Laboratory $5\mathrm{.}1$ Password Check using Serial Port Polling

The objective of this laboratory is to get students familiar with the MC$8051$ serial port operation.

The program prompts the user to enter password $$Please Enter Password$.$ The entered characters

sequence is compared to the correct password $$CS$343.$ Every entered character is echoed back

as an $$X$$ ASCII. After receiving the five required characters, the prompt message is repeated if

the password is incorrect. Otherwise the program continues a main task repetition including

reading port P$1$ and displaying its complement on P$2.$

$164$

The Keil simulator uses the following:

$$ An $8\_$bit UART for characters entry and display.

$$ The BAUD is $9600$ for both reception and transmission.

$$ Polling is used for the TI and RI flags of the serial port.

$$ The program decides on the password correctness only after all five characters are received

and verified.

$$ Entered characters are echoed back as $$X$$ in order to hide where mistakes are made.

$$ Message display must insure that the curser is positioned on a new line.

$$ A message termination character $$$$$ is used to mark the end of the message.

$$ The two messages are stored in code memory.

Laboratory $5\mathrm{.}3$ BCD Temperature Conversion

Objectives: Upon completion of this laboratory, you will be familiar with FRD $($convert from

BCD$)$ and TOD $($convert to BCD$)$ instructions and comparison instruction $($Greater than or equal$)$

and its use within the ladder logic to control a process.

Figure $5\mathrm{.}42$ BCD I$/$O LogixPro HMI$*$

$*$Simulator courtesy of The Learning Pit LogixPro $500$

Process Description: Design and implement an assembly program to perform the conversion from

positive two digits degree Fahrenheit $($F$)$ to the equivalent degree Centigrade $($C$).$ The degree F is

limited to BCD digits $(00$ to $99).$ The formula for the conversion is given by the following

equation:

C $=($F $-32)*5/9$

Laboratory Requirements:

$1.$ Design the specification for the temperature conversion assuming a two decimal digits

entry through the serial port interface at BAUD $19200$ bps$.$

$166$

$2.$ Characters reception and transmission utilizes the serial port interrupt and the RS$232$ serial

interface.

$3.$ The user is prompted to enter the two digits degree Fahrenheit $$Please Enter the Two Digits

Degree Fahrenheit$.$

$4.$ The program does the conversion calculation and display the answer message $$The

Equivalent Degree Centigrade is $+/-$ xx$.$

$5.$ Main program task stays the same as rigure $3\mathrm{.}42$ DLD I$/$U LogixFro HIVI

$*$Simulator courtesy of The Learning Pit LogixPro $500$