Datasheet

 2009-2013 Microchip Technology Inc. DS60001156H-page 319
PIC32MX5XX/6XX/7XX
REGISTER 24-28: EMAC1MAXF: ETHERNET CONTROLLER MAC MAXIMUM FRAME LENGTH
REGISTER
Bit
Range
Bit
31/23/15/7
Bit
30/22/14/6
Bit
29/21/13/5
Bit
28/20/12/4
Bit
27/19/11/3
Bit
26/18/10/2
Bit
25/17/9/1
Bit
24/16/8/0
31:24
U-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0
— — — — — — — —
23:16
U-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0
— — — — — — — —
15:8
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-1
MACMAXF<15:8>
(1)
7:0
R/W-1 R/W-1 R/W-1 R/W-0 R/W-1 R/W-1 R/W-1 R/W-0
MACMAXF<7:0>
(1)
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 31-16 Unimplemented: Read as ‘0’
bit 15-0 MACMAXF<15:0>: Maximum Frame Length bits
(1)
These bits reset to 0x05EE, which represents a maximum receive frame of 1518 octets. An untagged
maximum size Ethernet frame is 1518 octets. A tagged frame adds four octets for a total of 1522 octets. If
a shorter/longer maximum length restriction is desired, program this 16-bit field.
Note 1: If a proprietary header is allowed, this bit should be adjusted accordingly. For example, if 4-byte headers
are prepended to frames, MACMAXF could be set to 1527 octets. This would allow the maximum VLAN
tagged frame plus the 4-byte header.
Note: Both 16-bit and 32-bit accesses are allowed to these registers (including the SET, CLR and INV registers).
8-bit accesses are not allowed and are ignored by the hardware.