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ESP HTTPS OTA

Overview

esp_https_ota provides simplified APIs to perform firmware upgrades over HTTPS. It's an abstraction layer over existing OTA APIs.

Application Example

esp_err_t do_firmware_upgrade()
{
    esp_http_client_config_t config = {
        .url = CONFIG_FIRMWARE_UPGRADE_URL,
        .cert_pem = (char *)server_cert_pem_start,
    };
    esp_err_t ret = esp_https_ota(&config);
    if (ret == ESP_OK) {
        esp_restart();
    } else {
        return ESP_FAIL;
    }
    return ESP_OK;
}

Partial Image Download over HTTPS

To use partial image download feature, enable partial_http_download configuration in esp_https_ota_config_t. When this configuration is enabled, firmware image will be downloaded in multiple HTTP requests of specified size. Maximum content length of each request can be specified by setting max_http_request_size to required value.

This option is useful while fetching image from a service like AWS S3, where mbedTLS Rx buffer size (:ref:`CONFIG_MBEDTLS_SSL_IN_CONTENT_LEN`) can be set to lower value which is not possible without enabling this configuration.

Default value of mbedTLS Rx buffer size is set to 16K. By using partial_http_download with max_http_request_size of 4K, size of mbedTLS Rx buffer can be reduced to 4K. With this confiuration, memory saving of around 12K is expected.

Signature Verification

For additional security, signature of OTA firmware images can be verified. For that, refer :ref:`secure-ota-updates`

API Reference

.. include-build-file:: inc/esp_https_ota.inc