Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
learn:courses:unit-3-lab3b:start [2017/02/14 23:39] – Marthalearn:courses:unit-3-lab3b:start [2021/10/13 22:14] (current) – Arthur Brown
Line 1: Line 1:
-====== Lab 3b: LCD Parallel Interface - PMP IO Control ======+====== Lab 3b: LCD Parallel Interface - PMP I/O Control ====== 
 +[[{}/learn/courses/unit-3/start|Back to Unit 3]] 
 +[[{}/learn/courses/unit-3-lab3a/start|Back to Lab 3a]]
 == Download This Document == == Download This Document ==
-  * +{{ :learn:courses:unit-3-lab3b:lab_3b.pdf |Lab 3b PDF}}
  
 ===== 1. Objectives ===== ===== 1. Objectives =====
-  - Develop an application of foreground-background task scheduling. +  - Identify the PIC32 processor pins used for the LCD interface. 
-  - Use change notification interrupts to detect push button presses and releases. +  - Implement LCD control using the PIC32 Parallel Master Port (PMP).  
-  - Eliminate multiple button operations using a timer interrupt to implement a non-blocking delay. +  - Understand handshaking requirements for interfacing two systems operating at differing clock speeds.
-  - Implement the push-on / push off operation using a software-based finite state machine. +
  
 ---- ----
Line 23: Line 23:
 ===== 3. Equipment List ===== ===== 3. Equipment List =====
 ==== 3.1. Hardware ==== ==== 3.1. Hardware ====
-  - Basys MX3 trainer board. +  - [[https://digilent.com/shop/basys-mx3-pic32mx-trainer-board-for-embedded-systems-courses/|Basys MX3 trainer board]] 
-  - PC or Linux Workstation computer. +  - [[https://digilent.com/shop/usb-a-to-micro-b-cable/|Micro USB cable]] 
-  - [[http://store.digilentinc.com/usb-a-to-micro-b-cable/|Micro USB cable]]. +  - Workstation computer running Windows 10 or higher, MAC OS, or Linux 
-  - [[http://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/|Analog Discovery 2]]. + 
 +In addition, we suggest the following instruments: 
 + 
 +  - [[http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,842,1018&Prod=ANALOG-DISCOVERY|Digilent Analog Discovery 2]]
  
  
 ==== 3.2. Software: ==== ==== 3.2. Software: ====
-  - [[http://www.microchip.com/mplab/mplab-x-ide|Microchip MPLAB X® v3.35 or higher]]. +The following programs must be installed on your development workstation:
-  - [[http://www.microchip.com/SWLibraryWeb/product.aspx?product=PIC32%20Peripheral%20Library|PLIB Peripheral Library]]. +
-  - [[http://store.digilentinc.com/waveforms-2015-download-only/|WaveForms 2015]].+
  
 +  - [[http://www.microchip.com/mplab/mplab-x-ide|Microchip MPLAB X® v3.35 or higher]]
 +  - [[http://www.microchip.com/SWLibraryWeb/product.aspx?product=PIC32%20Peripheral%20Library|PLIB Peripheral Library]]
 +  - [[http://www.microchip.com/xcdemo/xcpluspromo.aspx|XC32 Cross Compiler]]
 +  - [[https://digilent.com/shop/software/digilent-waveforms/|WaveForms]]
  
 ---- ----
  
 ===== 4. Project Takeaways ===== ===== 4. Project Takeaways =====
-  - How to implement a bi-directional parallel IO interface.+  - How to implement a bi-directional parallel I/O interface.
   - How to use delays to control signal timing.   - How to use delays to control signal timing.
   - How to manage ASCII text strings.   - How to manage ASCII text strings.
- 
  
 ---- ----
Line 51: Line 55:
  
 ===== 6. Problem Statement ===== ===== 6. Problem Statement =====
-Develop and test a collection of functions that allow text to be placed at any position on a parallel I/O character LCD following the DFD and CFD models presented in Unit 3. The LCD_puts function is required to process the [[http://www.asciitable.com/|ASCII control characters]], which are described in Table 8.1.+Develop and test a collection of functions that allow text to be placed at any position on a parallel I/O character LCD following the DFD and CFD models presented in Unit 3. The //LCD_puts// function is required to process the [[http://www.asciitable.com/|ASCII control characters]], which are described in Table 8.1.
  
