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- Lab 2 - programming the msp430
- Lab 2: c and macros with ti's
Programming basic C on an embedded processor.
With the MSP430, With the MSP430, the primary difference between "normal" C and programming C in the embedded space is that you will need to write to registers directly to control the operation of the processor. Fortunately, the groundwork has already been laid for you to make this easier. All of the registers in the MSP430 have been mapped to macros by Texas Instruments. Additionally, the important bit combinations for each of these registers have macros that use the same naming convention as the user’s guide. Other differences from the C used on most platforms include:
- Most registers in the MSP are 16 bits long, so an
int value is 2 bytes (16 bits) long.
- Writing to registers is not always like writing to a variable because the register may change without your specific orders. It is always important to read the register description to see what the register does.
- The watchdog timer will automatically reset the MSP unless you set the register not to.
- There is only a limited "standard out" system. Standard out will typically print results to your computer screen. The board you have been provided does have 7 segment displays and LED’s but this does not allow for a full debugging display that a PC would have.
- Floating-point operations cannot be efficiently performed. In general, you should avoid floating point decimal calculations on the MSP because it does not have special hardware to support the complicated algorithms used.
Code review
In this exercise, you may want to use some of the debugging tools to help you understand what the code is doing. You may use any of the following items:
-
Breakpoints - Left click on the arrow next to the line of code you want to break on. The program will stop when it gets to this point and you are able to view the contents of memory and current variable contents.
-
Watch Window - Right click on the variable you want to monitor and select
Add "variable" to Watch . Variables that have been modified since the last time that the program was stopped will turn red.
-
Locals Window - From the
View menu, click
Other Windows then
Locals . The Locals Window will automatically display the values for all local variables that are currently being used. Variables are considered "local" if they are within the function that is currently being processed.
Start a new project. Cut and paste the following code into main.c:
#include <msp430x16x.h>
#include <__cross_studio_io.h>
void main(void){
int i,j,tmp;
int a[20]={0x000C,0x0C62,0x0180,0x0D4A,0x00F0,0x0CCF,0x0C35,0x096E,0x02E4,
0x0BDB,0x0788,0x0AD7,0x0AC9,0x0D06,0x00EB,0x05CC,0x0AE3,0x05B7,0x001D,0x0000};
for (i=0; i<19; i++){
for (j=0; j<9-i; j++){
if (a[j+1] < a[j]) {
tmp = a[j];
a[j] = a[j+1];
a[j+1] = tmp;
}
}
}
while(1);
}
- Explain what this program is doing.
- Use any of the methods listed above to show the updated array. What is the final result?
- Modify the code so that it prints the final version of the array to standard out (the display window). What are the drawbacks and benefits of using this over setting a breakpoint?
To use the standard out, add the following line to the top of your code:
#include<__cross_studio_io.h> The
debug_printf() function will print to standard out. For example,
debug_printf("x equals %d\n", x); will print out the value of x to the window. The
%d means that x is a number, and
\n will produce a line break.
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Functions
Multiplications and division are very complex operations to do on any microprocessor. The operations should be avoided if possible or should be replaced with simpler, equivalent operations.
- What do the operators<<and>>do?
- How could you use these operators to perform multiplication and division?
- Write the function
multiply(int x, int y) that takes parameter
x and multiplies it by
y by using a bit shift. It must return an
int . For symplicity, it is OK to assume that
y is a power of 2.
- Next, write the function
divide(int x, int y) that takes parameter
x and divides it by
y by using a bit shift. It must also return an
int .
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Digital i/o registers
Open the file
msp430x16x.h which should be located in
C:\Program Files\Rowley Associates Limited\CrossWorks MSP430 x.x.x\include . This file contains the macros and register definitions for the MSP430F169 we use in this class. Using the
MSP430 User’s Guide and the msp430x16x.h file, please answer the following questions.
