esp32_ota
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esp32_ota [2024/03/19 18:45] sausage Troubleshooter |
esp32_ota [2025/02/02 21:16] (current) sausage CRC checksum details |
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| Over The Air (OTA) provides a way to send firmware to your ESP32 board in the field without the need for a cable and physical access to the device. | Over The Air (OTA) provides a way to send firmware to your ESP32 board in the field without the need for a cable and physical access to the device. | ||
| - | The purpose of this article is manually step through the various stages of the OTA process and illustrate the state of the ESP32 at each stage. | + | The purpose of this article is to manually step through the various stages of the OTA process and illustrate the state of the ESP32 at each stage. |
| Together we will set up a number of firmwares suitable for testing on different partitions in flash memory. | Together we will set up a number of firmwares suitable for testing on different partitions in flash memory. | ||
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| </code> | </code> | ||
| - | Ignoring the ''nvs'' and ''phy_init'' partitions, we have the default ''factory'' partition that starts at 0x10000. Ironically, the list of partitions doesn't list the bootloader partition at 0x1000 or the partition that the partition table itself is stored on (at 0x8000). | + | Ignoring the ''nvs'' and ''phy_init'' partitions, we have the default ''factory'' partition that starts at 0x10000. Ironically, the list of partitions doesn't list the bootloader partition at 0x1000 or the partition that the partition table itself is stored (at 0x8000). |
| ===== OTA partitions ===== | ===== OTA partitions ===== | ||
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| - 4blinks.bin | - 4blinks.bin | ||
| - | Now the ''idf.py flash'' command is only able to flash the default project firmware to the ''factory'' partition. So we'll need to switch to a different command to flash a named firmware to a particular partition. | + | Note that the ''idf.py flash'' command is only able to flash the default project firmware to the ''factory'' partition. So we'll need to switch to a different command to flash a named firmware to a particular partition. |
| Take another look at our partitions table. | Take another look at our partitions table. | ||
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| </code> | </code> | ||
| - | Interesting. On the left is ''ota_0''. It has a boot sequence of ''01'' and a CRC check (not covered in this article). This partition will boot each time the ESP32 is reset. On the right is ''ota_1'', and there is nothing here to indicate if it should boot. | + | Interesting. On the left is ''ota_0''. It has a boot sequence of ''01'' and a CRC checksum (keep a note of this, we will come back to this). This partition will boot each time the ESP32 is reset. On the right is ''ota_1'', and there is nothing here to indicate if it should boot. |
| We can also verify the ''otadata'' partition and take a closer look at what is stored there now. | We can also verify the ''otadata'' partition and take a closer look at what is stored there now. | ||
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| ''9A 98 43 47'' is the firmware checksum. | ''9A 98 43 47'' is the firmware checksum. | ||
| + | |||
| + | Remember the CRC checksum in ''ota_0''? | ||
| + | |||
| + | ''0x4743989a''. This is how you can confirm which firmware is running. | ||
| Let's switch to booting the firmware on ''ota_1'': | Let's switch to booting the firmware on ''ota_1'': | ||
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| In our case, the second sector has a new entry, the ''02'' sequence. This is for the firmware on ''ota_1''. ''02'' is greater than ''01'' so this is the firmware selected for boot by the bootloader. | In our case, the second sector has a new entry, the ''02'' sequence. This is for the firmware on ''ota_1''. ''02'' is greater than ''01'' so this is the firmware selected for boot by the bootloader. | ||
| + | |||
| + | Again we can inspect the checksum: ''0x55f63774'' is ''74 37 F6 55''. | ||
| How an OTA partition is determined from sequence numbers in the otadata partition is not explained in the documentation, but is explained in the code. You can see it here: https://github.com/pycom/esp-idf-2.0/blob/master/components/app_update/esp_ota_ops.c#L297 | How an OTA partition is determined from sequence numbers in the otadata partition is not explained in the documentation, but is explained in the code. You can see it here: https://github.com/pycom/esp-idf-2.0/blob/master/components/app_update/esp_ota_ops.c#L297 | ||
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| All our firmwares failed to run the ''esp_ota_mark_app_valid_cancel_rollback()'' to mark the ''otadata'' as valid. So in each case, they have become aborted and rolled back to the previously known good firmware. | All our firmwares failed to run the ''esp_ota_mark_app_valid_cancel_rollback()'' to mark the ''otadata'' as valid. So in each case, they have become aborted and rolled back to the previously known good firmware. | ||
| - | The ''factory'' firmware isn't controlled by the ''otadata'', the rollback process or OTA at all. | + | The ''factory'' firmware isn't affected by ''otadata'', or the rollback process, or OTA at all. |
| To finish up, let's take a last look at the raw otadata: | To finish up, let's take a last look at the raw otadata: | ||
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| ===== Thank yous ===== | ===== Thank yous ===== | ||
| - | Many thanks to boarchuz and craig from the [[https://discord.gg/wwK29JJV|Espressif MCUs]] discord server for their advice on details in this article. | + | Many thanks to boarchuz and craig from the [[https://discord.gg/wwK29JJV|Espressif MCUs]] discord server for their assistance with this article. |
esp32_ota.1710873931.txt.gz ยท Last modified: 2024/03/19 18:45 by sausage
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