Keil C51 Cross Compiler - gmitWEB

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Generating Delays • Software Delays – Uses looping mechanisms in C or assembly – Does not use any microcontroller hardware resources – Ties up the CPU while the delay is running – Delay produced depends on the compiler • Hardware Delays – Uses a microcontroller timer – Uses very little CPU resources (runs in background) Embedded Systems 2 2 - 24 C Programming
Software Delay • Use a for loop – Does not use any timer resources – Uses CPU resources while running • i.e. no other task can be performed during delay loop – Can result in large amounts of machine code being generated – Results may be different for different compilers • The following code results in a 204 usecond delay for the 8051 operating off the 12MHz oscillator • For loops can be nested to produce longer delays void delay() { unsigned char x; for (x=100; i > 0; x--); } Embedded Systems 2 2 - 25 C Programming
Page 1 and 2: Keil C51 Cross Compiler • ANSI C
Page 3 and 4: C51 Keywords Embedded Systems 2 2 -
Page 5 and 6: C51 Memory Models • Small - All v
Page 7 and 8: C51 Memory Types • Memory type ex
Page 9 and 10: C51 Memory Types • bdata - Bit ad
Page 11 and 12: Example Code (1) sbit input = P1^0;
Page 13 and 14: Wait Loops • In some applications
Page 15 and 16: C Bitwise Operators • NOT ~ char
Page 17 and 18: C Logical Operators • Bitwise ope
Page 19 and 20: Accessing Port Pins • Writing to
Page 21 and 22: Example Code (3) //Program to read
Page 23: Example Code (4) //program to flash
Page 27 and 28: Hardware Delay • Use timer 0 or t
Page 29 and 30: Re-entrant Functions • A re-entra
Page 31 and 32: Function Parameter Passing • Up t
Page 33 and 34: Interrupt Functions • Interrupt v
Page 35: C51 Pointers • Generic pointers -

Keil C51 Cross Compiler - gmitWEB

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