STM32F1 Flash Memory Module

This is a module (STM32F1Flash (About Modules)) for reading and writing internal flash memory on the STM32F103RC chip in the Espruino Board.

THIS IS DEPRECATED - There is now built-in support for writing flash memory of all STM32 boards, available via the Flash module


Flash memory contains Espruino, your saved program, and the bootloader - and it's almost all used. Incorrect use of this module could stop your Espruino board from working, so make sure you know what you're doing!


Figuring out what memory is free

process.memory() returns information on the addresses of various things on the device. For instance you can see how much spare memory there is by calling process.memory().flash_code_start - process.memory().flash_binary_end. To find the first page that you can safely erase, you can type:


It's also good practice to check if there's anything in the page of flash. If it's all 0xFF (4 bytes of 0xFF is 0xFFFFFFFF, which is bitwise equivalent to -1) then you're safe to overwrite it:

function isPageSafe(addr) {
  for (var i=addr;i<addr+2048;i+=4)
    if (peek32(i)^-1) return false;
  return true;

// returns true - it's all fine

isPageSafe(((process.memory().flash_binary_end+2047)&~2047) - 2048)
// returns false - don't use this address!
var adr = 0x0803E000;
var f = require("STM32F1Flash");
console.log(; // probably FFFFFFFF
f.unlock(); // unlock flash memory - allows us to do bad things...
f.erase(adr); // erase 2048 bytes from 0x0803E000
console.log(; // now definitely FFFFFFFF
f.write(adr,0xCAFEBABE); // write a 32 bit word
console.log(; // now CAFEBABE

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