The background of ARM:
ARM is the acronym for Advanced RISC Machine, an UK based
company, which has pioneered the growth of RISC processor
Architecture.
What is RISC? RISC stands for Reduced Instruction Set Computer.
RISC based architecture although invented quite earlier
but has become popular and overtook its rival architecture
Complex Instruction Set Computer (CISC) somewhere during
late nineties. Most popular CISC architecture is 80x86 processors
from Intel. Recently Intel too has adopted RISC kind of
features and architecture in latest CPUs.
The advantage of RISC is in the simplicity (in terms of
processor resource consumption) of the instructions and
processing time. Each instruction takes only single clock
cycle. Overall power consumption is very less. Due to this
fast response, low power consumption and coding flexibility,
RISC architecture is highly suitable for embedded systems.
However there is one drawback with RISC, that is the instruction
set code is longer and takes more memory. This issue is
no more a concern with the growth in the memory technology.
As said earlier in the previous modules, we are using OKI
Semi's ML67Q4051 microcontroller in this course material.
The processor core used in ML67Q4051 is ARM7TDMI. ARM7TDMI
is the most used RISC core from ARM. ARM7TDMI core is old
and not suggested for new designs however it is good to
start learning from basic 32 bit processor core like ARM7DMI.
The architecture of ARM7TDMI is shown in figure below
Highlights of ARM7TDMI:
--There are 37 registers of 32 bit wide
in this processor core. 16 registers are available for the
programmer.
--It's pipeline architecture; that
is 3 instructions are processed simultaneously at 3 different
stages.
--The bus architecture is of Von
Neumann type where single 32-bit data bus carry both instructions
and data.
--The data-types can be of 8 bit
/16 bit/32 bit wide.
--Processor can run on seven different
modes based on the application requirement.
--Has built in 32x8 multiplier and
a 32 bit barrel shifter (both needed much for DSP functionality)
--This processor can also execute
another instruction set called THUMB state (16 bit) to give
the programmer
an option to use this processor like CISC processor. The
total instruction set can be tidier and takes less memory
space.
To study in-depth, the architecture and other capabilities
of ARM7DMI, please read the pdf file from the link below.
The content of this pdf file is simple and self-understanding.
http://www.arm.com/pdfs/DDI0210B_7TDMI_R4.pdf
OKI'S Microcntroller ML67Q4051:
Now let us read about the OKI Semiconductor's MCU ML67Q4051.
It has quite a good list of latest features.
The features of this MCU are,
--Has built in SRAM of 16 KB and FlashROM
of 128 KB.
--Has robust clock network
--Interrupt controller supports 41 interrupt
resources
--External memory controller to access
ROM, SRAM, and I/O connected to the external memory space.
--Has system timer of 16bit auto reload timer
with its interrupt given high priority.
--Built-in DMA controller enables direct data
transfer between memory-memory, I/O -memory, and between
I/O -I/O devices to spare the CPU from simple data transfer
burden.
--Watchdog timer to monitor the program
from running out of control and generate interrupt or reset
signal.
--The built-in 4-channel, 10-bit resolution
analog-to-digital converter supports two modes of operation:
Scan mode sequentially converts input from the selected
range of channels; select mode converts input from
a single channel.
--Has 15 general purpose I/O ports: 8channels
of 8-bit, 3 channels of 7-bit, 3 channels of 6-bits, and
one channel of 5 bits.
--Integrates one channel of I2C bus interface,
one I2S (serial audio interface) bus interface, one UART
interface, one SIO interface and one SPI interface.
--Real time clock (RTC) with 10,000-year calendar
with resolution down to 1 second.
--Flexible timer block with 6 channels of 16
bit timer.
--Has JTAG interface to debug the program from
a host computer
The internal architecture of this MCU is shown below.
To learn in-depth about this MCU please visit following
link:
http://www.okisemi.com/eu/docbox/ML67Q4050_4060-DS_rev1.2.pdf
Next Module - 6(Sample
programs in C)
Previous
Module - 4(Sample programs in C)
ABOUT THIS COURSE:
Totally EEHerald plan to bring 12 modules. You can
be assured of completing basic course in Embedded Systems
after studying and practicing exercises in all the modules.
We will give priority to programming and serial communications
(SPI, USB, CAN etc..) part. To receive a copy of total course
syllabus, please email to us.
This free tutorials on embedded systems is prepared
by embedded professionals with more than10 years of industrial
experience, however we want your feedback on this course
content; please email your questions, suggestions and comments
to editor@eeherald.com. Your questions on present modules
will be answered in the revised modules. We may change the
course content based on the majority of your requests and
feedbacks.
Please let your friends know about this course, we request
you to email this link to your friends and colleagues who
are interested in embedded system.
