Write a program to echo the string, Computer Engineering

Assignment Help:

Write a program to echo the string 'Hello' to the serial channel (SCI) using the protocol of baud rate 9600,8 bits , no parity and 1 stop bit 

Consider the baud register as shown below

2169_Write a program to echo the string.png

Using a combination of bits5,4,2,1,0 we can set up the required baud rate .On the target system provided the input clock crystal is a 8Mhz (2Mhz internal E) version , therefore for a baud rate of 9600 is the easiest one

      Bit 5= 1 Bit 4 = 1 Bit 2 = 0 Bit 1 = 0 Bit 0 = 0

i.e. (2Mhz / 13) = 9600 *8 bits per second i.e. 9600 Baud

          Baud = 0x30

The bit length mode is set by bit 4 of the SCCR1 as shown below

1494_Write a program to echo the string1.png

 

    Bit = 0 'Start bit 8 data bits 1 stop bit'
    Bit = 1 'Start bit 9 data bits 1 stop bit '

Therefore bit 4 of sccr1 = 0    Sccr1 = 0x00

The SCI control 2 enables us to set interrupts if data is received or can be transmitted; in this case we simply want to enable the transmitter and receiver  
      
Therefore

2071_Write a program to echo the string2.png

 
    TE Bit 3, 2= 1
 
    Sccr2 = 0x0c 

 

This completes the SCI set-up, the remaining register is useful in determining whether data is received or can be transmitted

1310_Write a program to echo the string3.png

We can simply check bit7  if this is '1' we can send more data ,Since the configuration is actually set-up on the development boards we do not need to re-program the baud rates but simply use the comms channel. Therefore the a simple hello display program follows

  name ex6  ;Use of the uart to echo Hello ten times
baud  equ $2b ;Baud rate  register
sccr1  equ $2c  ;SCI control 1
sccr2  equ $2d ;SCI control 2
scsr  equ $2e  ;SCI status
scdr  equ $2f  ;Serial data register
  org $500  ;Start on external ram
;Note that the uart is configured by the monitor
;the following codes are used for eprom use
; sccr1 = 0 hex (No 9th bit)
;baud = 30 Hex (9600 using  8Mhz xtal )
; sccr2 = 0c hex (Enable tx)
  ldx #$0a  ;load up Counter with 10
loop  ldaa #'H'  ;load up ASCII H
  jsr txd    ;Send data
  ldaa #'e'  ;Load up ASCII e
  jsr txd    ;Send data
  ldaa #'l' ;Load up ASCII l
  jsr txd    ;Send data
  ldaa #'l' ;Load up ASCII l
  jsr txd    ;Send data
  ldaa #'o'  ;Load up ASCII o
  jsr txd    ;Send data
  ldaa #$0a  ;Load up ASCII newline
  jsr txd    ;Send data
  ldaa #$0d  ;Load up ASCII return
  jsr txd    ;Send data
  dex    ;X=X-1
  bne loop  ;repeat till zero
  swi    ;return back to monitor
txd  ldab scsr  ;Get sci status
  andb #$80  ;Mask off bit 7 TDRE
  beq txd  ;Wait till ready to transmit
  staa scdr  ;send data from A out
  ldy #$ff  ;Software time delay
loop1  dey    ;instead of XON/XOFF protocol
  bne loop1  ;wait till y = 0
  rts
  end


Related Discussions:- Write a program to echo the string

Explain about indirect addressing, Q. Explain about Indirect Addressing? ...

Q. Explain about Indirect Addressing? In this technique the operand field of instruction specifies the address of address of intended operand for example if instruction LOAD

A switch statement , Which is more efficient, a switch statement or an if e...

Which is more efficient, a switch statement or an if else chain? Ans) The differences, if any, are likely to be small. The switch statement was designed to be efficiently impl

Generation of erp products, 1. How does this new generation of ERP products...

1. How does this new generation of ERP products differ from traditional solutions? 2. What are the major external forces driving competition in the ERP industry? Cloud comput

State about the directed-test methodology, Directed-Test Methodology Bu...

Directed-Test Methodology Building a directed verification environment with a comprehensive set of directed tests is very time-consuming and difficult. As directed tests only c

State the scope of security policy, State the scope of security policy ...

State the scope of security policy The scope of security policy depends on aspects such as the size of the Intranet site, type of information hosted on it, and the number of u

Collective communications - broadcast, Q. Collective Communications - Broad...

Q. Collective Communications - Broadcast? Broadcast: Broadcasting can be done in two ways one of them is one to all and another one is all to all. In the matter of one to all b

Super class and subclass in programming, What is the difference among super...

What is the difference among super class and subclass in programming? Ans) A super class is a class that is inherited in programming while the sub class is a class that does th

Explain types of micro-instructions, Q. Explain types of Micro-instructions...

Q. Explain types of Micro-instructions? In general micro-instruction can be classifiedin two general kinds. These are non-branching and branching. After execution of a non-bran

Explain user datagram protocol, Explain User Datagram Protocol. UDP(Use...

Explain User Datagram Protocol. UDP(User Datagram Protocol) : User Datagram Protocol uses a connectionless communication paradigm. It is an application using UDP does not re

Implementation of arithmetic circuits, Implementation of Arithmetic Circuit...

Implementation of Arithmetic Circuits for Arithmetic Micro-operation  An arithmetic circuit can be implemented by a number of full adder circuits or parallel adder circuits. F

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd