Flash Memory Array and Control
PXN20 Microcontroller Reference Manual, Rev. 1
12-2 Freescale Semiconductor
Figure 12-1. Flash Segmentation
12.1.1 Block Diagram
Figure 12-2 shows a block diagram of the flash memory module. The FBIU is addressed through the 
system bus while the flash control and status registers are addressed through the slave (peripheral) bus.
Figure 12-2. Flash System Block Diagram
Low-address space
High-address space
Mid-address space
Flash array blocks
Low-address space—256 KB 
Mid-address space—256 KB 
High-address space—1.5 MB
8 x 16 KB + 2 x 64 KB
2 x 128 KB
2x256KB
2x256KB
2x256KB
Flash bus
interface
unit
(FBIU)
Flash memory
Flash memory module
Flash core
Control/status
registers
interface
(MI)
V
FLASH
V
SS
V
DD
Slave
bus
System
bus