Embedded Systems Architecture, Programming and Interfacing Guide
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The document discusses various topics related to embedded systems and microcontrollers including: - Architectures like Von Neumann, Harvard and modified Harvard - Types of microcontrollers like 8-bit, 16-bit and 32-bit - Programming languages and IDEs used for embedded programming - Common development boards and microcontrollers - Memory types, buses, I/O and basic operation of microcontrollers - Interfacing sensors and actuators to microcontrollers
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Embedded Systems Architecture, Programming and Interfacing Guide
- 4. Architectures: – Von Neumann – Harvard – Harvard modified
- 5. Microcontroller 8 bit 16bit 32bit,etc. Digital Signal Processor Digital Signal Controller FPGA/ASIC-Programmable Logic SoC-Processor System & Programmable Logics
- 6. Arduino IDE Energia Python IDE IAR workbench Keil CCS Xilinx ISE/Vivado web edition
- 7. Arduino Raspberry Pi 8051 development board PIC development board Tiva C series STM32F4 Many more…..
- 8. There are different programming styles available to use or we can create it by mixing one in another. Standards available languages are: ◦ Assembly level: Board specific ◦ Embedded c: Generalized with common instructions
- 9. C/C++ Embedded C Python VHDL Verilog MATLAB Simulink
- 10. External Memeories RS232 CAN LAN(RJ45) SPI I2C PCI PCIe Other networking protocols
- 11. Temperature sensor module Vibration switch module Hall magnetic sensor module Key switch module Infrared emission sensor module Small passive buzzer module Laser sensor module 3-color full-color LED SMD modules Optical broken module Etc..many more available on: https://tkkrlab.nl/wiki/Arduino_37_sensors
- 12. Unsigned Integers ◦ All eight bits represent the magnitude of a number Bit7 to Bit0 ◦ Range 00H to FFH (010 to 25510) 12
- 13. Signed Integers ◦ 2's Complement Bit7 is sign bit ◦ Positive numbers: 00H to 7FH (010 to 12710) ◦ Negative numbers: 80H to FFH (-110 to -12810) 13
- 14. Binary Coded Decimal Numbers (BCD) ◦ 8-bit number divided into two groups of four Each group represents a decimal digit from 0 to 9 ◦ AH through FH are invalid ◦ Example: 0010 0101BCD = 2510 14
- 15. American Standard Code for Information Interchange (ASCII) ◦ 7-bit alphanumeric code with 128 combinations (00H to 7FH) ◦ Represents English alphabet, decimal digits from 0 to 9, symbols, and commands 15
- 16. Which is easy? Assembly Language Embedded C Language
- 19. Meeting the computing needs of the task efficiently and cost effectively Speed, the amount of ROM and RAM, the number of I/O ports and timers, size, packaging, power consumption Easy to upgrade Cost per unit Availability of software development tools Assemblers, debuggers, C compilers, emulator, simulator, technical support Wide availability and reliable sources of the microcontrollers.
- 20. A Harvard Architecture (separate instruction/data memories) Single chip Microcontroller(µC) Developed by Intel in 1980 for use in embedded systems. Today largely superseded by a vast range of faster and/or functionally enhanced 8051-compatible devices manufactured by more than 20 independent manufacturers
- 21. Feature 8051 8052 8031 ROM (program space in bytes) 4K 8K 0K RAM (bytes) 128 256 128 Timers 2 3 2 I/O pins 32 32 32 Serial port 1 1 1 Interrupt sources 6 8 6 Comparison of the 8051 Family
- 23. 23
- 24. MPU (CPU) ◦ Read instructions ◦ Process binary data 24
- 25. Storage Device ◦ Addresses ◦ Registers Major Categories ◦ Read/Write Memory (R/W) ◦ Read-only-Memory (ROM) 25 D7 D0
- 26. Input Devices ◦ Switches and Keypads ◦ Provide binary information to the MPU Output devices ◦ LEDs and LCDs ◦ Receive binary information from the MPU 26
- 27. MPU communicates with Memory and I/O using the System Bus ◦ Address bus Unidirectional Memory and I/O Addresses ◦ Data bus Bidirectional Transfers Binary Data and Instructions ◦ Control lines Read and Write timing signals 27
- 28. 28
- 29. Machine Language ◦ Binary Instructions ◦ Difficult to decipher and write Error-prone ◦ All programs converted into machine language for execution 29 Instructio n He x Mnemoni c Description Processor 1000000 0 80 ADD B Add reg B to Acc Intel 8085 0010100 0 28 ADD A, R0 Add Reg R0 to Acc Intel 8051 0001101 1 1B ABA Add Acc A and B Motorola 6811
