How can I write to SiPy flash memory?

[apsolar]

I need persistent storage for my application and intend to use the internal flash memory. The spec sheet says that there is 4MB flash but I can't find any documentation for using the flash. We are not designing another pcb and intend to just use the sipy board with a power supply for a demo. Without having the ability to use onboard flash memory, the application isnt much use when the power resets which would happen periodically.

[apsolar]

more info about my Sipy
rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff9010,len:12
ho 0 tail 12 room 4
load:0x3fff9020,len:388
load:0x40078000,len:11584
load:0x4009fb00,len:848
entry 0x4009fc9c
MicroPython v1.8.6-724-g2b9ed601 on 2017-07-28; SiPy with ESP32
Type "help()" for more information.

import os
os.uname()
(sysname='SiPy', nodename='SiPy', release='1.7.8.b1', version='v1.8.6-724-g2b9ed601 on 2017-07-28', machine='SiPy with ESP32', sigfox='1.0.
1')

[jmarcelino]

You can write files to the onboard /flash filesystem, there's about 512Kb available

(the stated 4MB includes the space taken up by two copies of MicroPython and some system storage area)

See this existing topic on how to read/write to files:

https://forum.pycom.io/topic/1610/nonvalatile-storage-on-wipy

[apsolar]

@jmarcelino Thank you for sharing this. To add to this question, are there code example of we can persist an array of structs to the file system? I have a clear idea of how I want to implement a simple persistent database but I cant find micropython examples of doing so. The btree library would have been great but I realised I couldnt use it in this version of the port.