This document provides an overview of embedded C and embedded software architecture. It discusses topics such as memory usage, development environments, interrupts, keywords, and embedded system concepts. It also provides examples of a GPIO module and UART module. Interactive questions are included about topics like maskable interrupts, interrupt timing, and the differences between functions and macros.

1. By: Mostafa El-koumy
Day #1
Embedded

2. Introduction
?
o Introduction to Embedded C.
o Embedded Software Architecture.
o Memory usage.
o Embedded Development Environment.
o Interrupts.
o Keywords.
o Some Embedded Systems concepts.
By: Mostafa El-koumy

3. INTRODUCTION
 Embedded Systems is all things around you which have
something called electronic brain to make some sort of
artificial intelligence.
 Embedded C is a prober subset of C language suitable for
Embedded systems, it defines only a new concept of
writing software.
 Using Embedded C, we should handle everything used in
the program like Memory Management, HW Registers,
interrupts, …. Etc.
By: Mostafa El-koumy

4. MISRA RULES
 Motor Industry Software Reliability Association.
 Collaboration between engineering consultancies which
seeks to promote best practice in developing
Automotive Systems and other embedded systems.
 To this end MISRA publishes documents that provide
accessible information for engineers and management,
and holds events to permit the exchange of experiences
between practitioners.
 URL : www.misra.org.uk
 EX:
By: Mostafa El-koumy

5. EMBEDDED SOFTWARE ARCHITECTURE
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6. EMBEDDED SOFTWARE ARCHITECTURE (CON’T)
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7. CODE FLOW
 All the code is running within infinite loop in main except:
 Initialization code.
 Interrupt handlers, interrupt service routines (ISR).
 The other code runs normally
int main (void)
{
intitializeModule();
sei();
while(1){
startApplication();
}
return 0;
}
By: Mostafa El-koumy

8. BACKGROUND/FOREGROUND TASKS (LOW COST)
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9. SOFTWARE MODELING
Function
C file
Module
Project
C file(s) H file(s)
SW
module
Uart.c
Uart.h
Uart_irq.c
Uart_cfg.h

10. MEMORY USAGE BY LINKER SCRIPT
 The HW Registers
 Stack space that grow down
 Local variables
 Functions return address
 Heap Space that grow up
 Zero default initialized variables
 Initialized with value by developer
By: Mostafa El-koumy
I/O Addresses
Stack (grow down)
Heap (Grow up)
Un-initialized data
(.BSS)
Initialized data

11. DEVELOPMENT ENVIRONMENT
 IDE which has
 Text editor.
 Cross compiler produce machine language
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12. DEVELOPMENT ENVIRONMENT
 Development Kit
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13. DEVELOPMENT ENVIRONMENT
 In circuit Debugger (ICD)
 HW device connects to the microprocessor using JTAG/SWD
interface to support external control of the microprocessor
using debugger.
 Restrictions of debugging capabilities is specified by the
microprocessor.
By: Mostafa El-koumy

14. DEVELOPMENT ENVIRONMENT
 In circuit Emulator (ICE)
 HW device used to debug embedded SW. it replaces the
microprocessor with control over all the aspects of it and it
usually emulate all the microprocessor family.
By: Mostafa El-koumy

15. PROGRAMMING PROCESS DIAGRAM
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16. GPIO MODULE
Exercise
1
By: Mostafa El-koumy

17. INTERRUPTS
 an interrupt is a signal to the processor emitted by
hardware or software indicating an event that needs
immediate attention. An interrupt alerts the processor
to a high-priority condition requiring the interruption of
the current code the processor is executing.
 Interrupt sources
 Internal peripherals.
 External interrupts.
 SW interrupts.
 Exception thrown by processors.
By: Mostafa El-koumy

18. INTERACTIVE QUESTIONS
 Mask able interrupt?
 Non-Mask able interrupts?
 Level triggered external interrupt?
 Edge triggered external interrupt?
 Interrupt nesting?
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19. INTERRUPT TIMING
 Interrupt latency?
 Context?
 Interrupt response?
 Interrupt recovery?
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20. EMBEDDED KEYWORDS (INTERACTIVE)
 Scope and life time with keywords:
 Static local
 Static global
 Volatile
 Const
 Extern
 register
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21. FUNCTIONS VS MACROS
 Macros in completely text replacement so it increase the
code size and duplications.
 Function is preferred.
By: Mostafa El-koumy

22. MACROS VS INLINE FUNCTIONS
 In Inline functions Compiler substitute the function call
by function code like MACROS.
 MACROS is supported by preprocessor so all the IDEs
supports it.
 Inline is supported by some compilers.
 Inline function performs type checking but MACROs not.
 Inline function could be traced but MACROs not.
 Some compiler disable inline function when the its code
is large.

23. Exercise
2
By: Mostafa El-koumy
UART MODULE

24. Thank you for
your attention!
Any Questions?
By: Mostafa El-koumy

25. CONTACT DETAILS
 Mostafa El-koumy
 Embedded SW Developer
 mostafa.elkoumy@gmail.com