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Motorola VL-RISC MCF5202 User Manual

Page 13

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MOTOROLA

GATEWAY BOARD

13

"Function Codes for EC000 - (See NOTE 1)

" FC2 = ( (ATM & Normal-Access) # (IACK-Access) )

FC2 = ( ATM # (TT1&TT0) );

" FC1 = ( (ATMA & Normal-Access) # (IACK-Access) )

FC1 = ( ATMA # (TT1&TT0) );

" FC0 = ( (!ATMA & Normal-Access) # (IACK-Access) )

FC0 = ( !ATMA # (TT1&TT0) );

"-----------------------------------------------------------------------------------------

STATE_DIAGRAM psreg;

STATE PS0:

"RESET and waiting for TS to de-assert

IF TS THEN PS0;

"Wait for TS to de-assert

ELSE PS1;

STATE PS1:

"Waiting for TS to assert, Beginning of ColdFire cycle

IF !TS THEN PS1;

"Waiting for TS to assert

ELSE PS2;

STATE PS2:

"Beginning of 68K cycle, assert FCÕs and Address

IF HALT THEN PS2;

ÒIf HALT is asserted then stay in state 2

ELSE PS3;

"else goto state 3

STATE PS3:

"Assert other control signals

GOTO PS4;

"Unconditionally goto state 4

STATE PS4:

"Waiting for DTACK from 68K

IF (TT1 & TT0 & AVEC) THEN

"if TT[1:0]=11 (IACK and AVEC) then

PS5;

"goto state 5 (just DA the cycle)

ELSE

IF (DTACK) THEN

"else if (Normal or IACK without AVEC), look for DTACK

PS5;

"goto state 5

ELSE

PS4;

"else stay in state 4

STATE PS5:

"Data acknowledge to ColdFire

GOTO PS1;

"Unconditionally goto state 1

"------------------------------------------------------------------------------------------

STATE_DIAGRAM bsreg;

STATE BS0:

"Give the bus to CF, and wait for Request

BGCF=1;

"Assert Grant to CF

BG68K=0;

"Do not assert Grant to 68K

IF BR68K THEN

"If there is a Bus Request,

BS1;

"goto state 1

ELSE

"else if no request,

BS0;

"stay in state 0

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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