How to use LCD screen from the application board v2

Transcription

1 Made by LEROY Aymeric & LASNE Bruno Customer : RENESAS ELECTRONICS Supervised by WALGER Sébastien How to use LCD screen from the application board v2 LEROY Aymeric & LASNE Bruno Polytech Clermont

2 SOMMARY SOMMARY... 2 INTRODUCTION... 3 I. LCD screen used... 4 II. How to use the LCD Drive Control Unit... 5 II.1. Peripheral features... 5 II.2. Registers settings... 7 II.3. Segments turning on/off III. Fonctions for controlling LCD screen CONCLUSION LEROY Aymeric & LASNE Bruno Polytech Clermont

3 INTRODUCTION In master s degree at Polytech Clermont-Ferrand, I worked on a LCD screen controlled by R8C/L3AB microcontroler from Renesas Electronics. The purpose of this paper is to describe how to control this screen, the registers which need to be set, and explain the codes I made. These codes are joined in the LCD_Project.zip file. LEROY Aymeric & LASNE Bruno Polytech Clermont

4 I. LCD screen used During this project in the electrical department, I use the LCD screen belowed provided by Renesas Electronics. «Application board v2» This screen has 48 segment pins and 4 common pins for being controlled. A specific peripheral LCD Drive Control Unit - included in the R8C/L3AB microcontroler allow us to control this screen. Power supply, refresh frequency, and segments switching are realised thanks to this peripheral. Segment schematics of the LCD screen LEROY Aymeric & LASNE Bruno Polytech Clermont

5 II. How to use the LCD Drive Control Unit II.1. Peripheral features This peripheral is generic, it can be used for different screen with a different number of pins. It can control 56 segment pins maximum and 8 common pins maximum. It can allow the display of the segments with a frequency between 50 and 180Hz, the segments are refreshed between 5,5 ms and 20 ms. General datasheet of the peripheral LEROY Aymeric & LASNE Bruno Polytech Clermont

6 Global schematic of the peripheral For my project, I use 44 segment pins and 4 common pins, so donc Duty = ¼. The source frequency from the microcontroler is 32,768 khz. We should keep in mind that the refresh frequency f(fr) must be up to 50Hz and under 180Hz. So with duty = ¼ with f = 32,768 khz n can have two values (n=32 and n=4) and division ratio can have 7 values (ratio =1, 2, 4, 8, 16, 32, 64), so the product n*division ratio can only have 2 values : 32 et 64. So f(fr) can only have 2 values : 64 et 128Hz. LEROY Aymeric & LASNE Bruno Polytech Clermont

7 «bias control» allow us to set the screen contrast. If you want to set this contrast to this maximum, you must set the register LCR0 in mode «¼ bias», which mean that 4 levels of voltage are going to be supplied by the peripheral. Datasheet for setting contrasts II.2. Registers settings LEROY Aymeric & LASNE Bruno Polytech Clermont

8 Register for setting contrasts and the number of used pins In my case, I have set LCR0 = 0xE3 : - ¼ duty selected because 4 common pins are used - ¼ bias selected for having the best contrast LEROY Aymeric & LASNE Bruno Polytech Clermont

9 Register for setting the power supply of the screen I have set LCR1 = 0xC8 because VL1 = 1.40V. LEROY Aymeric & LASNE Bruno Polytech Clermont

10 Register for setting the blink display mode I have set LCR2 = 0x00 because I don t use this mode. Register for setting the frame frequency to refresh the screen LEROY Aymeric & LASNE Bruno Polytech Clermont

11 I have set LCR3 = 0x44 for setting f(fr) = 128Hz. Register to enable segments used The register LSE0 is shown in example, I have set it to 0xFF. It allow to activate I/O pins which are used as a segment. But keep in mind that you must set the registers LSE1 = 0x00, LSE2 = 0xF0, LSE3 = 0xFF, LSE4 = 0xFF, LSE5 = 0xF0, LSE6 = 0xFF. Some bits are set to 0 because 56 segment pins maximum could be controlled by the LCD Drive Control Unit whereas I use only 40 segment pins. So 16 bits are set to 0. Pins which are not used by the LCD Drive Control Unit could be used as a standard I/O pin. LEROY Aymeric & LASNE Bruno Polytech Clermont