  
Line 57: Line 61:
  
 ===== 7. LCD Background Information ===== ===== 7. LCD Background Information =====
-Character [[https://en.wikipedia.org/wiki/Liquid-crystal_display|Liquid Crystal Displays]] (LCD) are low cost electronic devices that are capable of generating visual displays consisting of alphanumeric characters and graphical symbols commonly used for [[https://en.wikipedia.org/wiki/Embedded_system|embedded system]] [[https://en.wikipedia.org/wiki/User_interface|human machine interfaces]] (HMI). Many suppliers of LCD devices are based on the [[https://en.wikipedia.org/wiki/Hitachi_HD44780_LCD_controller|Hitachi HD44780]] LCD controller, and hence have a common hardware and software interface. Some LCD devices have serial interfaces that use UART, I2C, and SPI communications. These protocols are covered in Unit 4. Other LCD devices use interfaces consisting of four or eight data lines and three control lines. Although the LCDs that use a serial interface require fewer processor I/O pins, the display controller IC is still based on the Hitachi HD44780, which uses 8 or 11 I/O pins. Hence, the serial LCD devices have an on-board microprocessor that translates the serial communications instructions to parallel I/O. +Character [[https://en.wikipedia.org/wiki/Liquid-crystal_display|Liquid Crystal Displays]] (LCD) are low-cost electronic devices that are capable of generating visual displays consisting of alphanumeric characters and graphical symbols commonly used for [[https://en.wikipedia.org/wiki/Embedded_system|embedded system human machine interfaces]] (HMI). Many suppliers of LCD devices are based on the [[https://en.wikipedia.org/wiki/Hitachi_HD44780_LCD_controller|Hitachi HD44780]] LCD controller, and hence have a common hardware and software interface. Some LCD devices have serial interfaces that use UART, I2C, and SPI communications((PmodCLS: Character LCD with Serial Interface, [[https://digilent.com/shop/pmod-cls-character-lcd-with-serial-interface/]])). These protocols are covered in Unit 4. Other LCD devices use interfaces consisting of four or eight data lines and three control lines((PmodCLP Character LCD with Parallel Interface, [[https://digilent.com/reference/pmod/pmodclp/start]])). Although the LCDs that use a serial interface require fewer processor I/O pins, the display controller IC is still based on the Hitachi HD44780, which uses 8 or 11 I/O pins. Hence, the serial LCD devices have an on-board microprocessor that translates the serial communications instructions to parallel I/O. 
  
-The handshaking required to successfully communicate with the LCD on the Basys MX3 is representative of many common parallel interfaces. +The handshaking required to successfully communicate with the LCD on the Basys MX3 is representative of many common parallel interfaces.
  
