ESP32 Partition Size Calculations#
How to calculate and configure ESP32 flash partitions for OTA updates, NVS and SPIFFS. A practical walkthrough from an embedded engineering consultancy.
ESP32 modules come in various flash memory sizes, the most common being 4MB, but 8MB & 16MB modules are available. The flash memory needs to be partitioned depending on requirements & constraints.
The requirements include:
- Is over the air (OTA) updating feature required?
- Is the main application (app) substantial in size?
- Is a basic file system (e.g. SPIFFS) required?
Constraints include:
- Offset must be a multiple of 4 KB / 0x1000
- Type
apppartitions have to be placed at offsets aligned to 0x10000 (64 K) - The bootloader & partition table occupy the region 0x0 to 0x9000
Some ‘standard’ partition schemes for the 4MB module are:
“Single factory app, no OTA”
# ESP-IDF Partition Table
# Name, Type, SubType, Offset, Size, Flags
nvs, data, nvs, 0x9000, 0x6000,
phy_init, data, phy, 0xf000, 0x1000,
factory, app, factory, 0x10000, 1M,“Factory app, two OTA definitions” configuration
# ESP-IDF Partition Table
# Name, Type, SubType, Offset, Size, Flags
nvs, data, nvs, 0x9000, 0x4000,
otadata, data, ota, 0xd000, 0x2000,
phy_init, data, phy, 0xf000, 0x1000,
factory, app, factory, 0x10000, 1M,
ota_0, app, ota_0, 0x110000, 1M,
ota_1, app, ota_1, 0x210000, 1M,Tables can be further complicated with multiple OTA partitions.
Creating your own table to support a different layout or different sized module can require some tedious calculations. To save time, use the following tool — just input the module size & required SPIFFS size and the table will be generated for you:
Download ESP32 Partition Generator
If you need help with production-grade ESP32 firmware or partitioning, take a look at our Software Development services.