Lab 3 experiment sheet

Lab 3: Digital Input
Lab 3: Digital Input
Objective
Now let’s add some digital input functions to our code. On the Zwickau Adapter
Board, the digital I/O lines GPIO-B15 to B8 are connected to 8 input switches.
When a switch is closed it will be red as digital ‘0’, if it is open as ‘1’.
The objective of Lab3 is to copy the status of the 8 switches to the 8 LED’s as the
only task of the main loop. Hopefully our DSP will not complain about the
simplicity of this task!
Lab 3: Digital Input (GPIO B15..B8)
Aim :
• 8 DIP-Switches connected to GPIO-Port B ( B15...B8)
• 8 LED‘s connected to B7...B0
• read the switches and show their status on the LED’s
Project - Files :
1. C - source file: “Lab3.c”
2. Register Definition File:
“DSP281x_GlobalVariableDefs.c
3. Linker Command File :
F2812_EzDSP_RAM_lnk.cmd
4. Runtime Library “rts2800_ml.lib
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Procedure
Open Files, Create Project File
1. Create a new project, called Lab3.pjt in E:\C281x\Labs.
2. Open the file Lab2.c from E:\C281x\Labs\Lab2 and save it as Lab3.c in
E:\C281x\Labs\Lab3.
3. Modify Lab3.c. Remove the lookup table “LED[8]”. Keep the function calls to
“InitSystem()” and “Gpio_select()”. Inside the endless while(1)-loop modify the
control loop as needed. Do you still need the for-loop How about the watchdog
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Lab 3: Digital Input
Remember, we served the watchdog inside “delay_function()” – it would be unwise
to remove this function call from our control loop!
4. Add the source code file to your project:
• Lab3.c
5. From C:\tidcs\c28\dsp281x\v100\DSP281x_headers\source add:
• DSP281x_GlobalVariableDefs.c
From C:\tidcs\c28\dsp281x\v100\DSP281x_common\cmd add:
• F2812_EzDSP_RAM_lnk.cmd
From C:\tidcs\c28\dsp281x\v100\DSP281x_headers\cmd add:
• F2812_Headers_nonBIOS.cmd
From C:\ti\c2000\cgtoolslib add:
• rts2800_ml.lib
Project Build Options
6. We need to setup the search path to include the peripheral register header files. Click:
Project Build Options
Select the Compiler tab. In the preprocessor Category, find the Include Search
Path (-i) box and enter:
C:\tidcs\C28\dsp281x\v100\DSP281x_headers\include;..\include
7. Setup the stack size: Inside Build Options select the Linker tab and enter in the Stack
Size (-stack) box:
400
Close the Build Options Menu by Clicking .
Build and Load
8. Click the “Rebuild All” button or perform:
Project Build
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Lab 3: Digital Input
and watch the tools run in the build window. If you get errors or warnings debug as
necessary.
9. Load the output file down to the DSP Click:
File Load Program and choose the desired output file.
Test
10. Reset the DSP by clicking on:
Debug Reset CPU
Debug Restart
followed by
11. Run the program until the first line of your C-code by clicking:
Debug Go main.
12. Start the code
Debug Run
and test the operation of your code. When you change the status of the switchline
you should see the new value immediately shown at the LED’s.
If not, your modification of the code (Step 3 of the procedure) was not correct. In
this case try to find out why by using the debug tools that you’ve learned about in
Lab1 (Breakpoint, Step, Watch Variables…).
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Lab 3A: Digital Input + Output
Lab 3A: Digital Input + Output
Objective
Now let’s combine Lab3 and Lab2! That means I’d like you to control the speed
of your “Knight Rider” (Lab2) depending on the status of the input switches.
Question: What’s the minimum / maximum value that can be produced by the 8
input switches Use the answer to calculate the length of function “delay_loop()”
depending on the input from GPIO B15...B8.
Lab 3A
“Knight - Rider” plus frequency control :
• modify Lab 2 :
• read the input switches ( B15-B8 )
• modify the frequency of the ‘running light’
(B7-B0) subject to the status of the input
switches, e.g. between 10sec and 0.01 sec per
step of the LED-sequence
• enable the watchdog timer !
• Verify that , ones your program is in the main
loop, the watchdog causes a reset periodically.
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Procedure
Create Project File
1. Create a new project, called Lab3A.pjt in E:\C281x\Labs.
2. Open the file Lab2.c from E:\C281x\Labs\Lab2 and save it as Lab3A.c in
E:\C281x\Labs\Lab3A.
