Information

49.4.7.1 FIFO data ready flag
The FIFO data ready flag is set based on the number of entries in the FIFO and the FIFO
watermark configuration.
The transmit data ready flag is set when the number of entries in any of the enabled
transmit FIFOs is less than or equal to the transmit FIFO watermark configuration and is
cleared when the number of entries in each enabled transmit FIFO is greater than the
transmit FIFO watermark configuration.
The receive data ready flag is set when the number of entries in any of the enabled
receive FIFOs is greater than the receive FIFO watermark configuration and is cleared
when the number of entries in each enabled receive FIFO is less than or equal to the
receive FIFO watermark configuration.
The FIFO data ready flag can generate an interrupt or a DMA request.
49.4.7.2 FIFO warning flag
The FIFO warning flag is set based on the number of entries in the FIFO.
The transmit warning flag is set when the number of entries in any of the enabled
transmit FIFOs is empty and is cleared when the number of entries in each enabled
transmit FIFO is not empty.
The receive warning flag is set when the number of entries in any of the enabled receive
FIFOs is full and is cleared when the number of entries in each enabled receive FIFO is
not full.
The FIFO warning flag can generate an Interrupt or a DMA request.
49.4.7.3 FIFO error flag
The transmit FIFO error flag is set when the any of the enabled transmit FIFOs
underflow. After it is set, all enabled transmit channels repeat the last valid word read
from the transmit FIFO until TCSR[FEF] is cleared and the next transmit frame starts.
All enabled transmit FIFOs must be reset and initialized with new data before
TCSR[FEF] is cleared.
RCSR[FEF] is set when the any of the enabled receive FIFOs overflow. After it is set, all
enabled receive channels discard received data until RCSR[FEF] is cleared and the next
next receive frame starts. All enabled receive FIFOs should be emptied before
RCSR[FEF] is cleared.
Data FIFO
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
1400
Preliminary
Freescale Semiconductor, Inc.
General Business Information