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Memory Map

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tommie edited this page Nov 15, 2014 · 26 revisions

This page describes the physical memory layout of the ESP8266 family.

Reset Vector

The reset vector is 40000000h or 50000000h, which maps to internal ROM.

Memory Layout

Address Name Size Type R/W Description
3FF00000h dport0 16 I/O RW? Memory-mapped I/O.
3FF40000h drom0 <40000h ROM R? Unconfirmed. Known from the XT2000 memory map.
3FF80000h dram1 <40000h RAM RW Unconfirmed. Known from the XT2000 memory map.
3FFE8000h dram0 80k RAM RW User data RAM. Available to applications.
40000000h brom? 64k ROM RW? Internal ROM. May be writable somehow, but details unknown.
40100000h iram1 32k RAM RW Instruction RAM. Shadowed version of 40200000h.
40200000h irom0 <100000h ROM RW SPI Flash ROM?
40211000h irom0 <100000h ROM RW User application, slot 1.
40240000h irom0 <100000h ROM RW User application start.
40251000h irom0 <100000h ROM RW User application, slot 2.
50000000h srom <1000000h ROM R? Unconfirmed. Known from the XT2000 memory map.
60000000h sram <4000000h RAM RW Unconfirmed. Known from the XT2000 memory map.
70000000h iocch <E000000h I/O RW? Cached I/O. Unconfirmed. Known from the XT2000 memory map.
80000000h rambp <10000000h RAM RW Uncached RAM. Unconfirmed. Known from the XT2000 memory map.
90000000h iobp <E000000h I/O RW? Uncached I/O. Unconfirmed. Known from the XT2000 memory map.

SPI Flash ROM Layout (without OTA upgrades)

This is for ESP IoT SDK version 0.8 and above.

Address Size Name Description
00000h 248k app.v6.flash.bin User application
3E000h 8k master_device_key.bin OTA device key
40000h 240k app.v6.irom0text.bin SDK libraries
7C000h 8k esp_init_data_default.bin Default configuration
7E000h 8k blank.bin Filled with FFh. May be WiFi configuration.

SPI Flash ROM Layout (with OTA upgrades)

This is for ESP IoT SDK version 0.8 and above, supporting OTA upgrades.

Address Size Name Description
00000h 4k boot.bin Bootloader
01000h 64k app.v6.flash1.bin User application, slot 1
11000h 180k app.v6.irom0text1.bin SDK libraries, slot 1
3E000h 8k master_device_key.bin OTA device key
40000h 4k Unused
41000h 64k app.v6.flash1.bin User application, slot 2
51000h 180k app.v6.irom0text1.bin SDK libraries, slot 2
7E000h 8k blank.bin Filled with FFh. May be WiFi configuration.

Exception Vectors

Unconfirmed. From the XT2000 memory map.

Address Name
40000000h Reset
40000010h DebugException
40000020h NMIException
40000030h KernelException
40000050h UserException
40000070h DoubleException

References

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