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ADS125H02数据通讯格式及CRC校验问题

Other Parts Discussed in Thread: ADS125H02

一、根据手册关于CRC部分的介绍:

The following is a general procedure to compute the CRC value:
1. Left shift the concatenated 1-, 2-, 3-, or 4-byte argument (if required) to create a new 40-bit data value
(the starting data value). The shifted data are padded with ones to the right of the argument.
2. Align the MSB of the CRC polynomial (100000111) to the left-most, logic-one value of the data.
3. Perform an XOR operation on the data value with the aligned CRC polynomial. The XOR operation
creates a new, shorter length value. The bits of the data values that are not in alignment with the CRC
polynomial drop down and append to the right of the new XOR result.
4. When the XOR result is less than 100000000b, the procedure ends, yielding the 8-bit CRC value.
Otherwise, continue with the XOR operation shown in step 2 using the current data value. The number of
loop iterations depends on the value of the initial data.

第1条中,将所有数据“左移扩展为40bit,最右边用1补齐”,与传统的crc计算方法不一致,传统的计算方法是在数据末尾补8个0。是手册笔误还是本就与正常的crc计算方法不同。

二、数据手册中就spi数据的通讯格式没有给出详细的描述。该AD的通讯方式是lsb优先还是msb优先?例如要传输0xABCD,是按照“1010 1011 1100 1101”传输还是按照“1011 0011 1101 0101”传输呢?

请相关专家解释一下,感谢。