MCF548x Reference Manual, Rev. 3
29-40 Freescale Semiconductor

29.2.5.6 USB Endpoint n FIFO Status Register (EPnFSR)

Table 29-40. EPnFDR Field Descriptions

Bits Name Description
31–0 TXDATA This is the transmit FIFO write data
31–0 RXDATA This is the receive FIFO read data
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
R IP TXW 0 0 FRM FAE RXW UF OF FR FU ALRM EMT
W
Reset0 0Uninitialized0000000000 0 1
15141312111098765432 1 0
R0 0 0 00000000000 0 0
W
Reset Uninitialized
Reg
Addr
MBAR + 0xB454 (EP0FSR); 0xB484 (EP1FSR); 0xB4B4 (EP2FSR); 0xB4E4 (EP3FSR);
0xB514 (EP4FSR); 0xB544 (EP5FSR); 0xB574 (EP6FSR)

Figure 29-46. USB Endpoint n FIFO Status Register (EPnFSR)

Table 29-41. EPnFSR Field Descriptions

Bits Name Description
31 IP Illegal pointer. This bit signifies an illegal pointer condition in the FIFO controller. The assertion of
this bit will cause a FIFO error condition (ERR) in the EPnISR unless the EPnFCR[IPMSK] bit is
set. This bit will remain set until a one is written to this bit location.
0 No illegal pointer condition.
1 An address outside the FIFO controller’s memory range has been written to one of the
user-visible pointers.
30 TXW Transmit wait states. This bit indicates that the current IN (transmit) transaction from the USB is
incurring wait states because there is not enough data in the FIFO to satisfy the read request. Even
though the FIFO is not in a catastrophic state (i.e., normal operation can proceed without flushing
the FIFO), this may result in an inadvertent short packet being transmitted for the current IN
transaction.
The assertion of this bit will cause a FIFO error condition (ERR) in the EPnISR unless the TXWMSK
bit in the EPnFCR is set. This bit will remain set until a one is written to this bit location.
0 No transmit wait condition.
1 Transmit wait condition.
29–28 Reserved, should be cleared.
27–24 FRM Frame indicator. This bus provides a frame status indicator for non-DMA applications.
1000 A frame boundary has occurred on the [31:24] byte of the data bus
0100 A frame boundary has occurred on the [23:16] byte of the data bus
0010 A frame boundary has occurred on the [15:8] byte of the data bus
0001 A frame boundary has occurred on the [7:0] byte of the data bus