Altera RapidIO MegaCore Function - Manual (Page 96)

4–50 Chapter 4: Functional Description
Logical Layer Modules
RapidIO MegaCore Function August 2014 Altera Corporation
User Guide
Table 4–13 lists the allowed read-request size encodings for RapidIO IP core variations
with a 64-bit Avalon-MM interface.
2
1111 (4) 0
0 1011
4 1 1011
6 or 8 0 1100
10, 12, 14, 16 1 1100
18, 20, 22, 24 1 1101
26, 28, 30, 32 1 1101
34, 36, 38, 40,
42, 44, 46, 48,
50, 52, 54, 56,
58, 60, 62, 64
1 1111
Notes to Table 4–12 :
(1) For write transfers in variations with 32-bit wide datapaths, odd burst sizes other than 1 are not supported. If one
occurs, the INVALID_WRITE_BURSTCOUNT bit in the Input/Output Slave Interrupt register is set, causing
sys_mnt_s_irq
to be asserted if enabled.
(2) Burst transfers of more than one Avalon-MM word must start on a double-word aligned Avalon-MM address. If
io_s_wr_burstcount is larger than one and io_s_wr_address[0] is not zero, the transfer completes in the
same manner as a failed mapping: the WRITE_OUT_OF_BOUNDS bit in the Input/Output Slave Interrupt
register is set and sys_mnt_s_irq is asserted if enabled.
(3) This is not a legal Avalon-MM byteenable pattern, but the RapidIO IP core supports it if user logic generates it.
(4) For all Avalon-MM write transfers with burstcount larger than 1, io_s_wr_byteenable must be set to 4’b1111.
If it is not, the transfer fails: the INVALID_WRITE_BYTEENABLE bit in the Input/Output Slave Interrupt
register is set and io_s_mnt_irq is asserted if enabled.
Table 4–13. Read Request Size Encoding (64-bit datapath)
Avalon-MM Values
RapidIO
Values
burstcount (1)
wdptr
(1'bx)
rdsize (1)
(4'bxxxx)
1 1'b0 4'b1011
2 1'b1 4'b1011
3–4 1'b0 4'b1100
5–8 1'b1 4'b1100
9–12 1'b0
4'b1101
13–16 1'b1
17–20 1'b0
4'b1110
21–24 1'b1
25–28 1'b0
4'b1111
29–32 1'b1
Note to Table 4–13 :
(1) For read transfers, the read size of the request packet is rounded up to the next supported size, but only the number
of words corresponding to the requested read burst size are returned.
Table 4–12. Write Request Size Encoding (32-bit datapath) (Part 2 of 2)
Avalon-MM Values RapidIO Values
burstcount (1) byteenable
(4'bxxxx)
address [0] (2)
(1'bx)
wdptr
(1'bx)
wrsize
(4'bxxxx)