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Connecting the small CFAF128128B-0145T TFT to an Arduino Uno or SparkFun RedBoard

CF Tech

Administrator
A customer asked for some help connecting the CFAF128128B-0145T 1.45" 12x128 full color TFT LCD. They wanted to have an example that only used software, so they could port it easily to their proprietary system.

I decided to use a SparkFun RedBoard that I had on my desk. I have also tested the code on a true-blue Arduino Uno R3, and it worked identically -- as you would expect.

To start, we need a plan -- in the form of a schematic (the full resolution PDF):


I used a small adapter board to break out the CFAF128128B-0145T 0.5mm FPC tail to 0.1" center pins, then used some WRJMPY40 to connect it up:

Update: kprice has uploaded a nice little ZIF breakout board at OSH Park that could be used here:
https://oshpark.com/shared_projects/PeXUHK4z



On back of the adapter board we added a 156 ohm dropping resistor for the white LED backlight, and jumped the spi mode line to high, selecting the 4-wire mode:


Connecting to the RedBoard/Arduino for power is straight-forward:


The LCD runs at 3.3v, but the RedBoard/Arduino runs at 5v so there is a problem with the voltage levels. One option is to use a level translator, but in this simple write-only example we can use current limiting resistors to protect the input on the LCD:


For the code, we made about the simplest sketch we could. This code stresses simplicity over speed. It can be used with the Arduino/RedBoard hardware SPI, or bit-banged software SPI:
CFAF128128B-0145T_SPI_Demo_Code.ino

Code:
//===========================================================================
//
//  Code written for Arduino Uno R3
//
//  CRYSTALFONTZ CFAF128128B-0145T 128X128 SPI COLOR 1.45" TFT
//
//  Super-simple software bit-bang example code.
//
//  ref: https://www.crystalfontz.com/product/cfaf128128b0145t
//
//  2015 - 12 - 31 Brent A. Crosby
//===========================================================================
//This is free and unencumbered software released into the public domain.
//
//Anyone is free to copy, modify, publish, use, compile, sell, or
//distribute this software, either in source code form or as a compiled
//binary, for any purpose, commercial or non-commercial, and by any
//means.
//
//In jurisdictions that recognize copyright laws, the author or authors
//of this software dedicate any and all copyright interest in the
//software to the public domain. We make this dedication for the benefit
//of the public at large and to the detriment of our heirs and
//successors. We intend this dedication to be an overt act of
//relinquishment in perpetuity of all present and future rights to this
//software under copyright law.
//
//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
//EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
//MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
//IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
//OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
//ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
//OTHER DEALINGS IN THE SOFTWARE.
//
//For more information, please refer to <http://unlicense.org/>
//============================================================================
//
// Display is Crystalfontz CFAF128128B-0145T
//   https://www.crystalfontz.com/product/cfaf128128b0145t
//
// The controller is a Sitronix ST7735S
//   http://www.crystalfontz.com/controllers/Sitronix/ST7735S/
//
//============================================================================
#define HARDWARE_SPI 0
#include <avr/io.h>
#if(HARDWARE_SPI)
// C:\Program Files (x86)\Arduino\hardware\arduino\avr\libraries\SPI\SPI.cpp
// C:\Program Files (x86)\Arduino\hardware\arduino\avr\libraries\SPI\SPI.h
#include <SPI.h>
#endif
#include <util/delay.h>
#include <avr/pgmspace.h>
// This is supposed to be set somewhere in the AVR Studio, but I can't find
// the place :( In any case, our dev board, an Arduino UNO R3 runs at 16MHz,
// and this define makes the delays come out correctly.
# define F_CPU 16000000UL
//============================================================================
//
// LCD SPI & control lines
//   ARD   | Port | LCD
// --------+------+-------------------------
//  #8/D8  |  PB0 | LCD_RS
//  #9/D9  |  PB1 | LCD_RESET
// #10/D10 |  PB2 | LCD_CS_NOT (or SPI SS)
// #11/D11 |  PB3 | LCD_MOSI (hardware SPI)
// #12/D12 |  PB4 | not used (would be MISO)
// #13/D13 |  PB5 | LCD_SCK (hardware SPI)

