[SAMR21 new gameplay] 31. Using NVM storage

dcexpert

[SAMR21 new gameplay] 31. Using NVM storage [Copy link]

 

In SAMR21, part of the flash space can be used to simulate EEPROM, which is called NVM (Non-Volatile Memory). Using EEPROM is simpler than flash, and bytes can be read and written directly without the need for page management like flash.

In the current version of CircuitPython, 256 bytes are allocated as NVM. The use of NVM is very simple. You only need to reference nvm through the microcontroller module. As shown below:

>>> import microcontroller
>>> from microcontroller import nvm
>>> nvm
<ByteArray>
>>> len(nvm)
256
>>> nvm[0]
255
>>> nvm[0]=5
>>> 

nvm is a bytearray array with a size of 256 bytes, which can be read and written byte by byte. The default data is 255 (0xFF). After writing data, the NVM content of the chip will be automatically modified and will not be lost after power failure. This content is originally created by dcexpert

, a user of EEWORLD forum. If you need to reprint or use it for commercial purposes, you must obtain the author's consent and indicate the source

dcexpert

In circuitpython, the NVM size set for different chips is also different. Because the flash of SAMR21/D21 is small, only 256KB, only 256 bytes of NVM are set. On the 512KB SAMD51, the NVM size is 8192.

白丁

I thought it was nvme from the title

dcexpert

Bai Ding posted on 2019-10-17 20:33 I thought it was nvme from the title