Datasheet

PIC32MX5XX/6XX/7XX
DS60001156H-page 304  2009-2013 Microchip Technology Inc.
REGISTER 24-15: ETHSTAT: ETHERNET CONTROLLER STATUS 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
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
BUFCNT<7:0>
15:8
U-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0
— — — — — — — —
7:0
R/W-0 R/W-0 R/W-0 U-0 U-0 U-0 U-0 U-0
ETHBUSY
(1)
TXBUSY
(2)
RXBUSY
(2)
— — — — —
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 31-24 Unimplemented: Read as ‘0’
bit 23-16 BUFCNT<7:0>: Packet Buffer Count bits
Number of packet buffers received in memory. Once a packet has been successfully received, this register
is incremented by hardware based on the number of descriptors used by the packet. Software decrements
the counter (by writing to the BUFCDEC bit (ETHCON1<0>) for each descriptor used) after a packet has
been read out of the buffer. The register does not roll over (0xFF to 0x00) when hardware tries to increment
the register and the register is already at 0xFF. Conversely, the register does not roll under (0x00 to 0xFF)
when software tries to decrement the register and the register is already at 0x0000. When software attempts
to decrement the counter at the same time that the hardware attempts to increment the counter, the counter
value will remain unchanged.
When this register value reaches 0xFF, the RX logic will halt (only if automatic Flow Control is enabled)
awaiting software to write the BUFCDEC bit in order to decrement the register below 0xFF.
If automatic Flow Control is disabled, the RXDMA will continue processing and the BUFCNT will saturate at
a value of 0xFF.
When this register is non-zero, the PKTPEND status bit will be set and an interrupt may be generated,
depending on the value of the ETHIEN bit <PKTPENDIE> register.
When the ETHRXST register is written, the BUFCNT counter is automatically cleared to 0x00.
Note: BUFCNT will not be cleared when ON is set to ‘0’. This enables software to continue to utilize
and decrement this count.
bit 15-8 Unimplemented: Read as ‘0’
bit 7 ETHBUSY: Ethernet Module busy bit
(1)
1 = Ethernet logic has been turned on (ON (ETHCON1<15>) = 1) or is completing a transaction
0 = Ethernet logic is idle
This bit indicates that the module has been turned on or is completing a transaction after being turned off.
bit 6 TXBUSY: Transmit Busy bit
(2)
1 = TX logic is receiving data
0 = TX logic is idle
This bit indicates that a packet is currently being transmitted. A change in this status bit is not necessarily
reflected by the TXDONE interrupt, as TX packets may be aborted or rejected by the MAC.
Note 1: This bit will be set when the ON bit (ETHCON1<15>) = 1.
2: This bit will be cleared when the ON bit (ETHCON1<15>) = 0.