- 30. Assembly Language ◦ Machine instructions represented in mnemonics ◦ One-to-one correspondence ◦ Efficient execution and use of memory ◦ Machine-specific 30
- 31. High-Level Languages ◦ BASIC, C, and C++ ◦ Written in statements of spoken languages ◦ Machine independent ◦ Easy to write and troubleshoot ◦ Larger memory and less efficient execution 31
- 33. RISC CPUs ◦ 8-bit ◦ 16-bit Number of I/O pins: 4-70 Memory types and sizes: ◦ Flash; OTP; ROM ◦ 0.5k – 256k
- 34. 5/6 Programming pins 8 A/D channels 2 Oscillator Inputs 2 RS-232 inputs 33 I/O ports
- 35. Download @ http://microchip.com Assembly compiler for programming PICs Based on specific PIC instruction set
- 36. PIC: Elements of a digital controller CPU Central Processing Unit Input Peripherals Output Peripherals ROM Read Only Memory RAM Read & Write Memory Program download User input User output The microcontroller contains all these elements in one chip
- 37. 16F877 pin-out The microcontroller pins have multiple functions
- 38. Screenshot of MPLAB Project The C program is compiled and tested in simulation mode
- 40. ARM
- 41. Developed at Acorn Computers Limited, of Cambridge, England, between 1983 and 1985 Problems with CISC: Slower then memory parts Clock cycles per instruction 41
- 42. Typical RISC architecture: Large uniform register file Load/store architecture Simple addressing modes Uniform and fixed-length instruction fields 42
- 43. Enhancements: Each instruction controls the ALU and shifter Auto-increment and auto-decrement addressing modes Multiple Load/Store Conditional execution 43
- 44. Floating Point Processor-Ex.TMS320F28335 Fixed Point Processor-Ex.TMS320F6745
- 46. Simple logic gates ◦ combine transistors to implement combinational and sequential logic Interconnect ◦ wires to connect inputs and outputs to logic blocks I/O blocks ◦ special blocks at periphery for external connections Add wires to make connections ◦ done when chip is fabbed “mask-programmable” ◦ construct any circuit
- 47. Logic blocks ◦ to implement combinational and sequential logic Interconnect ◦ wires to connect inputs and outputs to logic blocks I/O blocks ◦ special logic blocks at periphery of device for external connections Key questions: ◦ how to make logic blocks programmable? ◦ how to connect the wires? ◦ after the chip has been fabbed
- 48. Soft-core are available with FPGA /ASIC’s and SoC. ◦ ARM processor ◦ Microblaze processor
- 49. Implementation of random logic ◦ easier changes at system-level (one device is modified) ◦ can eliminate need for full-custom chips Prototyping ◦ ensemble of gate arrays used to emulate a circuit to be manufactured ◦ get more/better/faster debugging done than possible with simulation Reconfigurable hardware ◦ one hardware block used to implement more than one function ◦ functions must be mutually-exclusive in time ◦ can greatly reduce cost while enhancing flexibility ◦ RAM-based only option Special-purpose computation engines ◦ hardware dedicated to solving one problem (or class of problems) ◦ accelerators attached to general-purpose computers
- 50. Complete ARM®-based processing system ◦ Application Processor Unit (APU) Dual ARM Cortex™-A9 processors Caches and support blocks ◦ Fully integrated memory controllers ◦ I/O peripherals Tightly integrated programmable logic ◦ Used to extend the processing system ◦ Scalable density and performance Flexible array of I/O ◦ Wide range of external multi-standard I/O ◦ High-performance integrated serial transceivers ◦ Analog-to-digital converter inputs
- 52. The Zynq-7000 AP SoC architecture consists of two major sections ◦ PS: Processing system Dual ARM Cortex-A9 processor based Multiple peripherals Hard silicon core ◦ PL: Programmable logic digital logic design
- 54. Three basic modes: ◦ 1. Continuous dedicated monitoring of the sensor by the microprocessor ◦ 2. Polling the sensor ◦ 3. Interrupt mode
- 55. Microprocessor is dedicated for use with the sensor Its output is monitored by the microprocessor continuously The microprocessor reads the sensor’s output at a given rate Output is then used to act
