The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Inputs and Outputs
6
Inputs and Outputs
So far, our BASIC-52 circuit consists of the 8052-BASIC microcontroller, RAM, nonvolatile
memory for permanent program storage, and a serial interface to a host computer. Now
it’s time to add inputs and output interfaces that enable the system to monitor and control
devices outside of these circuits. The options include low-cost buffers and latches, as well
as programmable chips with features like individual bit control, automatic generation of
control signals, and the ability to configure a port as input, output, or bidirectional.
The Memory Map
But before we start adding components, it’s time to draw a memory map for the system.
The memory map is a diagram that shows the range of addresses a microcontroller or other
computer can access, along with each component that the computer reads or writes to and
the addresses where each component resides. The components may be memory chips like
RAM or EPROM, or they may be other components that the computer accesses by specifying
an address. Drawing a memory map helps to ensure that each component has a unique
address or range of addresses.
Figure 6-1 shows the memory map for our design. Each 64K area of external memory
consists of eight 8K blocks. Remember that 8 kilobytes equals 8192 in decimal, but 2000
in hexadecimal.
The Microcontroller Idea Book 87