Altera POS-PHY Level 2 and 3 Compiler - Manual (Page 56)

3–28 Chapter 3: Functional Description
Interface Signals
POS-PHY Level 2 and 3 Compiler User Guide © November 2009 Altera Corporation
Preliminary
Table 3–14 shows the Atlantic control interface signal definitions.
err Error indicator. err indicates that the current packet is aborted and should be discarded. err may be
asserted at any time during the current packet, but once asserted it can only be deasserted on the clock
cycle after eop is asserted. The POS-PHY MegaCore function sees this signal as either terr or rerr,
depending on the data flow direction. Conditions that can cause rerr to be set can be, but are not
limited to, FIFO buffer overflow, abort-sequence detection, missing SOP, missing EOP, and parity errors.
mty[2:0]
mty[1:0]
mty[0:0]
Word empty bytes. mty indicates the number of invalid (empty) bytes of data in dat. The mty bus
should always be all zero, except during the last transfer of a packet on dat. When eop is asserted, the
number of invalid packet data bytes on dat is specified by mty. The definition of mty is compatible
with the mod signal in the POS-PHY level 2 and 3 specifications.
mty = ‘000’, All dat bytes are valid
mty = ‘001’, dat[7:0] are invalid
mty = ‘010’, dat[15:0] are invalid
mty = ‘011’, dat[23:0] are invalid
mty = ‘100’, dat[31:0] are invalid
mty = ‘101’, dat[39:0] are invalid
mty = ‘110’, dat[47:0] are invalid
mty = ‘111’, dat[55:0] are invalid
An 8-bit dat bus requires no mty signal
A 16-bit dat bus requires a mty[0] signal
A 32-bit dat bus requires a mty[1:0] signal
A 64-bit dat bus requires a mty[2:0] signal
mty can only be non-zero when eop is asserted.
Table 3–13. Atlantic Interface Data Signals (Part 2 of 2)
Signal Description