#define CLR_RS    (PORTB &= ~(0x01))
#define SET_RS    (PORTB |=  (0x01))
#define CLR_RESET (PORTB &= ~(0x02))
#define SET_RESET (PORTB |=  (0x02))
#define CLR_CS    (PORTB &= ~(0x04))
#define SET_CS    (PORTB |=  (0x04))
#define CLR_MOSI  (PORTB &= ~(0x08))
#define SET_MOSI  (PORTB |=  (0x08))
#define CLR_SCK   (PORTB &= ~(0x20))
#define SET_SCK   (PORTB |=  (0x20))
//============================================================================
void SPI_Bit_Bang_Transfer(uint8_t data)
  {
  //Push each of the 8 data bits out.
  for(uint8_t mask=0x80;mask;mask>>=1)
    {
    //Set the MOSI pin high or low depending on if our mask
    //corresponds to a 1 or 0 in the data.
    if(mask&data)
      {
      SET_MOSI;
      }
    else
      {
      CLR_MOSI;
      }
    //Clock it in.
    SET_SCK;
    CLR_SCK;
    }
  }
//============================================================================
void SPI_sendCommand(uint8_t command)
  {
  // Select the LCD's command register
  CLR_RS;
  // Select the LCD controller
  CLR_CS;
  //Send the command via SPI:
#if(HARDWARE_SPI)
  SPI.transfer(command);
#else
  SPI_Bit_Bang_Transfer(command);
#endif
  // Deselect the LCD controller
  CLR_CS;
  }
//----------------------------------------------------------------------------
void SPI_sendData(uint8_t data)
  {
  // Select the LCD's data register
  SET_RS;
  // Select the LCD controller
  CLR_CS;
  //Send the command via SPI:
#if(HARDWARE_SPI)
  SPI.transfer(data);
#else
  SPI_Bit_Bang_Transfer(data);
#endif
  // Deselect the LCD controller
  CLR_CS;
  }
//----------------------------------------------------------------------------
// Defines for the ST7735 registers.
// ref: https://www.crystalfontz.com/products/document/3277/ST7735_V2.1_20100505.pdf
#define ST7735_SLPOUT   (0x11)
#define ST7735_DISPON   (0x29)
#define ST7735_CASET    (0x2A)
#define ST7735_RASET    (0x2B)
#define ST7735_RAMWR    (0x2C)
#define ST7735_RAMRD    (0x2E)
#define ST7735_MADCTL   (0x36)
#define ST7735_COLMOD   (0x3A)
#define ST7735_FRMCTR1  (0xB1)
#define ST7735_FRMCTR2  (0xB2)
#define ST7735_FRMCTR3  (0xB3)
#define ST7735_INVCTR   (0xB4)
#define ST7735_PWCTR1   (0xC0)
#define ST7735_PWCTR2   (0xC1)
#define ST7735_PWCTR3   (0xC2)
#define ST7735_PWCTR4   (0xC3)
#define ST7735_PWCTR5   (0xC4)
#define ST7735_VMCTR1   (0xC5)
#define ST7735_GAMCTRP1 (0xE0)
#define ST7735_GAMCTRN1 (0xE1)
//----------------------------------------------------------------------------
void Initialize_LCD(void)
  {
  //Reset the LCD controller
  CLR_RESET;
  delay(1);//10µS min
  SET_RESET;
  delay(150);//120mS max

  //SLPOUT (11h): Sleep Out ("Sleep Out"  is chingrish for "wake")
  //The DC/DC converter is enabled, Internal display oscillator
  //is started, and panel scanning is started.
  SPI_sendCommand(ST7735_SLPOUT);
  delay(120);

  //FRMCTR1 (B1h): Frame Rate Control (In normal mode/ Full colors)
  //Set the frame frequency of the full colors normal mode.
  // * Frame rate=fosc/((RTNA + 20) x (LINE + FPA + BPA))
  // * 1 < FPA(front porch) + BPA(back porch) ; Back porch ?0
  //Note: fosc = 333kHz
  SPI_sendCommand(ST7735_FRMCTR1);//In normal mode(Full colors)
  SPI_sendData(0x02);//RTNB: set 1-line period
  SPI_sendData(0x35);//FPB:  front porch
  SPI_sendData(0x36);//BPB:  back porch

  //FRMCTR2 (B2h): Frame Rate Control (In Idle mode/ 8-colors)
  //Set the frame frequency of the Idle mode.
  // * Frame rate=fosc/((RTNB + 20) x (LINE + FPB + BPB))
  // * 1 < FPB(front porch) + BPB(back porch) ; Back porch ?0
  //Note: fosc = 333kHz
  SPI_sendCommand(ST7735_FRMCTR2);//In Idle mode (8-colors)
  SPI_sendData(0x02);//RTNB: set 1-line period
  SPI_sendData(0x35);//FPB:  front porch
  SPI_sendData(0x36);//BPB:  back porch

