Data Format - Byte Ordering - Silicon Laboratories EFR32xG14 Wireless Gecko Reference Manual

30.3.3 Data Format - Byte Ordering

All cryptographic data is handled following the big-endian format (AES standard). The first byte (lowest address) of the data is the Most
Significant Byte (MSB). However, the bus interfaces on the core use little endian format for internal byte ordering within a 32-bit word.
The Least Significant Byte (LSB) within a word is stored at the lowest address.
For example, a 128-bit block 0x00112233445566778899AABBCCDDEEFF is read from the FIFO in the following order:
Word 1 = 0x33221100
Word 2 = 0x77665544
Word 3 = 0xBBAA9988
Word 4 = 0xFFDDEECC
This is important to note when checking the conditioning function for validity. The KEY registers also follow this standard, with KEY0
holding the MSB of a 128-bit value and KEY3 holding the LSB.
30.3.4 TRNG Usage
It is highly recommended to use the software libraries provided by Silicon Labs to access the TRNG module. The information in the
following sections are reference for users who choose to write their own low-level software drivers.
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TRNG - True Random Number Generator
Reference Manual
Rev. 1.1 | 1013