ECE 271 Microcomputer Architecture and Applications University of Maine

Transcription

1 ECE Microcomputer Architecture and Applications University of Maine Lab : Liquid Crystal Display (LCD) Driver in C Instructor: Prof. Yifeng Zhu Spring Goals. Understand alternative function of GPIO pins. Understand basic concepts of an LCD driver, particularly Bias and Duty Ratio. Understand concepts of double buffer memory to ensure the coherency of the displayed information. Understand clock configurations of GPIO pins and LCD drivers Pre-lab Assignment:. Read Chapter of Textbook. (Note: Table - and Table - are changed for STML. This lab description gives the updated tables). Complete the pin configuration tables included in this handout In-Lab Assignment:. Complete LCD_PIN_Init( ) and LCD_Configure( ).. Complete LCD_Display_Name( ) to display the first six letters of your last name. You cannot call LCD_DisplayString( ) in LCD_Display_Name( ).. Complete LCD_DisplayString( ) to display a short string. The string has only letters and numbers only, with a length less than.. Something cool. This following gives a few examples. a. LCD cool animations b. LCD scrolling to display a long string c. Set LCD contrast min-->max-->min by pressing user button Introduction PIN configuration: A total of GPIO pins from Port A, B, and C drive the LCD display, as shown below. The duty ratio of this LCD is and therefore there are four common terminals (COM- COM), which are connected to four GPIO pins. The other GPIO pins are mapped to pixel bits stored in the internal LCD RAM. The mapping between GPIO pins and LCD RAM are given in the textbook. Each pin should be configured as Alternative Function (LCD Driver). Figure. PIN connection to six -segment digits and bars.

2 ECE Microcomputer Architecture and Applications University of Maine Modification to the program flowchart (Figure - in Textbook): For the STML discovery kit, the MUS_SEG bit in the LCD_CR must be cleared. SEG[:] are not multiplexed with SEG[:]. LCD ( segments, commons, multiplexed / duty, / bias) on DIP connector VLCD = PC COM = PA (LCD_COM) COM = PA (LCD_COM) COM = PA (LCD_COM) COM = PB (LCD_COM) SEG =PA (LCD_SEG) SEG = PD (LCD_SEG) SEG = PB (CD_SEG) SEG = PD (LCD_SEG) SEG = PC (LCD_SEG) SEG = PD (LCD_SEG) SEG = PC (LCD_SEG) SEG = PB (LCD_SEG) SEG = PB (LCD_SEG) SEG = PD (LCD_SEG) SEG = PC (LCD_SEG) SEG = PB (LCD_SEG) SEG = PB (LCD_SEG) SEG = PC (LCD_SEG) SEG = PD (LCD_SEG) SEG = PB (LCD_SEG) SEG = PB (LCD_SEG) SEG = PA (LCD_SEG) SEG = PD (LCD_SEG) SEG = PC (LCD_SEG) SEG = PD (LCD_SEG) SEG = PB (LCD_SEG) SEG = PD (LCD_SEG) SEG = PA (LCD_SEG) LCD STML Pin LCD Pin COM COM COM COM LCD Pin PA (LCD_SEG) N P D E SEG PC (LCD_SEG) DP COLON C M SEG PB (LCD_SEG) N P D E SEG PB (LCD_SEG) DP COLON C M SEG PB (LCD_SEG) N P D E SEG PD (LCD_SEG) DP COLON C M SEG PD (LCD_SEG) N P D E SEG PD (LCD_SEG) DP COLON C M SEG PD (LCD_SEG) N P D E SEG PC (LCD_SEG) BAR BAR C M SEG PA (LCD_SEG) N P D E SEG PB (LCD_SEG) BAR BAR C M SEG PB (LCD_COM) COM PA (LCD_COM) COM PA (LCD_COM) COM PA (LCD_COM) COM PB (LCD_SEG) J K A B SEG PC (LCD_SEG) H Q F G SEG PC (LCD_SEG) J K A B SEG PD (LCD_SEG) H Q F G SEG PD (LCD_SEG) J K A B SEG PD (LCD_SEG) H Q F G SEG PD (LCD_SEG) J K A B SEG PB (LCD_SEG) H Q F G SEG PB (LCD_SEG) J K A B SEG PB (LCD_SEG) H Q F G SEG PC (LCD_SEG) J K A B SEG PA (LCD_SEG) H Q F G SEG

3 ECE Microcomputer Architecture and Applications University of Maine Lab :Pre-Lab Assignment Student Name: TA: Time & Date:. Configure Port A: Pin,,,,, as Alternative Function Mode GPIO Mode: Digital Input (, reset), Digital Output (), Alternative Function (), Analog () MODER MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] GPIOA Mode Value = x (in HEX) GPIOA Mode Value = x (in HEX) Configure Port A: Pin,,,,, and as Alternative Function (xb) AFR[] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFR[] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] GPIOA Alternative Function [] = x (in HEX) GPIOA Alternative Function [] = x (in HEX) GPIOA Alternative Function [] = x (in HEX) GPIOA Alternative Function [] = x (in HEX)

4 ECE Microcomputer Architecture and Applications University of Maine. Configure Port B: Pin,,,,,,,, and as Alternative Function Mode GPIO Mode: Digital Input (, reset), Digital Output (), Alternative Function (), Analog () MODER MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] GPIOB Mode Value = x (in HEX) GPIOB Mode Value = x (in HEX) Configure Port B: Pin,,,,,,,, and as Alternative Function (xb) AFR[] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFR[] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] GPIOB Alternative Function [] = x (in HEX) GPIOB Alternative Function [] = x (in HEX) GPIOB Alternative Function [] = x (in HEX) GPIOB Alternative Function [] = x (in HEX)

