We are evaluating if we can use the STM32 to interface to existing devices. The critical fator is the expected endianness of the data. I have seen no reference in the docs if this can be set, so I have provided an example message and would like to know if this can correctly interpreted by the STM.
The following sequence defines the values of bits 'in the air' as recorded on an oscilloscope. The most left bit is the first bit transmitted.
10101010 10101010 10101010 10101010 These are the 4 preamble bytes. Byte value is 0x55 with LSB
of each byte transmitted first
00110011 01010101 00110011 01010101 These are the 4 Sync bytes 0xCC 0xAA 0xCC 0xAA in sequence
of transmission, with LSB of each byte transmitted first
01000000 10000000 00000000 The first byte is the Variable Length : Value is 0x02, LSB
transmitted first. The data bytes are 0x01, 0x00, LSB
transmitted first
01110100 11110110 The CRC is computed on the 3 bytes above. The CRC value is 0x6F2E
The LSByte of the CRC is sent first, LSB of byte first
Can the device be set to receive this bitstream correctly. I am specifically worried as to how the data bits (specifically the message length value) are interpreted by the Receiver - as if this is not interpreted correctly (ie in the opposite order of bits), the receiver will be expecting a msg of length 0x40 instead of 0x02.
If need be, I could manage to do the CRC in software, but the above point is critical.
