Hello welcome back.
So in this lesson we'll shall talk about the generic architecture behind interfacing
peripherals to
the ARM processor. As you may know, embedded systems that interact with the outside
world need some form of
peripheral device.
In a sense the set of peripherals attached to the embedded device determines the
uniqueness of
that device.
All ARM peripherals are memory mapped and this means the programming interface is a
set of memory addressed
registers and as we shall see when we begin coding the address of these registers
is an offset from a specific peripheral base address. Our simplified ARM embedded
device over here still
shows two items we've not talked about.
We've explained the ARM processor. We have explained the AHB and the APB buses
we've talked about memory
we've said the green rectangles are just examples of some peripherals that can be
connected to the ARM embedded
device.
We are left with the memory controller and the interrupt controller the memory controller
simply connects the
different types of memory we talked about to the processor. For example when the
power is turned on the
memory controller may be configured in hardware to allow certain memory devices to be
active. These
memory devices allow the initialization code to be executed.
Some memory devices must be set up in software though something like that DRAM.
We first have to set up the memory timings and the refresh rates using software before it
can be
accessed.
Now about the interrupt controller, it basically determines which peripheral can access
the processor at specific times.
There are two types of interrupt controllers available in ARM. The standard interrupt
control and the vectored
interrupt controller.
I shall leave the discussions on interrupt controllers for the future lessons when we are
talking about
interrupt only.
So this is all there is to it and I shall see you in the next lesson.