AN2797 Freescale Semiconductor / Motorola, AN2797 Datasheet - Page 25

• Manufacturer Part Number: AN2797
• Description: Migrating from IBM 750GX to MPC7447A
• Manufacturer: Freescale Semiconductor / Motorola

1.
As mentioned previously the MPC7447A also has a MMCR2 register with a one bit field,
MMCR2[THRESHMULT]. This can be used to extend the range of the MMCR0[THRESHOLD] field by
multiplying by 2 if set at 0 or by 32 if set at 1.
The MPC7447A also has a breakpoint address mask register (BAMR) that is used as a mask for debug purposes to
compare to IABR[0:29] when PMC1 is set to monitor event 42. This event monitors for IABR hits specifically by
checking they match BAMR. For example:
Match = ((IABR[0–29] & BAMR[0–29]) ==
(completion_address[0–29] & BAMR[0–29]))
5
5.1
Since there is no footprint/pin-out compatibility the easiest way to compare the IBM 750GX and MPC7447A pins
is to look at the different pins on the IBM 750GX that do not exist on the MPC7447A and then to look at the pins
present on the MPC7447A but not on the IBM 750GX.
5.1.1 IBM 750GX Uncommon Pins
Table 13
Freescale Semiconductor
PMC5 and PMC6 not present in IBM 750GX.
Hardware Considerations
Function
PMC3 event selector, 32 events
PMC4 event selector, 32 events
PMC5 event selector, 32 events
PMC6 event selector, 64 events
Signal Name
A1Vdd
A2Vdd
ABB
AGND
DBB
DBDIS
DBWO
DRTRY
Pin-out Comparison
shows the signal name, pin number and a description of the signal.
Pin Number
Y15
Y16
Y14
A10
W3
Y6
U7
A6
Migrating from IBM 750GX to MPC7447A, Rev. 1.0
Table 12. IBM 750GX MMCR1 to MPC7447A
Table 13. IBM 750GX additional signals
Active
IBM 750GX
MMCR0[PMC3SELECT]
MMCR0[PMC4SELECT]
N/A
N/A
Low
Low
Low
Low
Low
1
1
I/O
I/O
I/O
I
I
I
Description
PLL0 supply voltage
PLL1 supply voltage
Address bus busy
Ground for PLL
Data bus busy
Data bus disable
Data bus write only
Data retry
MPC7447A
MMCR0[PMC3SEL]
MMCR0[PMC4SEL]
MMCR0[PMC5SEL]
MMCR0[PMC6SEL]
Hardware Considerations
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