Freescale semiconductor, inc – Motorola VL-RISC MCF5202 User Manual
Page 14
14
GATEWAY BOARD
MOTOROLA
STATE BS1:
"Got a Request, wait for CF to quit driving the bus
BGCF=0; BG68K=0;
"Do not assert either Grant
IF !BDCF THEN
"If CF is not driving the bus,
BS2;
"then goto state 2
ELSE
"else if CF is driving the bus,
BS1;
"stay in state 1
STATE BS2:
"Done driving the bus, give the bus to 68K, wait for
Request to go away
BGCF=0;
"Do not assert Grant to CF
BG68K=1;
"Assert Grant to 68K
IF BR68K THEN
"If 68K is still requesting the bus,
BS2;
"then stay in state 2
ELSE
"else if no longer requesting the bus,
BS3;
"goto state 3
STATE BS3:
"Request went away, delay one clock, then bus back to CF
BGCF=0; BG68K=0;
"Do not assert either Grant
GOTO BS0;
"goto state 0
"-------------------------------------------------------------------------------------------
"NOTE 1:
"
ATMa
ATMd
TT1
TT0
FC2
FC1
FC0
Notes
"
"
0
0
0
0
0
0
1
Normal User Data
"
1
0
0
0
0
1
0
Normal User Instruction
"
0
1
0
0
1
0
1
Normal Supervisor Data
"
1
1
0
0
1
1
0
Normal Supervisor Instruction
"
X
X
0
1
0
0
0
Reserved
"
X
X
1
0
?
?
?
Emulator Access
"
X
X
1
1
1
1
1
CPU Space or IACK
"NOTE 2:
"RnW MODE
A0
(!SIZ1&
AENORM
AEIACK
UDS
LDS
OExxxx
Notes
"
SIZ0)
" 1
1
0
1
1
0
1
0
OEBA16
Read,16-bit,even,byte,Normal
" 1
1
0
1
0
1
1
1
OEBA8
Read,16-bit,even,byte,IACK
" 1
1
0
0
x
x
1
1
OEBA16
Read,16-bit,even,!byte
" 1
1
1
1
x
x
0
1
OEBA16
Read,16-bit,odd, byte
" 1
1
1
0
x
x
1
1
OEBA16
Read,16-bit,odd,!byte (N/A)
" 1
0
x
x
x
x
0
1
OEBA8
Read,8-bit
" 0
1
0
1
x
x
1
0
OEAB16
Write,16-bit,even,byte
" 0
1
0
0
x
x
1
1
OEAB16
Write,16-bit,even,!byte
" 0
1
1
1
x
x
0
1
OEAB16
Write,16-bit,odd,byte
" 0
1
1
0
x
x
1
1
OEAB16
Write,16-bit,odd,!byte (N/A)
" 0
0
x
x
x
x
0
1
OEAB8
Write,8-bit
END
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