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→Bootloader Design
Commands sent to the bootloader look as follows:
<pre>+------+------+------+ ... +------+------+------+------+
| 0x00 | Encrypted Block (16 Bytes) | CRC-16 |
+------+------+------+ ... +------+------+------+------+</pre>
The CRC uses the 16-bit CRC-CCITT polynomial (0x1021). The LSB of the calculated CRC-16 is sent first, followed by the MSB. The bootloader responds with a single byte indicating if the CRC-16 was OK or not:
<pre> +------+</pre><blockquote><dl><dt>CRC-OK: | 0xA1 |</dt><dd><p> +------+</p><p> +------+</p></dd><dt>CRC Failed: | 0xA4 |</dt><dd><p> +------+</p></dd></dlpre></blockquote>
==== Encrypted Block ====