JAJSPC7A December 2022 – August 2023 ADS131B23
PRODUCTION DATA
Register map CRCs in the ADS131B23 detect unintended changes in the register map contents. The register map is divided into four sections.
Section 0 includes read-only bits that update the values based on the device state or ADC2y conversion data. Therefore, section 0 does not offer any register map CRC check.
Sections 1 to 3 include the device configuration bits and provide independent CRC checks. Enable the register map CRC for each section using the REG_MAPx_CRC_EN (x = 1 to 3) bits. When the register map CRC for a section is enabled, the device constantly calculates a 16-bit CRC value across that register map section and compares the internal calculation result against the CRC value provided by the user in the REG_MAPx_CRC_VALUE[15:0] bit field. If the internal calculation result and the REG_MAPx_CRC_VALUE[15:0] do not match, the REG_MAPx_CRC_FAULTn is set to 0b. No other action is taken by the device in the event of a register map section CRC fault.
The CRC calculation begins with the MSB of the first register in the respective register section and ends with the LSB of the last specified register in the respective register section using the polynomial selected in the CRC_TYPE bit. Table 8-17 shows the exact registers that are covered by the register map CRC in each section. Two types of CRC polynomials are available: CCITT CRC and ANSI CRC (CRC-16). See the Communication Cyclic Redundancy Check (CRC) section for details on the CRC polynomials. The CRC calculations are initialized with the seed value of FFFFh.
REGISTER SECTION | REGISTERS COVERED BY REGISTER MAP CRC |
---|---|
0 | N/A |
1 | 40h to 59h |
2 | 80h to A3h |
3 | C0h to E3h |
The CRC calculation is implemented serially, one register map bit per OSCD period. Therefore, unintended bit changes are not indicated immediately in the REG_MAPx_CRC_FAULTn fault flags, but can take up to tp(REG_MAP_CRC).
Use the following procedure to change register bits in sections 1 to 3 without accidentally causing a REG_MAPx_CRC_FAULTn indication:
Register bits in section x can also be changed while the register map section x CRC is enabled, as discussed in the following procedure, but can cause unintended REG_MAPx_CRC_FAULTn indications.