Microprocessors lesson 3 IO port, delays'

1
Microprocessors
lesson 3 I/O port,
delays.
2
Topics lesson 3

• Questions / remarks
• Consolidation
• Organisation
• Logbook
• CC5x compiler users manual
• Preparation
• MPLab C-compiler
• Architecture Clock
• PICkit1 board
• Architecture
• PC definition
• Memory map
• Presentation
• I/O port
• LEDs
• PICkit1 board (hardware)
• Lab Problem 1
• Next week (3th hour)
• Delays introduction

3
Device overview
Memory map
4
Program memory map
5
Memory organisationData
Memory map
6
Hardware description (LEDs)
7
Digital I/O (1)
FromReference Manuals for the mid-range MCU
Family (document 33023a)
My first problem
8
Digital I/O (2)port code snip
/example set RA4 as digital output,
low level/ void initDIO() //see data sheet for
values ANSEL ?? CMCON0 ?? void
LED0() PORTA0x3F//reset all latches
TRISA0b.1110.1111//RA4 as output
PORTA0b.0001.0000// RA 4 High
9
Design programs in C

• See CC5X users manualextensions and limitations
• Registers are predefined variables.PIC16Fxxx.H
  file
• Problems with simulation

10
Presentations

• LEDs
• I/O ports basics

11
Lab

• Problem 1see description

12
Self tuition for next week

• Also see preparation lesson 4
• Finish Problem 1
• Logbook evaluation
• Start Problem 2
• Presentation about TIMER0

13
Delay introduction

• Software
• Using clock cycles
• loop elements
• Hardware
• Timer device,
• polling based
• interrupt based.

14
Delay(3) Software

• Advantage easy to program
• Disadvantage Difficult to make a exact time
  delay
• Disadvantage processor is busy in delay loop.

15
Delay(2) software
//code snip Simple Loop uns z z0 Action()
while (zlt1270) //1270 is an example z
//Additional dummy statements //will make
the delay longer
16
Delay(4) HardwareTimer module

• Separate hardware module.
• Easy to calculate.
• Advantage processor is free during timer count.
  Clock cycles free for other activities

17
Delay (5) Hardware Timer 0
8-bit timer/counter Readable and writable
8-bit prescaler (software programmable)
Internal or external clock select Interrupt
on overflow Edge select for external clock
18
Problem 2

• Design and implement a running light
  (LED0..LED7).
• Software based on a loop.
• Hardwarebased on TIMER 0

19
Logbook evaluation