  
Line 67: Line 71:
 ===== 8. Lab 3a ===== ===== 8. Lab 3a =====
 ==== 8.1. Requirements ==== ==== 8.1. Requirements ====
-  - All LCD interface pin control will use //LATx//, //LATxSET//, or //LATxCLR// instructions for outputs and //PORTxBITS// for inputs.+  - All LCD interface pin control will use PMP interface as described in the Unit 3 text.
   - Write a library of functions to provide general capability to display strings of text, characters, and numbers at specified positions on the LCD display.    - Write a library of functions to provide general capability to display strings of text, characters, and numbers at specified positions on the LCD display. 
   - All LCD control sequences must meet the strict timing requirements for the following operations:   - All LCD control sequences must meet the strict timing requirements for the following operations:
-    - Initialize the LCD using the recommended sequence of instructions shown in the control flow diagram FIg. B.2. to write specific codes to the LCD at specified intervals.+    - Initialize the LCD using the recommended sequence of instructions to write specific codes to the LCD at specified intervals, shown in the control flow diagram of Fig. B.2.
     - Position the cursor in the display space (Line 1 or Line 2) where the next character is to be displayed.     - Position the cursor in the display space (Line 1 or Line 2) where the next character is to be displayed.
-    - Write function(s) that write ASCII control and display data to the Display Data Ram (DDRAM). one or more? +    - Write function(s) that write ASCII control and display data to the Display Data Ram (DDRAM). 
-    - Translate the ASCII control characters into one or more C instructions for the LCD, as detailed in Table 8.1.+    - Translate the ASCII control characters into one or more C instructions for the LCD as detailed in Table 8.1.
     - Write functions that write ASCII character data to the Display Data Ram (DDRAM).     - Write functions that write ASCII character data to the Display Data Ram (DDRAM).
       - Write a function that will write a single ASCII encoded character to the display.       - Write a function that will write a single ASCII encoded character to the display.
       - Write a function that will write a string (array) of ASCII encoded characters to the display.       - Write a function that will write a string (array) of ASCII encoded characters to the display.
-  - Using the following program, develop a test project that will verify that the function //LCD_puts(byte *str);// correctly displays an array of ASCII text and control characters.<code>+  - Using the following program, develop a test project that will verify that the function LCD_puts(byte *str); correctly displays an array of ASCII text and control characters.<code>
 char test_str[] = “ User generated test string”; char test_str[] = “ User generated test string”;
 int main(void) int main(void)
 { {
- hardware_setup(void); // Initialize the LCD IO pins+ hardware_setup(void); // Initialize the LCD IO pins
  LCD_init(); // Initialize LCD  LCD_init(); // Initialize LCD
  while(1)  while(1)
  {  {
  LCD_puts(test_str); // Display the text string  LCD_puts(test_str); // Display the text string
- DelayMs(1000); // Delay 1 second+ DelayMs(1000); // Delay 1 second
  LCDWrite(0x01); // Clear LCD   LCDWrite(0x01); // Clear LCD
  }  }
 } }
 </code> </code>
-  - Write an application program for the BASYS MX3 processor board that achieves the following:+  - Write an application program for the Basys MX3 processor board that achieves the following:
     - Initializes a loop counter to a value of zero.     - Initializes a loop counter to a value of zero.
     - Displays your name on the first line.     - Displays your name on the first line.
-    - Repositions the cursor to the beginning of the second line and displays the text “LAB 3.”+    - Repositions the cursor to the beginning of the second line and displays the text “Lab 3b.”
     - Repositions the cursor to the eighth character position of the second line.     - Repositions the cursor to the eighth character position of the second line.
     - Displays the value of the loop counter.     - Displays the value of the loop counter.
     - Increments the loop counter.     - Increments the loop counter.
     - Delays one second before repeating steps d through g.     - Delays one second before repeating steps d through g.
 +
  
 **Table 8.1.  LCD controls.** **Table 8.1.  LCD controls.**
Line 109: Line 114:
 ==== 8.2. Design Phase ==== ==== 8.2. Design Phase ====
   - Generate a project in MPLAB X.   - Generate a project in MPLAB X.
-  - Copy the config.bits file to the project directory. +  - Copy the config.bits file to the project directory.
   - Open three new C files: main.c, lcd.c, and swdelay.c.   - Open three new C files: main.c, lcd.c, and swdelay.c.
   - Open two new header files: lcd.h and swdelay.h.   - Open two new header files: lcd.h and swdelay.h.
   - Generate the contents of the main.c file for the initialization code and the infinite loop.   - Generate the contents of the main.c file for the initialization code and the infinite loop.
-  - In swdelay.c, generate a function prototype for the //msDelay(unsigned int dly);// function. +  - In swdelay.c, generate a function prototype for the msDelay(unsigned int dly); function. 
-    - Copy the software delay function from Unit 2, Listing 3 to swdelay.c.+    - Copy the software delay function from Unit 2, Listing 7.3 to swdelay.c.
   - In lcd.h, generate function prototypes for the five LCD functions shown in Fig. B.1.   - In lcd.h, generate function prototypes for the five LCD functions shown in Fig. B.1.
-  - Generate the code for the five LCD functions in lcd.c. +  - Generate the code for the five LCD functions in lcd.c. 
    
