ESP-IDF C5 - Assign. 2.1

To perform OTA updates, the device needs a partition table with at least two app partitions. In this assignment we will select and flash an appropriate partition table.

Assignment steps

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1. Check the current partition table.
2. Change it to a partition table scheme that supports OTA.
3. Check the new partition table.

Check the current partition table

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To check the partition table currently loaded on your module, read it back from flash and convert it to a readable format.

1. Read the flash and dump the partition table into a .bin file using esptool.py:

   esptool.py -p <YOUR-PORT> read_flash 0x8000 0x1000 partition_table.bin

   <YOUR-PORT> is the same port you use to flash the device (e.g. /dev/tty.usbmodem1131101 or COM25).

   This creates a partition_table.bin file containing the raw partition table.

2. Convert the partition_table.bin file to a readable format using gen_esp32part.py:

   python $IDF_PATH/components/partition_table/gen_esp32part.py partition_table.bin

   You get this output:

   Parsing binary partition input...
   Verifying table...
   # ESP-IDF Partition Table
   # Name, Type, SubType, Offset, Size, Flags
   nvs,data,nvs,0x9000,24K,
   phy_init,data,phy,0xf000,4K,
   factory,app,factory,0x10000,1M,
   coredump,data,coredump,0x110000,64K,

   This table has a single factory app partition, so it does not support OTA updates.

Change the partition table

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Switch to the default partition table scheme that includes two OTA app partitions, then increase the flash size so both app partitions fit.

1. Open menuconfig (> ESP-IDF: SDK Configuration Editor (menuconfig)) and go to Partition Table → Factory app, two OTA definitions.

   This replaces the single factory app partition with two OTA app partitions (ota_0 and ota_1) and adds the otadata partition used to track which one is active.

2. In the same menuconfig window, go to Serial Flasher Config → Flash Size → 4MB.

   Two 1 MB OTA app partitions no longer fit in the default 2 MB flash size, so this step is required for the new partition table to fit.

Check the new partition table

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Repeat the read and convert steps to confirm the partition table changed.

1. Read the flash again:

   esptool.py -p <YOUR-PORT> read_flash 0x8000 0x1000 partition_table.bin

2. Convert it to a readable format:

   python $IDF_PATH/components/partition_table/gen_esp32part.py partition_table.bin

   You now get:

   Parsing binary partition input...
   Verifying table...
   # ESP-IDF Partition Table
   # Name, Type, SubType, Offset, Size, Flags
   nvs,data,nvs,0x9000,16K,
   otadata,data,ota,0xd000,8K,
   phy_init,data,phy,0xf000,4K,
   factory,app,factory,0x10000,1M,
   ota_0,app,ota_0,0x110000,1M,
   ota_1,app,ota_1,0x210000,1M,

   The table now includes the otadata partition and two app partitions, ota_0 and ota_1, confirming the switch to an OTA-capable scheme.

Conclusion

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In this assignment, you changed the partition table from Single factory app, no OTA to Factory app, two OTA definitions. Both partition table schemes are default options provided by ESP-IDF. In the next assignment, you will create a custom partition table.

Next step

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Next assignment → Assignment 2.2

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