CH32V003 Flash Memory Storage

Tired of losing those precious user config settings every time the power blinks? Fear not, you can now save them without needing an extra flash chip!

This library lets you tame the flash memory in your CH32V003 microcontroller. It's like a digital safe for your non-volatile settings, but remember, this safe has a limited number of uses (10,000 to be exact). For heavy-duty use, consider getting an external flash chip for added durability.

About CH32V003

Your trusty cheap CH32V003 microcontroller comes with a 16K flash memory, and we can set aside a portion of it to store data that pops up during runtime, like calibration values or your favorite user settings.

The catch? The flash has limited write cycles (flash endurance), and you have to do some prep work before writing your values.

But for stuff that doesn't change much, it's a perfect fit!

Get all the nitty-gritty details and usage instructions in ch32v003_flash.h.

This code utilizes the ch32v003fun project for unlocking the raw power of this microcontroller. Refer to their GitHub for installation instructions.

TL;DR

• Store tiny amounts of data in your CH32V003's main flash memory.
• During boot, call flash_set_latency() once to get things rolling.
• To modify the main flash:
  1. Unlock it with flash_unlock_main().
  2. Erase page(s) using flash_erase_page(). Sorry, no smaller erasures allowed!
  3. Program your values with flash_program_16_bits().
  4. Lock the flash using flash_lock().
• To tweak option bytes:
  1. Unlock the flash with flash_unlock().
  2. Unlock option bytes with flash_unlock_option_bytes().
  3. Write to option bytes with flash_write_option_bytes_16_bits(). This internally erases them and restores other values.
  4. Lock the flash again with flash_lock().

Need to find the right spot in your main flash for your variables? Use flash_calculate_runtime_address(n) to work it out. Provide a number of bytes from the start of the non-volatile area.

Function Cheat Sheet

Here's a quick reference for the main functions:

• flash_calculate_runtime_address(uint16_t byte_number): Calculates the runtime address for nonvolatile storage.
• flash_set_latency(): Sets the flash controller latency according to SYSTEM_CORE_CLOCK speed.
• flash_unlock(): Unlocks the main flash for altering.
• flash_unlock_option_bytes(): Unlocks the option bytes for altering.
• flash_lock(): Locks the flash after modifications.
• flash_erase_page(uint32_t start_addr): Erases a 64-bit page in flash memory.
• flash_program_16(uint32_t addr, uint16_t data): Programs 16 bits of data into flash memory.
• flash_program_2x8_bits(uint32_t addr, uint8_t byte1, uint8_t byte0): Programs two 8-bit values into flash memory.
• flash_program_float_value(uint32_t addr, float value): Programs a float value into flash memory.
• flash_read_16_bits(uint32_t addr): Reads 16 bits of data from flash memory.
• flash_read_8_bits(uint32_t addr): Reads an 8-bit value from flash memory.
• flash_read_float_value(uint32_t addr): Reads a float value from flash memory.
• flash_write_option_byte_16_bits(uint16_t data): Writes 16 bits of data to the option bytes.
• flash_write_option_byte_2x8_bits(uint8_t data1, uint8_t data0): Writes two 8-bit values to the option bytes.
• flash_read_option_byte_USER(): Reads the USER option byte from the option bytes area.
• flash_read_option_byte_RDPR(): Reads the RDPR option byte from the option bytes area.
• flash_read_option_byte_WRPR1(): Reads the WRPR1 option byte from the option bytes area.
• flash_read_option_byte_WRPR0(): Reads the WRPR0 option byte from the option bytes area.
• flash_read_option_byte_DATA1(): Reads the DATA1 option byte from the option bytes area.
• flash_read_option_byte_DATA0(): Reads the DATA0 option byte from the option bytes area.
• flash_read_option_byte_DATA_16(): Reads both DATA1 and DATA0 option bytes as a 16-bit value.

Quick Tips

• Erasing data must be done in 64-bit chunks. (ie pages)
• Don't try writing outside the main flash address space; it might turn your microcontroller into a popsicle.
• Fun fact: Option bytes store data as IIIIIIII DDDDDDDD, where D is data (byte0), and I is the inverse of data (byte1).
• To write a byte (8 bits), you need a 16-bit value (uint16_t) with the upper 16 bits (I) being the inverted pattern of D.

Meet the Creators

• recallmenot (Original code author)
• Tal G

GitHub Repository (Original Code Found Here)

Now, go ahead and have some flash-tastic fun managing your CH32V003 microcontroller's memory!