JesFs - Jo's Embedded Serial File System

for Standard (Serial) NOR-Flash

Just think of very simple things like language data: on a “very small” Embedded Device (not something “big” like an Embedded Linux, but something that can run with small batteries for years): it is commonly integrated “somewhere in the code”.
Difficult to change! But if the language data is in files, changes are easy. Same for graphics, setups, everything… It even allows to change the firmware on the Embedded Device from many different sources!

Think of Embedded Devices, that even can get their latest firmware by themselves! E.g. over WiFi, Mobile Internet, Bluetooth, UART, Radio-Link, …
Suddenly all options are open! And if you have concerns about the security: don’t worry: problem already solved, as you’ll see later..

The main problem for “very small devices” – until now – was the “File System”: everybody knows “FAT”, “NTFS”, … but have you ever thought of a file system on a small chip? Or even inside of a CPU? No problem, with the right Software. This is why I wrote

“JesFs – Jo’s Embedded Serial File System“

[Image: 4MB JesFs on 2x3 mm]

My daily work ist the IoT. Because I did not find any really practical solution, I decided to create my own one. “Robustness”, “Security” and “Small Footprint” were my design constraints.

JesFs was designed for use in the “Real World” and for use with standard Serial NOR-Flash memories, like the M25R-Series, used on nRF52840-DK, nRF52832 and the CC13xx/CC26xx Launchpads, which is available up to 16 MB, or even more…

Some Basics about JesFs:

• Ultra-Small RAM and code footprint: can be used on the smallest MCUs with only 8kByte program memory or less (like the famous MSP430-series, almost all kind of 32-Bit ARM cores (M0, M3, M4, ….)). Only 200 Bytes of RAM are sufficient!
• Completely Open Source (GPL v3) and written in Standard C.
• Works with Serial NOR-Flash from 8kByte to 16MByte (opt. up to 2GByte), but could also be used with CPU-internal NOR-Flash.
• Works hand-in-hand with the Ultra-Small JesFsBoot Secure bootloader (requires less than 8kB on standard ARM cores, including an AES-128 encryption engine for reliable Over-the-Air-Updates (“OTA”)).
• Includes optimised Wear Leveling (for maximum life of the memory).
• Very Fast Data transfer (e.g. reading files: 3.7MB/sec on nRF52840).
• A special mode was added to allow millions of write cycles, especially for data collection, event reports and journaling aplications.
• JesFs is persistent: no data loss on Power Loss or Reset.
• Designed for (almost) all situations, where NOR memories could be used (the ones where only blocks can be deleted (0->1) and only 0 written.
• Tested with: Macronix MX25Rxx, GigaDevices GD25WDxx and GD25WQxx, ...
• Strictly taylored to Ultra-Low-Power Embedded Systems
• Designed to use the advantage of an underlying RTOS, but can also be used standalone.
• Sample applications for the nRF52840/nRF52832-DK, Launchpads CC13xx/26xx, Atmel SAMD20, Windows-PC and others (Documentation PDF: JesFs.pdf)
• Easy to use with an intuitive API:

  int16_t fs_open(FS_DESC *pdesc, char* pname, uint8_t flags);
  int32_t fs_read(FS_DESC *pdesc, uint8_t *pdest, uint32_t anz);
  int16_t fs_write(FS_DESC *pdesc, uint8_t *pdata, uint32_t len);
  int16_t fs_close(FS_DESC *pdesc);
  int16_t fs_delete(FS_DESC *pdesc);
  int16_t fs_rewind(FS_DESC *pdesc);
  int16_t fs_rename(FS_DESC *pd_odesc, FS_DESC *pd_ndesc);
  uint32_t fs_get_crc32(FS_DESC *pdesc);
  int16_t fs_check_disk(void cb_printf(char *fmt, ...), uint8_t *pline, uint32_t line_size);
  
  int16_t fs_format(uint32_t f_id);
  int16_t fs_start(uint8_t mode);
  void fs_deepsleep(void);

  int16_t fs_info(FS_STAT *pstat, uint16_t fno);
  void fs_sec1970_to_date(uint32_t asecs, FS_DATE *pd);

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Changelog (JesFs_main.c)

• V1.0 CC13XX/CC26xx and Windows
• V1.5 (nRf52) nRF52840 port
• V1.51 (nRf52) nRF52840 support Deep Sleep/Wakeup (Deep Sleep with RTC active and Full RAM retention <3uA)
• V1.6 Added 'fs_disk_check()': careful Disk Check
• V1.61 (nRf52) source cosmetics and reduced default SPIM Clock to 16MHz on nRF52840 (32MHz recommended only without Softdevice)
• V1.7 (nRf52) Added Defines for u-Blox NINA-B3
• V1.8 Added Time set with '!' and UART-RX-Error
• V2.0 (nRf52) Changed UART Driver to APP_UART for Multi-Use in tb_tools
• V2.01 (nRf52) Changed to SDK17 (problem with nrf_clock() in SDK17, see docu)
• V2.02 (nRf52) Changed to SDK17.0.2 and SES 5.10b (problem with nrf_clock() in SDK17.0.2 not fixed in SDK17.0.2, see docu)
• V2.10 (nRF52) Added Support for nRF52832
• V2.20 (nRF52) Added Sample for nRF52832 (I/O Configuration for u-Blox ANNA-B112-module)
• V2.30 (nRF52) Added print of Flash ID for analysis in JesFs_main.c
• V2.54 (nRF52) Added 'tb_get_runtime()' in tb_tools.c
• V2.55 (nRF52) Changed to SDK17.1.0 and SES 5.42ab (problem with nrf_clock() in SDK17.0.2 not fixed in SDK17.0.2, see docu)
• V2.60 (nRF52) Use global Macro $SDK_ROOT
• V2.61 (SAMD20) Atmel SAMD20 contributed (kudos!)
• V2.70 added _feature supply_voltage_check();
• V2.71 all global fs_-functions check _supply_voltage_check() on entry

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Using JesFs – BlackBox-Demo

A Flight Recorder for Home Use

Many technical devices work reliable for years and years and no one cares about them. But if they fail, there is always the question: WHAT WENT WRONG?

This is, where the JesFs could become extremely useful.

Read more: BlackBox_Eval.pdf

Hardware

Some tested Serial-Flash Chips

Wide Voltage Range (1.6v-3.6V) and Ultra-Low-Power Standby:

• Macronix MX25R-Series (MX25Rxx)
• GigaDevices GD25W-Series (GD25WD80C, GD25WQ64E, ...)

Use with NRF52-CPUs:

Use with CC13xx/26xx-CPUs:

Installation (for NRF52 CPUs):

• Built with SES (V6.22a ()) and SDK 17.1.0 (: Later Versions of SES require changed project settings!!!)

• Set Macro $SDK_ROOT where to find the SDK in SES -> Tools -> Options -> Building: e.g.: "Global Macros": "SDK_ROOT=C:\nordic\nRF5_SDK_17.1.0_ddde560"

• Set Platform Macro with I/O-Pins (see tb_tools.h)

• Optionally fix Problem with nrf_clock() (see docu tb_tools_nrf52.c/.h)

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