- The Watchdog Timer will automatically reset the hardware if it isn't periodically reset or disabled entirely. Usually, we will simply disable it. It can be disabled by writing to the
WDTPW (watchdog timer password) and
WDTHOLD (watchdog timer hold) section of the Watchdog Timer Control Register (
WDTCTL ). Refer to
Section 10.3 of the
User's Guide for more information. Find the macros for this register in the msp430x16x.h file. How are they different from their description in the User's Guide? Finally, write the C code required to disable it.
- What are the differences among P1DIR, P1SEL, P1OUT, P1IN?
- Some port pins have multiple functions to output and it is up to the user to select the appropriate signal. Write some code that would select the alternate function of P2.2 (pin 2 of port 2). What will the result be on our hardware?
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Programming digital i/o
Write a program to do the following:
- When the program starts all three LED’s should light up for about a second then turn off.
- Next, the green LED should blink for about 1/2 second on, 1/2 second off while the other two LED’s are off. Use long for-loops to generate a delay.
- Pushing Button 1 should cause the green LED to stop blinking and cause the red LED to start the blinking pattern.
- Pushing the button again should continue the pattern with the yellow LED, and pushing it more times should repeat the green, red, yellow pattern.
- The current LED that's blinking should stop as soon as the button is pressed and the next LED should begin immediately.
Make sure you disable the watchdog timer at the very beginning of the program. Refer to
Introduction to programming the MSP430 to learn how to enable and use the pushbuttons and LEDs.
You will need to demonstrate this code to the labbie, turn in a hard copy of your program, and post it online.
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Questions & Answers
What are the factors that affect demand for a commodity
differentiate between demand and supply
giving examples
differentiated between demand and supply using examples
Lambiv
how is the graph works?I don't fully understand
hi guys good evening to all
Lambiv
In economics, a perfect market refers to a theoretical construct where all participants have perfect information, goods are homogenous, there are no barriers to entry or exit, and prices are determined solely by supply and demand. It's an idealized model used for analysis,
Ezea
other things being equal
AI-Robot
When MP₁ becomes negative, TP start to decline.
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of lab
Kelo
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of labour (APL) and marginal product of labour (MPL)
Kelo
Can I ask you other question?
Shukri
What is different between quantity demand and demand?
Quantity demanded refers to the specific amount of a good or service that consumers are willing and able to purchase at a give price and within a specific time period. Demand, on the other hand, is a broader concept that encompasses the entire relationship between price and quantity demanded
Ezea
how do you save a country economic situation when it's falling apart
what is the difference between economic growth and development
Economic growth as an increase in the production and consumption of goods and services within an economy.but
Economic development as a broader concept that encompasses not only economic growth but also social & human well being.
Shukri
production function means
Jabir
What do you think is more important to focus on when considering inequality ?
any question about economics?
sir...I just want to ask one question... Define the term contract curve? if you are free please help me to find this answer 🙏
Asui
it is a curve that we get after connecting the pareto optimal combinations of two consumers after their mutually beneficial trade offs
Awais
thank you so much 👍 sir
Asui
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities, where neither p
Cornelius
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities,
Cornelius
Suppose a consumer consuming two commodities X and Y has
The following utility function u=X0.4 Y0.6. If the price of the X and Y are 2 and 3 respectively and income Constraint is birr 50.
A,Calculate quantities of x and y which maximize utility.
B,Calculate value of Lagrange multiplier.
C,Calculate quantities of X and Y consumed with a given price.
D,alculate optimum level of output .
the market for lemon has 10 potential consumers, each having an individual demand curve p=101-10Qi, where p is price in dollar's per cup and Qi is the number of cups demanded per week by the i th consumer.Find the market demand curve using algebra. Draw an individual demand curve and the market dema
suppose the production function is given by ( L, K)=L¼K¾.assuming capital is fixed find APL and MPL. consider the following short run production function:Q=6L²-0.4L³ a) find the value of L that maximizes output b)find the value of L that maximizes marginal product
Abdureman
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Source:
OpenStax, Microcontroller and embedded systems laboratory. OpenStax CNX. Feb 11, 2006 Download for free at http://cnx.org/content/col10215/1.29
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