Xilinx EDK 8.2i manual CacheLink Transactions

Xilinx CacheLink (XCL) Interface Description

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Table 2-8:MicroBlaze Cache Link signals

Signal Name	Description	VHDL Type	Direction
DCACHE_FSL_IN_Read	Read signal to D-side	std_logic	output
	return read data FSL
DCACHE_FSL_IN_Data	Read data from D-side	std_logic_vector	input
	return read data FSL	(0 to 31)
DCACHE_FSL_IN_Control	FSL control bit from D-	std_logic	input
	side return read data FSL
DCACHE_FSL_IN_Exists	More read data exists in	std_logic	input
	D-side return FSL
DCACHE_FSL_OUT_Clk	Clock output to D-side	std_logic;	output
	read access FSL
DCACHE_FSL_OUT_Write	Write new cache miss	std_logic;	output
	access request to D-side
	read access FSL
DCACHE_FSL_OUT_Data	Cache miss access (read	std_logic_vector	output
	address or write address	(0 to 31)
	+ write data + byte write
	enable) to D-side read
	access FSL
DCACHE_FSL_OUT_Control	FSL control-bit to D-side	std_logic;	output
	read access FSL. Used
	with address bits [30 to
	31] for read/write and
	byte enable encoding.
DCACHE_FSL_OUT_Full	FSL access buffer for D-	std_logic;	input
	side read accesses is full

CacheLink Transactions

All individual CacheLink accesses follow the FSL FIFO based transaction protocol:

•Access information is encoded over the FSL data and control signals (e.g. DCACHE_FSL_OUT_Data, DCACHE_FSL_OUT_Control, ICACHE_FSL_IN_Data, and ICACHE_FSL_IN_Control)

•Information is sent (stored) by raising the write enable signal (e.g. DCACHE_FSL_OUT_Write).

•The sender is only allowed to write if the full signal from the receiver is inactive (e.g. DCACHE_FSL_OUT_Full = 0). The full signal is not used by the instruction cache controller.

•Information is received (loaded) by raising the read signal (e.g. ICACHE_FSL_IN_Read)

•The receiver is only allowed to read as long as the sender signals that new data exists (e.g. ICACHE_FSL_IN_Exists = 1).

For details on the generic FSL protocol please refer to the “Fast Simplex Link (FSL) bus” data sheet (DS449).

MicroBlaze Processor Reference Guide	www.xilinx.com	57
UG081 (v6.0) June 1, 2006	1-800-255-7778