 ==== 8.3. Construction Phase ==== ==== 8.3. Construction Phase ====
Line 131: Line 137:
   - List the processor hardware resources that you will be using in this design.   - List the processor hardware resources that you will be using in this design.
   - Generate a data flow diagram that identifies tasks (functions) and the information that needs to be passed between these tasks.   - Generate a data flow diagram that identifies tasks (functions) and the information that needs to be passed between these tasks.
-  - Using the DFD and the multiple CFDs shown in Appendix B, develop and test the functions that will initialize the LCD and display single characters and a string of characters. You should use the? software delay function used in Lab 1b.+  - Using the DFD and the multiple CFDs shown in Appendix B, develop and test the functions that will initialize the LCD and display single characters and a string of characters. You should use the software delay function used in Lab 1b. 
  
 ==== 8.4. Testing ==== ==== 8.4. Testing ====
   - Demonstrate that the test program developed for requirement 4 executes correctly using the test string “\0141234\0115678\0119ABC\r”.   - Demonstrate that the test program developed for requirement 4 executes correctly using the test string “\0141234\0115678\0119ABC\r”.
   - Demonstrate that the test program developed for requirement 5 executes correctly.   - Demonstrate that the test program developed for requirement 5 executes correctly.
 +
  
 ---- ----
  
 ===== 9. Questions ===== ===== 9. Questions =====
 +  - What are the advantages of using the PMP interface over the bit-banging interface?
 +  - What are the advantages of using the bit-banging interface over the PMP interface?
   - How would the LCD display be affected if the application described above is combined with an application that uses interrupts?    - How would the LCD display be affected if the application described above is combined with an application that uses interrupts? 
-  - How can the blocking semaphore represented by the Busy Flag be eliminated? 
   - What is the maximum rate at which characters can be written to the LCD?   - What is the maximum rate at which characters can be written to the LCD?
 +
  
 ---- ----
Line 156: Line 166:
  
 ===== Appendix A: Basys MX3 Schematic Drawings ===== ===== Appendix A: Basys MX3 Schematic Drawings =====
-{{ :learn:courses:unit-3-lab3a:lab3a-figure-a-1.png?nolink |Figure A.1. LCD connection schematic diagram for Labs 3a and 3b.}}+{{ :learn:courses:unit-3-lab3b:lab_3b_3_fig_a_1.jpg?nolink&550 |Figure A.1. LCD connection schematic diagram for Labs 3a and 3b.}}
 //Figure A.1. LCD connection schematic diagram for Labs 3a and 3b.// //Figure A.1. LCD connection schematic diagram for Labs 3a and 3b.//
- 
  
 ---- ----
Line 173: Line 182:
  
 {{ :learn:courses:unit-3-lab3a:lab3a-figure-b-4.png?nolink |Figure B.3. Control flow diagram for LCD Write operation using bit-banging.}} {{ :learn:courses:unit-3-lab3a:lab3a-figure-b-4.png?nolink |Figure B.3. Control flow diagram for LCD Write operation using bit-banging.}}
-//Figure B.3. Control flow diagram for LCD Write operation using bit-banging.//+//Figure B.4. Control flow diagram for LCD Write operation using bit-banging.//
  
 {{ :learn:courses:unit-3-lab3a:lab3a-figure-b-5.png?nolink |Figure B.5. LCD display character control flow diagram.}} {{ :learn:courses:unit-3-lab3a:lab3a-figure-b-5.png?nolink |Figure B.5. LCD display character control flow diagram.}}
 //Figure B.5. LCD display character control flow diagram.// //Figure B.5. LCD display character control flow diagram.//
 +
 +----
 +
 +[[{}/learn/courses/unit-3/start|Back to Unit 3]]
 +[[{}/learn/courses/unit-3-lab3a/start|Back to Lab 3a]]
 +[[{}/learn/courses/unit-4-1/start|Go to Unit 4 Part 1]]
 +