Tutorial 1 Introduction to MSP430 microcontrollers

MSP430G2553 MCU datasheet


1. Introduction to the MCU

From the first paragraph in the datasheet, we can tell that this MCU is designed for low power applications, it is a 16-bit system, it has a 32 kHz crystal clock source, and the power supply is 1.8 V - 3.6 V.



Populate R5/R7 and remove R3/R9 to enable the 32kHz low power crystal. (Refer to the schematic)



On the right-hand side, we know that this MCU has UART, SPI, I2C, and a 10-bit ADC available inside the chip.



The device pinout (MSP430G2ET is the evaluation board, MSP430G2553 is the name of the MCU chip).
Refer to Page 6-8 on the datasheet for the functions of the pins.



It's always important to know these critical information before you start using the chip so you know what you will expect from this MCU.


2. Installation of the Energia IDE.

Visit Energia's website to download the newest Energia IDE.



Extract the downloaded package on your C drive and double click energia.exe.



Install the driver to your computer.
Go to this link: https://energia.nu/guide/install/windows/

Select 'MSP-EXP430G2 and MSP-EXP430FR5739 Launch Pad'



If you have a 64-bit Windows PC then do double click the following item.



Open Energia.exe in the folder and select the correct board:



Go to Tools - Board Manager, install the newest Energia MSP430 boards. (Important)



Find a blink example to test if your PC and the board communicate with each other.



3. Serial communication

The direction of the jumpers in the following figure doesn't affect the program to be uploaded from the PC to the board. You can even unplug them while the code is being uploaded to it. However, if you need to debug your code (watch the serial data being sent back to the PC in a serial monitor), you must rotate the jumpers and select the UART1 COM port.
The rule of thumb is just keep the jumpers connected as what is in the following figure for Programming and Debugging. Always use the UART1 port for any purposes.





Try this simple code and open the serial monitor to verify the functionality of the board and serial communication.

void setup() {
  Serial.begin(9600);
}
void loop() {
  Serial.println("test");
  delay(1000); 
}

You should see this:



Let's read some data from the ADCs and display them in the serial monitor.
On the datasheet, you can see that the MCU has 8 ADC ports.
The 2553 versions all have 8 ADC channels:



Can you locate the 8 ADC ports on the boad by reading Page 6 - 7 on the datasheet?

From the schematic, I see this:



But where are P1.0 and P1.6? Ok, let's take a look at the MCU's pinout. Not too bad, only 20 pins - an entry-level MCU.



Now, let's build a voltage divider using a potentiometer (in you box) and a 10k resistor. The output goes to A0 of the MCU (one of the ADC inputs), let the MCU digitize the analog voltage input at A0 and directly use the digitized value as the time delay to blink the LED connected to Pin 14.
Because the Green LED (D1) is directly shorted to A0, when the voltage input varies, the brightness of D1 will vary as well. Wait.... Is there a protection resistor for the Green LED (D1)?

Yes there is! The 390 ohm resistor is just about right. Let's code it up! It should be a pretty simple and interesting experiment.



Hardware connection:



Connect from the back of the board becaue the wires available are male-to-male.



Code:

// Example 2, analog input
int sensorPin = A0;    // select the input pin for the potentiometer
int sensorValue = 0;  // variable to store the value coming from the sensor

void setup() {
  // declare the 14 pin as an OUTPUT:
  pinMode(14, OUTPUT); 
  Serial.begin(9600);
}

void loop() {
  // read the value from the sensor:
  sensorValue = analogRead(sensorPin);   
  // turn the ledPin on
  digitalWrite(14, HIGH); 
  // stop the program for <sensorValue> milliseconds:
  delay(sensorValue);         
  // turn the ledPin off:       
  digitalWrite(14, LOW);  
  // stop the program for for <sensorValue> milliseconds:
  delay(sensorValue);  
  Serial.println(sensorValue);              
}

Video Demonstration:



Open the serial monitor to check the maximum and the minimum possible values. Why the minimum value is higher than VDD/2?

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Tasks:

Repeat all the experiments in this tutorial. (20 points)