SLASFM1A June 2025 – December 2025 AFE10004-EP
PRODUCTION DATA
If the device is used in a noisy environment, error checking is used to check the integrity of SPI data communication between the device and the host processor. This feature is enabled by setting the CRCEN bit.
The error checking scheme is based on the CRC-8-ATM (HEC) polynomial x8 + x2 + x + 1 (that is, 100000111). When error checking is enabled, the serial interface access cycle width is 32 bits. The normal 24-bit SPI data are appended with an 8-bit CRC polynomial by the host processor before sending the data to the device. Table 6-16 shows the SPI error checking serial interface access cycle. In all serial interface readback operations the CRC polynomial is output on the SDO pin as part of the 32-bit cycle.
| BIT | FIELD | DESCRIPTION |
|---|---|---|
| 31 | R/W | Identifies the communication as a read or write command to the
addressed register. R/W = 0 sets a write operation. R/W = 1 sets a read operation. |
| 30:24 | A[6:0] | Register address. Specifies the register to be accessed during the read or write operation. |
| 23:8 | DI[15:0] | Data cycle bits. If a write command, the data cycle bits are the values to be written to the register with address A[6:0]. If a read command, the data cycle bits are don’t care values. |
| 7:0 | CRC | 8-bit CRC polynomial. |
The device decodes the 32-bit access cycle to compute the CRC remainder on CS rising edges. If no error exists, the CRC remainder is zero and data are accepted by the device. A write operation failing the CRC check causes the data to be ignored by the device.
After the write command, issue a second access cycle to determine the device status, including the CRC error check result (SPICRC bit), on the SDO pin. Table 6-17 shows the SPI write operation error checking cycle. After being set, write a 1 to the SPICRC bit in the Status register to clear the bit.
| BIT | FIELD | DESCRIPTION |
|---|---|---|
| 31:24 | STATUS[7:0] | Lower eight bits of the status register. |
| 23:8 | DO[15:0] | Echo data from previous access cycle. |
| 7:0 | CRC | Calculated CRC value of bits 31:8. |
To get the requested data on the SDO pin, follow a read operation with a second access cycle. As in the case of a write operation, the device status is output on the SDO pin; see also Table 6-18.
| BIT | FIELD | DESCRIPTION |
|---|---|---|
| 31:24 | STATUS[7:0] | Lower eight bits of the Status register. |
| 23:8 | DO[15:0] | Readback data requested on previous access cycle. |
| 7:0 | CRC | Calculated CRC value of bits 31:8. |