3. Add the source code file to your project:
• Lab3A.c
4. From C:\tidcs\c28\dsp281x\v100\DSP281x_headers\source add:
• DSP281x_GlobalVariableDefs.c
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Lab 3A: Digital Input + Output
From C:\tidcs\c28\dsp281x\v100\DSP281x_common\cmd add:
• F2812_EzDSP_RAM_lnk.cmd
From C:\tidcs\c28\dsp281x\v100\DSP281x_headers\cmd add:
• F2812_Headers_nonBIOS.cmd
From C:\ti\c2000\cgtoolslib add:
• rts2800_ml.lib
Setup Build Options
5. We need to setup the search path to include the peripheral register header files. Click:
Project Build Options
Select the Compiler tab. In the preprocessor Category, find the Include Search
Path (-i) box and enter:
C:\tidcs\C28\dsp281x\v100\DSP281x_headers\include;..\include
6. Setup the stack size: Inside Build Options select the Linker tab and enter in the Stack
Size (-stack) box:
400
Close the Build Options Menu by Clicking .
Modify Lab3A.C
7. Modify the run time of function “delay_loop”. The input parameter of this function
defines the run time of the software delay loop. All you have to do is to adjust the
actual parameter using the GPIO-input’s B15…B8.
8. The best position to update the parameter for the delay loop time is inside the endless
loop of main, between two steps of the “Knight Rider” sequence.
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Lab 3A: Digital Input + Output
Lab 3A (cont.)
Serve the watchdog :
• do not disable the watchdog timer !
• Inside the main-loop execute the watchdogreset
instructions (WDKEY) to prevent the
watchdog timer from overflow.
• Place the software-delay in a function and
experiment with different delay period’s.
What is the period when the watchdog-timer
does reset the DSP
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9. Remember, it is always good practice to work with an enabled watchdog! Eventually
for a large parameter for the period of delay_loop() you will have to adjust your
watchdog good key sequence instructions to prevent the watchdog from causing a
RESET.
Build, Load and Test
10. Build, Load and Test as you’ve done in previous exercises.
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Lab 3B: Start / Stop Option
Lab 3B: Start / Stop Option
Objective
A last improvement of our Lab is to add a START/STOP option to it. The Zwickau
adapter board has two momentary push buttons connected to GPIO-D1 and GPIO-D6. If a
button is pushed, the input line reads ‘0’; if it is not pushed it reads ‘1’. The objective is
now to use D1 as a start button to start the ‘Knight Rider’ sequence and D6 to stop it.
• use Lab 2 to start:
Lab 3B
Add start/stop control:
• GPIO-D1 and D6 are connected to two pushbuttons.
If they are pushed, the input level
reads 0, if released 1.
• Use D1 to start the LED “Knight-rider” and
D6 to halt it. If D1 is pushed again the
sequence should continue again.
• To do so, you also need to add the instructions
to initialise GPIO-D
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Procedure
Create Project File
1. Create a new project, called Lab3B.pjt in E:\C281x\Labs.
2. Open the file Lab3A.c from E:\C281x\Labs\Lab3A and save it as Lab3B.c in
E:\C281x\Labs\Lab3B.
3. Add the source code file to your project:
• Lab3B.c
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Lab 3B: Start / Stop Option
4. From C:\tidcs\c28\dsp281x\v100\DSP281x_headers\source add:
• DSP281x_GlobalVariableDefs.c
From C:\tidcs\c28\dsp281x\v100\DSP281x_common\cmd add:
• F2812_EzDSP_RAM_lnk.cmd
From C:\tidcs\c28\dsp281x\v100\DSP281x_headers\cmd add:
• F2812_Headers_nonBIOS.cmd
From C:\ti\c2000\cgtoolslib add:
• rts2800_ml.lib
Setup Build Options
5. Project Build Options
Select the Compiler tab. In the preprocessor Category, find the Include Search Path (-
i) box and enter:
C:\tidcs\C28\dsp281x\v100\DSP281x_headers\include;..\include
6. Setup the stack size: Inside Build Options select the Linker tab and enter in
the Stack Size (-stack) box: 400
Close the Build Options Menu by Clicking .
Modify Lab3B.C
7. Take into account to modify the endless while(1) loop of main. The for-loop should
run after D1 is pushed and freeze when D6 is pushed. With the next D1 the procedure
should resume from its frozen status.
Build, Load and Test
8. Build, Load and Test as you’ve done in previous exercises.
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