MCF548x Reference Manual, Rev. 3
30-42 Freescale Semiconductor

30.3.3.35 FEC CRC and Transmit Frame Control Word Register (FECCTCWR)

The FEC can be sent a control word (32-bit) with additional instructions on how to transmit the current

frame. This control word instructs the FEC to append or not append a CRC value to the frame being

transmitted. Control of the transmit frame control word and its contents are provided in this register.

Table 30-41. FECFRST Field Descriptions

Bits Name Descriptions
31–26 Reserved, should be cleared
25 SW_RST Software Reset. This bit controls the soft reset of the FEC FIFOs. A soft reset will reset the
FIFO pointers and byte counters but notthe status and control registers. To cause a soft
reset this bit should be set and then cleared by application software.
24 RST_CTL Reset control. Setting this bit allows the FEC controller to perform a soft reset of the FIFOs
when the FEC is disabled (ECR[ETHER_EN] cleared).
23–0 Reserved, should be cleared
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
R000000CRCTFCW00000000
W
Reset0000000000000000
1514131211109876543210
R0000000000000000
W
Reset0000000000000000
Reg
Addr
MBAR + 0x91C8 (FEC0), 0x99C8 (FEC1)

Figure 30-38. FEC CRC and Transmit Frame Control Word Register (FECCTCWR)

Table 30-42. FECCTCWR Field Descriptions

Bits Name Descriptions
31–26 Reserved, should be cleared
25 CRC CRC enable. This bit is associated with the TC field in FEC’s Transmit Frame Control Word.
A 1 in this bit location translates to TC = 1 and instructs FEC to append CRC to the current
transmit frame.
24 TFCW Transmit frame control word enable. This bit controls whether a “control word” is appended
to the frame being transferred to the transmit FIFO.
23–0 Reserved, should be cleared