12 Register for activating common pins I have set LSE7 = 0x1F for using 4 common pins. II.3. Segments turning on/off When segment pins are activated, you can display information to the screen thanks to the registers LRA. One register LRA allow to display 8 segments when 8 common pins are enabled, in my case, one register allow to display 4 segments. Register lra to display wanted segments LEROY Aymeric & LASNE Bruno Polytech Clermont

13 For example, for writing the digit 4, you must set segments 21 and 22. Depending on the wiring of the board, this two registers are LRA26l and LRA27l. To display 4, you must refer to the connection table of the segment pins and the common pins to know bits to be set. Finally, LRA26l = 0x03 and LRA27l = 0x06. LEROY Aymeric & LASNE Bruno Polytech Clermont

14 III. Fonctions for controlling LCD screen Here is the main program for using the LCD screen with the «application board v2» : void main(void) { /* LCD Initialisation */ init_lcd(); /* Example of day turning on */ aff_day(sunday); /* Example of logo turning on */ aff_logo(lcd_heat_on); /* Example of volume turning on */ aff_volume(5); } /* Example of digits turning on */ aff_a(1, 3); aff_b(2, 3); aff_c(3, 3); In this program, the LCD screen is initialised thanks to the fonction init_lcd() belowed. The registers LES and LCR are set in this fonction. LEROY Aymeric & LASNE Bruno Polytech Clermont

15 /* LCD initialisation */ void init_lcd(void) { /* Initialise Pointer to Start of Registers */ char *RegPtr = &lra0l; } /* Clear All Segments to 0 */ memset(regptr, 0x00, 56); /* Enable Segment Pins SEG0-7 */ lse0 = 0xFF; /* Enable Segment Pins SEG20-23 */ lse2 = 0xF0; /* Enable Segment Pins SEG24-31 */ lse3 = 0xFF; /* Enable Segment Pins SEG32-39 */ lse4 = 0xFF; /* Enable Segment Pins SEG44-47 */ lse5 = 0xF0; /* Enable Segment Pins SEG48-55 */ lse6 = 0xFF; /* Enable COM Signals 0-3 & CL1-2*/ lse7 = 0x1F; /* Set LCR3 - f(fr) = 128 Hz */ lcr3 = 0x44; /* Set LCR2 - Default Settings, blink mode desabled */ lcr2 = 0x00; //lcr2 = 0x0A; /* Blink enabled */ /* Set LCR1 - set voltage */ lcr1 = 0xC8; /* Set LCR0-4 com used, 1/4 bias */ lcr0 = 0xE3; LEROY Aymeric & LASNE Bruno Polytech Clermont

16 Here are the fonctions to display information on the screen. Three fonctions are reserved for the display of the three digit zones. Then, there is one fonction for battery level, one for sound volume, one for the day of the week, and one for the logos on the screen. void init_lcd(void); void aff_a(char glyph, short digit); void aff_b(char glyph, short digit); void aff_c(char glyph, short digit); void aff_battery(char level); void aff_volume(short level); void aff_day(short day); void aff_logo(short input); These fonctions are tested and caracterized : Init_lcd() has size of 72 bytes and it is executed in 455 cycles aff_day() has size of 558 bytes and it is executed in 24 cycles aff_logo() has size of 586 bytes and it is executed in 11 cycles aff_volume() has size of 259 bytes and it is executed in 17 cycles aff_a() has size of 324 bytes and it is executed in 57 cycles aff_b() has size of 404 bytes and it is executed in 57 cycles aff_c() has size of 649 bytes and it is executed in 120 cycles LEROY Aymeric & LASNE Bruno Polytech Clermont

17 CONCLUSION The LCD screen is ready for being used, it works. You can display information like digit, day of the week, sound volume, battery level, some logos. Then, it is possible to add others fonctions, display of the time, the temperature for example, depending on the wish of the user. LEROY Aymeric & LASNE Bruno Polytech Clermont