SBAA106A June   2020  – August 2021 ADS112C04 , ADS112U04 , ADS114S06 , ADS114S08 , ADS122C04 , ADS122U04 , ADS1235 , ADS1235-Q1 , ADS124S06 , ADS124S08 , ADS1259 , ADS1259-Q1 , ADS125H01 , ADS125H02 , ADS1260 , ADS1260-Q1 , ADS1261 , ADS1262 , ADS1263 , ADS127L01 , ADS131A02 , ADS131A04 , ADS131M04 , ADS131M06 , ADS131M08

 

  1.   Trademarks
  2. 1Introduction
  3. 2Simple Checksum
    1. 2.1 Checksum Code Example
  4. 3CRC
    1. 3.1 CRC Generic Computations
      1. 3.1.1 Using XOR Bitwise Computation
      2. 3.1.2 Using Lookup Tables
        1. 3.1.2.1 Table Initialization
        2. 3.1.2.2 CRC Computation
      3. 3.1.3 CRC Computation Differences Between the ADS122U04 and ADS122C04
        1. 3.1.3.1 Byte Reflection Example
        2. 3.1.3.2 Reassembling Data Using Byte Reflection for CRC Computation
  5. 4Hamming Code
    1. 4.1 Hamming Code Computation
      1. 4.1.1 Hamming Code Computation Example
        1. 4.1.1.1 Counting Bits for Parity and Checksum Computations
          1. 4.1.1.1.1 Example of Counting Set Bits in the Data
          2. 4.1.1.1.2 Example of Counting Set Bits Using a Lookup Table
      2. 4.1.2 Validation of Transmitted Data
        1. 4.1.2.1 Hamming Validation
        2. 4.1.2.2 Checksum Validation
        3. 4.1.2.3 Error Correction
  6. 5Summary
  7. 6References
  8. 7Revision History

4.1.1.1 Counting Bits for Parity and Checksum Computations

There are a couple of possible methods for determining the number of "1" bits within a value being considered. One method is to simply check the data bit by bit. A faster method is using a lookup table.