r8c 11/13 application model r8c11/13-fe-a19frontline-electronics.com/downloads//demo6.pdf · 3 4...

14 Digit Stop Clock

R8C 11/13 Application Model R8C11/13-FE-A19

www.MightyMicons.com

Introduction:

This Demo discusses a complete application based on R8C11/13 microcontroller. The applica-

tion is based on a digital clock with the simple interaction. Four digits of seven segment LED

display are used to display the stop clock along with three switches for the operation.

Demo Hardware:

The hardware contains 4 digits of seven segment LED displays connected in the multiplexed

format. Three push button switches are connected to port lines to get Start, Stop and Clear

commands.

Port line Display LinesP00 BCD I/P A

P01 BCD I/P B

P02 BCD I/P C

P03 BCD I/P D

P04 Digit Selection Control for digit 1




Port line Push Button SwicthesP30 Start Switch

P31 Stop Switch

P32 Clear Switch

24 Digit Stop Clock



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34 Digit Stop Clock



Connections:

1. Connect port lines P00 to P03 to BCD inputs of seven segement display.

2. Connect port lines P04 to P07 to digit selection input of seven segment display.

3. Connect port lines P30 to P32 to three push button switches.

Functional Description:

In this module, a complete project for the 4 digit stop clock is provided. 4 digits of seven segment

display are used for displaying the seconds and 3 numbers of push button switches are used to

give Start, Stop and Clear commands. The seven segment display is used in multiplexed mode

with BCD input.

Timer X of the R8C Tiny is used to generate an interrupt at a rate of one milli second. In the timer

X interrupt service routine, the LED display is refreshed and the milli seconds are counted to get

one second delay for counting the seconds after the start command from the user.

Registers Used:

PD0 - Port 0 Direction Register

PD3 - Port 3 Direction Register

TXMR- Timer X mode register

PREX- Prescaler X Register

TX - Timer X Register

TCSS- Timer count source setting register

44 Digit Stop Clock



Port Pi Direction Register:

PD0 is set to H’FF to select all lines of port 0 (P00 to P07) as output lines to control the seven

segment display. The port 3 lines P30 to P32 are selected as input lines after the reset.

Timer X Mode Register:

Timer X mode register TXMR is loaded with H’00 to set the timer mode.

54 Digit Stop Clock



Prescalar X Register

The prescaler register PREX is loaded with 100 to divide the selected clock meant for the timer

X.

Timer X Register

The timer X register TX loaded with 100 to generate an interrupt at 1 milli second rate.

64 Digit Stop Clock



Timer Count Source Setting Register.

The data H’03 is moved to Timer Count Source Setting Register TCSS to select “f2” as source

clock for Timer X.

Software Description:

In the main loop, two types of operations are carried out according to the clock status. If the

clock is in active running condition, only stop swicth was enabled during switch scanning to

issue a stop command. In the active stop clock condition, clear command is disabled. When the

clock is stopped, the start and clear switches are enabled to get start and clear commands.

After the start command, the clock running variable is set to clock running state and after the

clear command, the variable holding the seconds count will be cleared to 0.

The files used in this module are listed below:

Files Description

R8C1113_FE_A19.C

The only file for this module, has the processing function for the stop clock, timer X interrupt

service routine and initialization routines for seven segment

display, timer X etc.

74 Digit Stop Clock



The functions in the file R8C1113_FE_A19.C and short descriptions are listed below:

Files Description

ProcessStopClock

Checks the Start, Stop and Clear switch status and starts the stop clock or stops the stop clock or clears

the clock contents. Displays the counted seconds after start command.

Inpu

ProcessTimer_X_Int

Timer X interrupt service routine. Here the seven segment display was refreshed and the milli seconds are counted to get one second delay. The seconds are counted after

the start of the stop clock.

InitializeTimerX

Timer X is initialized to generate an interrupt at a rate of one milli second.

Input: None. Output : None.

InitializeSevenSegmentLED

This routine will initialize I/O lines used for seven segment display, Timer X and variables used for

refreshing display. Input: None. Output : Non

Display4Digits

Displays the given 4 digit number on seven segment display.

Input: 4 Digit number. Output : None.

BCDIncrement

Increments the given 4 digit number by one in BCD format and returns the same to called function.

Input: 4 Digit number. Output : Incremented value of given nu

InitializeSevenSegmentLED

This routine will initialize I/O lines used for seven segment display, Timer X and variables used for

refreshing display. Input: None.

Output :

Display4Digits

Displays the given 4 digit number on seven segment display.

Input: 4 Digit number. Output : None.

BCDIncrement

Increments the given 4 digit number by one in BCD format and returns the same to called function.

Input: 4 Digit number. Output : Incremented value.

84 Digit Stop Clock



Program Flow:For Main Loop

Start

1. I n i t ia l i ze Por t 0 asoutput port.

2. Initialize variables to 0.

3. Ini t ia lize Timer X togenerate an interrupt at1 msec rate.

Is there is any changein the time counter?

Display the new value oftime counter on LED

Is the Clock is inRunning State?

Yes

No

Yes

NoIs the Stop button

Pressed?

No

YesIs the Start Button

Pressed?Yes

No

Is the Clear ButtonPressed?

Yes

No

Clear milli seconds countvariable and Start the

stop clock.

Clear time count variableand update display with

new value.

Stop the Clock.

94 Digit Stop Clock



For Timer X Interrupt Service Routine

Start

Get the lower 2 bitsof digit selection

variable (MuxData).(Only 4 digits)

Switch off all thedigits

Send the BCD data anddigit selection data of thecurrently selected digit to

port 0.

Increment the currentlyselected digit

variable.(MuxData)

Is the stop clock isin running State?

Return from Interrupt

No

Yes

Update time count for thestop clock

1 04 Digit Stop Clock



Execute Demo:

After reset, the stop clock starts showing its initial value 0000. The program will wait for start

command from the user. After the start command, the clock will start counting the time and

displayed in four digits from 0000 to 9999 seconds. When the stop button is pressed, the clock

will be stopped and the display will show the current time count. The time count will be cleared

to 0000 if the clear button is pressed when the clock is in stop condition.




Use Topview Simulator to Verify the Design.

Open the project Demo4 in the R8C/Tiny System Simulator using Open Project option from

Project menu. The project window opens up along with the Demo4.c file. Use Build option from

Build menu to compile the project. An output window captures the compiler ouput.

Use Project -> Download Project from main menu to download the Demo4.mot file into the

simulator’s memory for simulation.

Open the LED Module settings window and do the settings to the 7-segment LED module as

shown. Connect BCD input of the display to the port lines P00 to P03 and the 4 digit selection

lines to P04 to P07 respectively.




Open the Keybaord Module settings window and do the settings. Connect the rows to P14 to

P17 and columns to P10 to P13.




Then open the LED window usign the option View -> External Modules -> LED as shown

below and the Program Window. Open the Keybaord window usign the option View -> ExternalModules -> Keyboard as shown below and the Program Window.




Run the program using Go from the Run menu.

After reset, the stop clock starts showing its initial value 0000. The program will wait for start

command from the user. After the start command, the clock will start counting the time and

displayed in four digits from 0000 to 9999 seconds. When the stop button is pressed, the clock

will be stopped and the display will show the current time count. The time count will be cleared

to 0000 if the clear button is pressed when the clock is in stop condition.

r8c 11/13 application model r8c11/13-fe-a19frontline-electronics.com/downloads//demo6.pdf · 3 4...

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