Bootloader for mimrxt MicroPython port
The bootloader must be programed into RT10XX qspi Flash (or Hyperflash, not tested) using one of the usual flashing ways.
Once loaded, it enables loading the firmware into flassh over the CDC/ACM port using the provided Mflash.py program loader, written in Python and capable of running any Linux or Windows machine (probably also on OSX, not yet tested).
Bootloader itself occupies the first 64MB of flash, the rest can be used for user firmware(s).
The firmware must be linked at start address equal or higher than 0x60010000.
Main features:
- works on any i.MX RT series MCU (tested with RT1052 and RT1062)
- capable of loading one of two firmwares form Flash, ideal for OTA program upgrade (the new version can be loaded from application itself)
- if valid application would start, the bootloader can be entered by pressing the user button on board
- LED indication of operation state
- very secure, two copies of the boot configuratin sectors (main and backup) are provided, if the main is corrupted it is restored from backup
- the firmware (user application) is protected and verified on boot by 32-byte SHA256 hash
- very fast communication with the loader program (~500 KB/sec),
Flash program opperation is, of course, slower and depends on how much sectors must be erased - this bootloader was build for use with MicroPython firmwares, but any firmware can be used, as long as it was correctly linked for start address of
0x60010000or higher - provided (Python) loader program features:
- programming the firmware to the specific Flash address (taken from the firmware file IVT section)
- reading any Flash area into file
- erasing any flash area
- getting the information about boot configuration
- bootloader does not permit accidental programming of its own Flash area
- works well both on Linux and Windows, (pyserial module must be installed)
Boot loader boot sector structure:
| Offset | Size | Name | Description |
|---|---|---|---|
| 0 | 16 | bootSectID | string ID: i.MXRT10XX_boot |
| 16 | 60 | app1ConfigRecord | Application #1 config record |
| 76 | 60 | app2ConfigRecord | Application #2 config record |
| 136 | 4 | bootSectCRC32 | Boot sector CRC32 calculated over the first 136 bytes |
Application config record structure:
| Offset | Size | Name | Description |
|---|---|---|---|
| 0 | 16 | appName | application name, NULL terminated string |
| 16 | 4 | appFlashAddress | application address in Flash (min addr 0x600100000) |
| 20 | 4 | appSize | application size, 24-bil; upper 8-bits are flags Application size range is 0x10000 - 0x200000 (64KB - 2MB) |
| 24 | 4 | appTimestamp | application timestamp written by Loader |
| 28 | 32 | appSHA256 | application's SHA256 hash calculated over appSize bytes from appFlashAddress The check must pass for application to be started |
Bits 24-31 of the appSize field are used as application flags:
| Bit | Comment |
|---|---|
24 |
Active flag, if set the application will be loaded and executed. If multiple entries have active flag set, the first one will be loaded and executed. If no application has active flag set, the applications will be tested for valid address, size and SHA256 hash an the first one which passes will be started. |
25 |
Not used, reserved for future use |
26 |
Not used, reserved for future use |
27 |
Not used, reserved for future use |
28 |
Not used, reserved for future use |
29 |
Not used, reserved for future use |
30 |
Not used, reserved for future use |
31 |
Not used, reserved for future use |
Notes:
The bootloader was developed and compiled with Keil (µVision® IDE).
Currently I don'have time to transfer it to gcc/makefile environment.
If anyone is interested in doing it, the Pull request is welcomed.
Prebuilt firmwares are available in the firmwares directory.
More information will be added soon...