- 56. Sensor operates as if the microprocessor did not exist. Its output is monitored by the microprocessor The microprocessor reads the sensor’s output at a given rate or intervals - poling Output is then used to act
- 57. Microprocessor is in sleep mode Outputs of the sensor are not being processed Upon a given event, microprocessor wakes up through one of its interrupt options The sensor activates the interrupt
- 58. Interrupts can be timed Interrupts can be issued by sources other than the sensor The microprocessor may be involved in other functions, separate from the sensor, such as control of an actuator Feedback from actuators may also be used to perform interrupts
- 59. Microprocessor input interfacing requirements Microprocessor output requirements Errors introduced by microprocessors
- 60. Signal level Impedance and matching Response, frequency Signal conditioning Signal scaling Isolation Loading
- 61. Signal levels Power levels Isolation
- 62. Basic level: zero to Vdd ◦ Must scale signals if necessary No dual polarity signals ◦ Must translate/scale as necessary Direct reading or A/D Can read voltages only ◦ AC or DC ◦ Limitations in frequency
- 63. P are high input impedance devices ◦ ~ 1 - 10 M ◦ Input current - < 1 A. Ideal for direct connection of low impedance sensors (magnetic, thermistors, thermoelectric, etc.) High impedance sensors (capacitive, pyroelectric, etc.) must be buffered ◦ Voltage followers ◦ FET amplifiers
- 64. Most sensors are slow devices ◦ Can be interfaced directly ◦ No concern for response and frequency range Some sensors are part of oscillators ◦ Frequencies may be quite high ◦ Need to worry about proper sampling by the microprocessor
- 65. Example: 10 mHz P, cycle time of 0.4 s. (most processor divide the clock frequency by a factor - 4 in this case) Any operation such as reading an input required n cycles, say n=5 Effective frequency: 0.5 MHz Sampling cannot be done at rates higher than 250 kHz Any sensor producing a signal above this frequency will be read erroneously
- 66. Some solutions: ◦ Divide the sensor’s frequency Reduces sensitivity Must be done externally to the P ◦ F-V converter Introduces conversion errors Must be done externally ◦ Frequency counter at input Use output of the counter as input to mP. Expensive ◦ Faster microprocessors
- 67. Offset ◦ Primarily for dc levels ◦ Can be offset up or down ◦ Usually done to remove the dc level ◦ Sometimes needed to remove negative polarity. ◦ AC signals may sometimes be coupled through capacitors to eliminate dc levels
- 68. Example ◦ Thermistor: 500 at 20ºC ◦ Varies from 100 to 900 for temp. between 0 and 100ºC
- 69. At 500ºC ◦ V = (12/1500)*500 = 4 V At 0ºC ◦ V = (12/1400)*400 = 3.428 V At 100ºC ◦ V = (12/1900)*900 = 5.684 V V varies between 3.428V and 5.684V ◦ 5.684V is above the 5V operating voltage of the microprocessor
- 70. Errors introduced by the microprocessor: ◦ Due to resolution of A/D, D/A ◦ Sampling errors These come in addition to any errors in the sensor/actuator
- 71. Most microprocessors are 8 bit microprocessors Integer arithmetics Largest value represented: 256 Roundoff errors due to this representation Special math subroutines have been developed to minimize these errors (otherwise they would be unacceptably high)
- 72. All inputs and outputs on a microprocessor are sampled. That is: ◦ Inputs are only read at intervals ◦ Outputs are only updated at intervals ◦ Intervals depend on the frequency of the clock, operation to be executed and on the software that executes it ◦ Sampling may not even be constant during operation because of the need to perform different tasks at different times ◦ Errors are due to changes in input/output between sampling to which the microprocessor is oblivious ◦ Errors are not fixed - depend among other things on how well the program is written
- 74. There are lots of application use microcontroller some of them are given below: ◦ CAR ◦ Refrigerator ◦ Airplane ◦ Trains ◦ Medical devices, etc. Some example will be explained in Last slides.
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- 76. 76
- 78. Microcontroller and Microprocessor Digital System Signal and System(Z transform and Filter Designing) Digital Signal Processing Networking Control system Basic analog design