Cypress EX-USB FX3, Programmer'S Manual

Page: 26 / 192

26 FX3 Programmers Manual, Doc. # 001-64707 Rev. *C
FX3 Overview
Figure 3-3. Internal Memory Unit
The 512 KB system memory can be broadly divided into three. The first few entries of this area is
used to store DMA instructions (also known as descriptors). The DMA hardware logic executes
instructions from these locations. The last 16 K of the system memory shadows the translation table
necessary for cache operations. The remaining area can be used as user code area and/or user
data area and/or DMA buffer area.
Note
1 entry = 4 words
3.4 Interrupts
Interrupt exceptions are facilitated using the FIQ and IRQ lines of the ARM9 processor. The ISR
branch instruction for each of these interrupts is provided in the 32 byte exception table located at
the beginning of the ITCM.
The embedded PL192 vectored interrupt controller (VIC) licensed from ARM provides a hardware
based interrupt management system that handles interrupt vectoring, priority, masking and timing,
providing a real time interrupt status. The PL192 VIC supports 32 'active high' interrupt sources, the
ISR location of which can be programmed into the VIC. Each interrupt can be assigned one of the 15
programmable priority levels; equal priority interrupts are further prioritized based on the interrupt
number. While each interrupt pin has a corresponding mask and enable bits, interrupts with a
particular priority level can all be masked out at the same time if desired. Each of the '32-interrupt'
can be vectored to one of the active low FIQ or IRQ outputs of the VIC that are directly hooked to the
corresponding lines of the ARM 9 CPU. PL192 also supports daisy chained interrupts, a feature that
is not enabled in FX3.
Note
Other exceptions include reset, software exception, data abort, and pre-fetch abort.
System Bus
AHB
Slave
Interface
Memory controller for System
memory (AHB to SRAM
protocol con
cpower management)
(Bus Slave)
S
512 KB SRAM