5 ECE Microcomputer Architecture and Applications University of Maine. Configure Port C: Pin,,,,, and as Alternative Function Mode GPIO Mode: Digital Input (, reset), Digital Output (), Alternative Function (), Analog () MODER MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] GPIOC Mode Value = x (in HEX) GPIOC Mode Value = x (in HEX) Configure Port C: Pin,,,,, and as Alternative Function (xb) AFR[] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFR[] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] GPIOC Alternative Function [] = x (in HEX) GPIOC Alternative Function [] = x (in HEX) GPIOC Alternative Function [] = x (in HEX) GPIOC Alternative Function [] = x (in HEX)

6 ECE Microcomputer Architecture and Applications University of Maine. Configure Port D: Pin,,,,,,, and as Alternative Function Mode GPIO Mode: Digital Input (, reset), Digital Output (), Alternative Function (), Analog () MODER MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] MODER[:] GPIOD Mode Value = x (in HEX) GPIOD Mode Value = x (in HEX) Configure Port D: Pin,,,,,,, and as Alternative Function (xb) AFR[] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFRL[:] AFR[] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] AFRH[:] GPIOD Alternative Function [] = x (in HEX) GPIOD Alternative Function [] = x (in HEX) GPIOD Alternative Function [] = x (in HEX) GPIOD Alternative Function [] = x (in HEX)

7 ECE Microcomputer Architecture and Applications University of Maine Write down your last name, and complete the following table. Your Last Name: (First Six Characters) LCD_RAM[] E G M B G M B M B E E G M B B M E G E G LCD_RAM[] E G M B LCD_RAM[] D F C A F C A C A D D F C A A C D F D F LCD_RAM[] D F C A LCD_RAM[] P Q Col K Q K Bar Col K P P Q Col K K Bar P Q P Q LCD_RAM[] P Q Col K LCD_RAM[] N H DP J H J Bar DP J N N H DP J J Bar N H N H LCD_RAM[] N H DP J LCD_RAM is an array of -bit unsigned integers. LCD_RAM[] = x (in Hex) LCD_RAM[] = x (in Hex) LCD_RAM[] = x (in Hex) LCD_RAM[] = x (in Hex) LCD_RAM[] = x (in Hex) LCD_RAM[] = x (in Hex) LCD_RAM[] = x (in Hex) LCD_RAM[] = x (in Hex)

8 ECE Microcomputer Architecture and Applications University of Maine Complete the following configuration table for LCD registers.. Refer to Figure - of Textbook and STML Reference Manual to complete the following table.. For STML discovery kit, the mux segment of the LCD_CR must be disabled, i.e. the MUX_SEG bit in the LCD_CR register must be cleared. SEG[:] are not multiplexed with SEG[:]. The flow chart (Figure - in textbook) is for STML discovery kit and it sets MUX_sets bit in the LCD_CR register to make output pins SEG[:] have function SEG[:]. Offset x LCD_CR BUFEN. MUX_SEG. BIAS[:] DUTY [:] VSEL LCDEN value x LCD_FCR PS[:] DIV[:] BLINK[:] BLINKF[:] CC [:] DEAD [:] PON [:] UDDIE SOFIE HD value x LCD_SR value FCRSF RDY UDD UDR SOF ENS xc LCD_CLR UDDC SOFC value

9 ECE Microcomputer Architecture and Applications University of Maine Lab : In-Lab Assignment The basic requirement of this lab is to display your last name on the LCD. Refer to Textbook for the flow charts. Notes:. The code uses the stmlxx.h head file provided in the STM library. It includes many useful macro definitions and data structures. Using them makes your code easier to understand and debug.. The program code to initialize the LCD clock is provided to you. The function is LCD_Clock_Init(); a. The LCD clock is the same clock as the Real-time clock (RTC). RTC clock domain is protected by default. To configure the LCD clock source, the RTC domain needs to be unlocked first by writing xca and x to the RTC->WPR register.. You are required to implement four functions: a. LCD_PIN_Init() that enables GPIO clocks and configures GPIO pins as the alternative function (LCD) b. LCD_Configure() that performs the LCD configuration in the flow chart c. LCD_Display_Name() that display the first six letters of your last name d. LCD_Display_String() that sets up the LCD_RAM and displays the input string on LCD. e. LCD_Clear() that clear the LCD screen.. Examples of something cool a. LCD cool animations b. LCD scrolling to display a long string c. Set LCD contrast min max min by pressing user button d. Something really cool Lab Demo Questions:. In the LCD_WriteChar( ) function, why do we use the following while statement while ((LCD->SR & LCD_SR_UDD) == );. What clock is used to drive the LCD? How can you find out? (Hint: check RCC register value in debug environment). Explain to TA why double-buffering can ensure the coherency of the displayed information

10 ECE Microcomputer Architecture and Applications University of Maine Lab : Post-Lab Assignment Answer the following questions in the file Readme.md and submit it with your lab code to the gitlab server.. Suppose the duty ratio of a LCD display is ¼ and it has a total of display segments (pixels). How many pins are required to drive this LCD?. Can a GPIO pin perform all alternative functions simultaneously?. Is the LCD driver (programmed in this lab) built in within the processor chip? What is the function of the COM driver and SEG driver?. How many pixels can the STML processor LCD driver drive? How large is the LCD_RAM in terms of bits? (Read STML Reference Manual). How many pixels does the LCD installed on the STML discovery kit have? Explain why many LCD_RAM bits are not used for this LCD?