Reference Only Allayer Confidential MPC860 AL300A Interface

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Reference Only Allayer Confidential MPC860 AL300A Interface

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APPLICATION BRIEF MPC860 AL300A INTERFACE
Reference Only Allayer Confidential
MPC860 AL300A Interface
Overview
AL300A uses burst cycles transfer. data transfers which don't require four-full cycles burst, AL300A will terminate burst early. However, Motorola MPC860 doesn't respond early burst termination causes data corruption when AL300A terminates burst early starts single access immediately after receiving packet. patch logic will this masking extra cycles when AL300A terminates burst. Also, MPC860 integrated arbiter take away grant before AL300A releases during transfer, while AL300A needs hold minimum four eight burst accesses. This cause MPC860 hang because contention. glue logic described below will this implementing external arbiter when MPC860 arbiter disabled. combined logic fitted simple programmable logic device (PLD) such 22V10. Sample code provided this document. required until MPC860 fully supports burst terminating allows external master hold specified data sheet.
Implementation
AL300A will issue early burst termination de-asserting BDIP# signal during burst cycle. AL300A will start next cycle asserting after termination burst cycle. However, MPC860 will ignore BDIP# signal finish burst cycle issuing remaining acknowledge (TA#) signals. AL300A assumes that these extra signals acknowledgement from cycle which issued after burst termination. This causes data corruption since AL300A begins cycle while MPC860 finishing burst cycle. eliminate this data corruption, glue logic must mask extra AL300A when early burst termination issued from AL300A.
MPC860
BRn_MPC BGn_MPC TAn_MPC
BRn_AL300
AL300A
(22V10)
BGn_AL300 TAn_AL300
BDIP# RST#
BDIPn CSn_AL300 RSTn
BDIP# RST#
Figure Block Diagram MPC860 AL300A Glue Logic
12/99
Reference Only Allayer Confidential
MPC860 AL300A Interface
glue logic must intercept signal both directions since bi-directional signal. AL300A direction from MPC860, must masked when burst terminates early. From AL300A MPC860, signal transparent. Figure shows that glue logic intercepts (Bus Request) (Bus Grant) signals. This used contention problem when MPC860 takes away from AL300A during multiple burst cycles. internal arbiter used, MPC860 expects external master finish current cycle when taken away relinquishes bus. However, AL300A will continue finish burst cycle since expects that MPC860 will take away only when (Bus Busy) signal de-asserted. resolve this issue, external arbiter used that MPC860 can't take away before AL300A releases bus. Since only master devices exist bus, glue logic simple arbiter. allows master hold once granted gives higher priority. pull-up resister MPC860 will disable internal arbiter RESET. following code used implement arbiter well masking logic. uses 22V10 written ABEL HDL. speed faster) expected clock.
MODULE Burst_tb TITLE 'AL300-MPC860 Burst termination arbiter' This module things Mask extra AL300 terminated burst after three accesses. arbiter, fixed higher priority, preemption allowed. Implementation fitted Gal22V10 with Vantis DisignDirect software. Written Able format. State machine mask[4:1] Memory access from least three cycles. 0000 idle !BGn_AL300 !TSn 1000 1001 !TAn_MPC +<-0001 !BDIPn !TAn_MPC !TAn_MPC +<-0010 !BDIPn !TAn_MPC !TAn_MPC +<-0011 !BDIPn !TAn_MPC !TAn_MPC +<-0100
12/99
Reference Only Allayer Confidential
MPC860 AL300A Interface
declarations Pinout PAL22V10 24DIP RSTn BDIPn CSn_AL300 BRn_AL300 BRn_MPC BGn_AL300 BGn_MPC TAn_MPC TAn_AL300 mask1 mask2 mask3 mask4 mask5 TAn_MPC_OE States mask s0000 s1000 s1001 s0001 s0010 s0011 s0100 Equations Arbitration BGn_AL300.d !RSTn !(!BRn_AL300 BGn_MPC.q BRn_MPC !BGn_AL300.q !BRn_AL300); AL300 BGn_AL300.clk CLK; BGn_MPC.d !RSTn !(!BRn_MPC BGn_AL300.q !BGn_MPC.q !BRn_MPC); BGn_MPC.clk CLK; CLK; Burst Termination mask5.d !BGn_AL300 !mask4 mask1 mask2 mask3 );// AL300 burst duration TAn_AL300.oe mask5; TAn_AL300 TAn_MPC !(!mask4 (mask1 mask2 mask3)); TAn_MPC_OE.d !CSn_AL300; TAn_MPC_OE.clk CLK; TAn_MPC.oe TAn_MPC_OE; [mask4, mask3, mask2, mask1]; AL300 common clock common common BDIPn from AL300 AL300 common
istype 'reg_d'; AL300 istype 'reg_d'; istype 'com'; istype 'com'; node node node node node node istype istype istype istype istype istype 'reg_d'; 'reg_d'; 'reg_d'; 'reg_d'; 'reg_d'; 'reg_d'; AL300 internal states burst termination
AL300
12/99
Reference Only Allayer Confidential
MPC860 AL300A Interface
TAn_MPC TAn_AL300;
State_diagram mask state s0000: (RSTn !BGn_AL300 !TSn) then s1000; else s0000; state s1000: (!RSTn) then s0000; else s1001; state s1001: (!RSTn) then s0000; else s0001; state s0001: (!RSTn) then s0000; else (!BDIPn !TAn_MPC) then s0010; else (!TAn_MPC) then s0000; else s0001; state s0010: (!RSTn) then s0000; else (!BDIPn !TAn_MPC) then s0011; else (!TAn_MPC) then s0000; else s0010; state s0011: (!RSTn) then s0000; else (!BDIPn !TAn_MPC) then s0100; else (!TAn_MPC) then s0000; else s0011; state s0100: (!RSTn) then s0000; else (!TAn_MPC) then s0000; else s0100; Burst_tb
Once glue logic been implemented correctly, following waveforms used correct early burst termination arbitration. These waveforms illustrate that glue logic correctly terminated burst cycles with early termination happening third forth cycle four-cycle burst. last figure also shows full burst that's terminated early. There need terminating burst second cycle because AL300A will issue single access instead. Note: arbitration also involved following waveforms.
12/99
Reference Only Allayer Confidential
MPC860 AL300A Interface
Figure Waveform Early Burst Termination Cycle with Burst Cycles
Figure Waveform Early Burst Termination Cycle with Three Burst Cycles
12/99
Reference Only Allayer Confidential
MPC860 AL300A Interface
Figure Waveform Full Burst Cycle without Early Burst Termination
12/99
Reference Only Allayer Confidential

Reference Only Allayer Confidential MPC860 AL300A Interface

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