28-07-2012, 02:59 PM
Hardware Architectures for ES
[attachment=29399]
Programming an ES
To program an ES one must have a fair understanding of the h/w needed to run such s/w
This chapter give a very brief background
We will begin with general hardware architecture of a generic embedded system
ES is built around a CPU
Function- same as that of a desktop CPU, but less powerful
Has limited internal memory + optional external memory, when needed
Other peripherals, as required by the application
The next slide show the major functional blocks
Processor
ES processor can be of three types:
Micro-controller
Microprocessor
Digital Signal Processor
Most important Specification of a processor?
The clock speed indicate?
The word-length indicate?
What does the clock speed indicate? How is it specified?
by clock frequency : xxx MHz / GHz; No. of clock cycles / sec. more cycles more instructions/sec faster the processor
What does the word-length indicate? How is it specified?
Data word-length [8-, 16-, 32-bit etc,]
Precession & Address Space.
Micro-controller
They come with 8-bit, 16-bit and 32-bit
The 8-bit micro-controllers are used for process control applications, such as the ones found in toys and smart cards.
16-bit or 32-bit processor- if higher processing power and memory are required.
Microprocessor
16-bit and 32-bit microprocessors are available from ARM, Atmel, Intel, Motorola, National Semiconductors, AMD, Intel etc.
ES development with these processors needs a great deal of peripheral circuitry.
Processors with higher clock speeds and word-length, used for high-end applications such as handheld computers, Internet Access Devices, etc.
Digital Signal Processor: DSP
Specially designed processor to handle signals
Processing audio and video signals- is very complex,
Convert the signals into frequency domain using Fourier Transforms, and analyze the spectrum of the signal in frequency domain, is another imp op.
Filtering - unwanted frequencies are removed, is an essential operation.
Memory : Flash memory
Flash memory :
Fast EEPROM. Also non-volatile,.
It can be erased one block at a time, and programmed one bit at a time.
Flash memory devices are high density, low cost, fast (to read but not to write), and can be updated by the embedded system.
Used extensively in ES that contain the embedded OS
Latches
What are Latches?
Processor-based systems need to drive external devices such as LED displays, relays, etc. The processor does not interact directly with these devices. Flip-flop logic chips are used to drive the external devices. These chips hold the processor output data to be sent to the external devices are called latches
Buffers
What are Buffers?
Devices for temporary storage.
Processor does not directly handle devices like keypads, switches, etc since they are very slow.
When processor needs to obtain data from such external devices we use Octal buffers to read data from the external devices onto the common data bus.
Crystal
The CPU needs a clock source, and a crystal oscillator generates the clock. You need to choose the crystal based on the clock frequency of the processor. Many micro-controllers provide an on-chip oscillator, and you connect an external crystal or ceramic resonator. The clock generation circuitry determines the various states of the machine cycle.
[attachment=29399]
Programming an ES
To program an ES one must have a fair understanding of the h/w needed to run such s/w
This chapter give a very brief background
We will begin with general hardware architecture of a generic embedded system
ES is built around a CPU
Function- same as that of a desktop CPU, but less powerful
Has limited internal memory + optional external memory, when needed
Other peripherals, as required by the application
The next slide show the major functional blocks
Processor
ES processor can be of three types:
Micro-controller
Microprocessor
Digital Signal Processor
Most important Specification of a processor?
The clock speed indicate?
The word-length indicate?
What does the clock speed indicate? How is it specified?
by clock frequency : xxx MHz / GHz; No. of clock cycles / sec. more cycles more instructions/sec faster the processor
What does the word-length indicate? How is it specified?
Data word-length [8-, 16-, 32-bit etc,]
Precession & Address Space.
Micro-controller
They come with 8-bit, 16-bit and 32-bit
The 8-bit micro-controllers are used for process control applications, such as the ones found in toys and smart cards.
16-bit or 32-bit processor- if higher processing power and memory are required.
Microprocessor
16-bit and 32-bit microprocessors are available from ARM, Atmel, Intel, Motorola, National Semiconductors, AMD, Intel etc.
ES development with these processors needs a great deal of peripheral circuitry.
Processors with higher clock speeds and word-length, used for high-end applications such as handheld computers, Internet Access Devices, etc.
Digital Signal Processor: DSP
Specially designed processor to handle signals
Processing audio and video signals- is very complex,
Convert the signals into frequency domain using Fourier Transforms, and analyze the spectrum of the signal in frequency domain, is another imp op.
Filtering - unwanted frequencies are removed, is an essential operation.
Memory : Flash memory
Flash memory :
Fast EEPROM. Also non-volatile,.
It can be erased one block at a time, and programmed one bit at a time.
Flash memory devices are high density, low cost, fast (to read but not to write), and can be updated by the embedded system.
Used extensively in ES that contain the embedded OS
Latches
What are Latches?
Processor-based systems need to drive external devices such as LED displays, relays, etc. The processor does not interact directly with these devices. Flip-flop logic chips are used to drive the external devices. These chips hold the processor output data to be sent to the external devices are called latches
Buffers
What are Buffers?
Devices for temporary storage.
Processor does not directly handle devices like keypads, switches, etc since they are very slow.
When processor needs to obtain data from such external devices we use Octal buffers to read data from the external devices onto the common data bus.
Crystal
The CPU needs a clock source, and a crystal oscillator generates the clock. You need to choose the crystal based on the clock frequency of the processor. Many micro-controllers provide an on-chip oscillator, and you connect an external crystal or ceramic resonator. The clock generation circuitry determines the various states of the machine cycle.