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Memory Map

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tommie edited this page Nov 17, 2014 · 26 revisions

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

Reset Vector

The reset vector is 40000080h, which maps to internal ROM.

Memory Layout

Address Name Size Type R/W Description
00000000h Exc Causes fault when reading.
20000000h No Unmapped, repeated pattern of 00 80 00 00.
3FF00000h dport0 1000h I/O RW? Memory-mapped I/O, repeated every 100h.
3FF10000h No Unmapped, zeroes.
3FF20000h ? ? RW? Unidentified data.
3FF30000h No Unmapped, zeroes.
3FFC0000h ? 20000h ? RW? uint32 mapping to the address it is located at. What is this?
3FFE0000h No Unmapped, zeroes.
3FFE8000h dram0 14000h RAM RW User data RAM. Available to applications.
3FFFC000h 4000h RAM ETS system data RAM.
40000000h brom? 10000h ROM RW? Internal ROM. May be writable somehow, but details unknown.
40010000h No Unmapped, zeroes.
40100000h iram1 10000h RAM RW Instruction RAM. Used by bootloader to load SPI Flash <40000h.
40110000h ? Zeroes.
40140000h ? Repeated pattern of 59 31 d8 ec.
40200000h ? Zeroes. SPI Flash loads/is mapped here.
40300000h ? Unmapped, repeated pattern of 00 80 00 00.
60000000h ? 1000h I/O RW? I/O
60001000h ? 800h ? RW? I/O
60001800h ? 800h ? RW? Mapped to 60001000h?
60002000h Exc Causes fault when reading.
70000000h 90000000h No Unmapped, repeated pattern of 00 80 00 00.

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

Address Name
40000010h DebugException
40000020h NMIException
40000030h KernelException
40000050h UserException
40000070h DoubleException
40000080h Reset

References

  1. Toolchain
  2. Building
  3. Uploading
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