close the folder and reopen it (without plugging in or unplugging the RP2040 board), and the file larger than 18MByte is readable normally. But if I eject the USB drive and then reinsert it into the PC and enter the USB flash drive form, the file disappears. I guess it is not actually written into the USB flash drive, but stored in the cache. So this method of detecting the actual size of the RP2040 onboard SPI FlashRAM does not work.

I'd like to see if anyone has a good way to easily check the actual size of the RP2040 onboard SPI FlashRAM.

dcexpert

If you are using the UF2 bootloader, writing a file is actually updating the program. If the file format is incorrect, it will not be updated. The file you read is actually cached by the computer.

If you use MicroPython, you can check the size of Flash and RAM by the following method (this method is universal and supported by most MicroPython versions, but please note that the system will occupy some space, so the actual value is smaller than the actual physical size):

First enter REPL and enter the following command:

flash

import os

d = os.statvfs('/flash')

# File size

d[0]*d[2]

# Remaining space size

d[0]*d[3]

ram

import gc

gc.mem_free()+gc.mem_alloc()

yang_alex

Thank you! What is the unit of d[0]*d[3]? Byte?

yang_alex

In addition, is this checking the size of the onboard SPI Flash?

yang_alex

dcexpert posted on 2023-1-1 14:13 If it is under UF2 bootloader, writing a file is actually updating the program. If the file format is incorrect, it will not be updated. The file you read is actually calculating...

Is the size obtained by d[0]*d[3] the actual size of the SPI Flash or the size configured in the code?

yang_alex

dcexpert posted on 2023-1-1 14:13 If it is under UF2 bootloader, writing a file is actually updating the program. If the file format is incorrect, it will not be updated. The file you read is actually calculating...

I think this size is the size of the SPI Flash selected when the code is compiled into the firmware. It is not the actual size of the SPI Flash.

So the question is: in the MicroPython world, how does it manage the SPI Flash space? Can I read and write the space at a specified physical address?

dcexpert

yang_alex published on 2023-1-1 22:28

It is indeed a parameter set at compile time, and then can be read in a certain way.

Micropython generally does not directly read the physical address space, but directly creates, writes, and reads files through files, which is much simpler than sectors. However, you need to be particularly careful when writing files, because the flash write speed is relatively slow. If there is a large amount of writing, it is easy to conflict with other functions and cause some problems.