ZHCSRW7 march 2023 AFE781H1 , AFE881H1
PRODUCTION DATA
The AFEx81H1 register map runs on the internal clock domain. Both the SPI and UBM packets are synchronized to this domain. This synchronization adds a latency of 0.4 µs to 1.22 µs (1.5 internal clocks), with respect to the rising edge of CS or the STOP bit of the last byte of the UBM packet.
The effect of clock synchronization on UBM communication is not evident because of the lower speed and asynchronous nature of UBM communication.
In SPI mode, if changing register bits CONFIG.DSDO, CONFIG.FSDO, or CONFIG.CRC_EN, keep CS high for at least two clock cycles before issuing the next frame. Frame data corruption can occur if the two extra cycles are not used. The following are examples of frame corruption:
Send a NOP command (SDI = 0x00_0000) after setting the DSDO, FSDO, and CRC_EN bits to prevent the corrupted frames from impacting communication. Sending a NOP after CONFIG.CRC_EN is set still generates a CRC error, and is reported in the STATUS portion of SDO. To avoid false errors, wait approximately 2 µs after setting CONFIG.CRC_EN before sending the next frame.