mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 1135

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

27.4.2.2.1
The Flash module contains a 16-bit multiple-input signature register (MISR) for each Flash block to
generate a 16-bit signature based on selected Flash array data. If multiple Flash blocks are selected for
simultaneous compression, then the signature from each Flash block is further compressed to generate a
single 16-bit signature. The final 16-bit signature, found in the FDATA registers after the data compress
operation has completed, is based on the following logic equation which is executed on every data
compression cycle during the operation:
where MISR is the content of the internal signature register associated with each Flash block and DATA
is the data to be compressed as shown in
During the data compress operation, the following steps are executed:
Freescale Semiconductor
1. MISR for each Flash block is reset to 0xFFFF.
2. Initialized DATA equal to 0xFFFF is compressed into the MISR for each selected Flash block
3. DATA equal to the selected Flash array data range is read and compressed into the MISR for each
4. DATA equal to the selected Flash array data range is read and compressed into the MISR for each
5. If Flash block 0 is selected for compression, DATA equal to the contents of the MISR for Flash
6. If Flash block 1 is selected for compression, DATA equal to the contents of the MISR for Flash
7. If Flash block 2 is selected for compression, DATA equal to the contents of the MISR for Flash
8. If Flash block 3 is selected for compression, DATA equal to the contents of the MISR for Flash
9. The contents of the MISR for Flash block 0 are written to the FDATA registers.
DATA[0]
which results in the MISR containing 0x0001.
selected Flash block with addresses incrementing.
selected Flash block with addresses decrementing.
block 0 is compressed into the MISR for Flash block 0. If data in Flash block 0 was not selected
for compression, the MISR for Flash block 0 contains 0xFFFF.
block 1 is compressed into the MISR for Flash block 0.
block 2 is compressed into the MISR for Flash block 0.
block 3 is compressed into the MISR for Flash block 0.
+
MISR[15:0] = Q[15:0]
+
= Exclusive-OR
>
D Q
M0
Data Compress Operation
DATA[1]
MISR[15:0] = {MISR[14:0], ^MISR[15,4,2,1]} ^ DATA[15:0]
+
>
D Q
M1
+
DATA[2]
+
Figure 27-27. 16-Bit MISR Diagram
MC9S12XDP512 Data Sheet, Rev. 2.17
>
D Q
M2
+
Figure
DATA[3]
+
>
D Q
27-27.
M3
DATA[4]
+
>
D Q
M4
Chapter 27 512 Kbyte Flash Module (S12XFTX512K4V2)
+
DATA[5]
+
>
D Q
M5
...
DATA[15]
+
>
M15
D Q
Eqn. 27-1
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