SAMD Flash Overview
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Applicable for SAMD21x18 with 256k FLASH
EFU - External Flash Update
| address | size | Description |
|---|---|---|
| 0x00000-0x01FFF | 0x2000 (8k) | Arduino Bootloader |
| 0x02000-0x05FFF | 0x3FFF (16k) | 2nd stage update bootloader, last 256 bytes (0x05F00-0x05FFF) Bootloader EEPROM |
| 0x06000-0x3DFFF | 0x38000 (224k) | Sketch |
| 0x3E000-0x3FFFF | 0x2000 (8k) | 8k virtual "flash EEPROM" |
IFU - Internal Flash Update
| address | size | Description |
|---|---|---|
| 0x00000-0x01FFF | 0x2000 (8k) | Arduino Bootloader |
| 0x02000-0x05FFF | 0x3FFF (16k) | 2nd stage update bootloader, last 256 bytes (0x05F00-0x05FFF) Bootloader EEPROM |
| 0x06000-0x21FFF | 0x1C000 (112k) | Sketch |
| 0x22000-0x3DFFF | 0x1C000 (112k) | Update |
| 0x3E000-0x3FFFF | 0x2000 (8k) | 8k virtual "flash EEPROM" |
Some additional information:
- SAMD21G18A has 256 KByte FLASH
- PAGE size is 64 Byte
- One ROW has 4 pages.
- Before one PAGE can be written, whole ROW that contains this PAGE must be erased.
=> the minimum writeble amount of data is 256 bytes (1 ROW/4 PAGES).
Example: you will write some bytes to page 1. Pages 0,2 and 3 are on the same ROW. Pages 0,2 and 3 contains already some date.
- So you have to read the data of this 3 pages to an array
- add data of page 1 to this array
- erase whole row (=pages 0,1,2,3)
- and then write whole row(=pages 0,1,2,3)