  //FRMCTR3 (B3h): Frame Rate Control (In Partial mode/ full colors)
  //Set the frame frequency of the Partial mode/ full colors.
  // * 1st parameter to 3rd parameter are used in line inversion mode.
  // * 4th parameter to 6th parameter are used in frame inversion mode.
  // * Frame rate=fosc/((RTNC + 20) x (LINE + FPC + BPC))
  // * 1 < FPC(front porch) + BPC(back porch) ; Back porch ?0
  //Note: fosc = 333kHz
  SPI_sendCommand(ST7735_FRMCTR3);//In partial mode + Full colors
  SPI_sendData(0x02);//RTNC: set 1-line period
  SPI_sendData(0x35);//FPC:  front porch
  SPI_sendData(0x36);//BPC:  back porch
  SPI_sendData(0x02);//RTND: set 1-line period
  SPI_sendData(0x35);//FPD:  front porch
  SPI_sendData(0x36);//BPD:  back porch

  //INVCTR (B4h): Display Inversion Control
  SPI_sendCommand(ST7735_INVCTR);
  SPI_sendData(0x07);
  // 0000 0ABC
  // |||| ||||-- NLC: Inversion setting in full Colors partial mode
  // |||| |||         (0=Line Inversion, 1 = Frame Inversion)
  // |||| |||--- NLB: Inversion setting in idle mode
  // |||| ||          (0=Line Inversion, 1 = Frame Inversion)
  // |||| ||---- NLA: Inversion setting in full Colors normal mode
  // |||| |----- Unused: 0

  //PWCTR1 (C0h): Power Control 1
  SPI_sendCommand(ST7735_PWCTR1);
  SPI_sendData(0x02);// VRH[4:0] (0-31) Sets GVDD
                     // VRH=0x00 => GVDD=5.0v
                     // VRH=0x1F => GVDD=3.0v
                     // Each tick is a variable step:
                     // VRH[4:0] |  VRH | GVDD
                     //   00000b | 0x00 | 5.00v
                     //   00001b | 0x01 | 4.75v
                     //   00010b | 0x02 | 4.70v <<<<<
                     //   00011b | 0x03 | 4.65v
                     //   00100b | 0x04 | 4.60v
                     //   00101b | 0x05 | 4.55v
                     //   00110b | 0x06 | 4.50v
                     //   00111b | 0x07 | 4.45v
                     //   01000b | 0x08 | 4.40v
                     //   01001b | 0x09 | 4.35v
                     //   01010b | 0x0A | 4.30v
                     //   01011b | 0x0B | 4.25v
                     //   01100b | 0x0C | 4.20v
                     //   01101b | 0x0D | 4.15v
                     //   01110b | 0x0E | 4.10v
                     //   01111b | 0x0F | 4.05v
                     //   10000b | 0x10 | 4.00v
                     //   10001b | 0x11 | 3.95v
                     //   10010b | 0x12 | 3.90v
                     //   10011b | 0x13 | 3.85v
                     //   10100b | 0x14 | 3.80v
                     //   10101b | 0x15 | 3.75v
                     //   10110b | 0x16 | 3.70v
                     //   10111b | 0x17 | 3.65v
                     //   11000b | 0x18 | 3.60v
                     //   11001b | 0x19 | 3.55v
                     //   11010b | 0x1A | 3.50v
                     //   11011b | 0x1B | 3.45v
                     //   11100b | 0x1C | 3.40v
                     //   11101b | 0x1D | 3.35v
                     //   11110b | 0x1E | 3.25v
                     //   11111b | 0x1F | 3.00v
  SPI_sendData(0x02);// 010i i000
                     // |||| ||||-- Unused: 0
                     // |||| |----- IB_SEL0:
                     // ||||------- IB_SEL1:
                     // |||-------- Unused: 010
                     // IB_SEL[1:0] | IB_SEL | AVDD
                     //         00b | 0x00   | 2.5µA   <<<<<
                     //         01b | 0x01   | 2.0µA
                     //         10b | 0x02   | 1.5µA
                     //         11b | 0x03   | 1.0µA

                     //PWCTR2 (C1h): Power Control 2
                     // * Set the VGH and VGL supply power level
                     //Restriction: VGH-VGL <= 32V
  SPI_sendCommand(ST7735_PWCTR2);
  SPI_sendData(0xC5);// BT[2:0] (0-15) Sets GVDD
                     // BT[2:0] |    VGH      |     VGL
                     //    000b | 4X |  9.80v | -3X |  -7.35v
                     //    001b | 4X |  9.80v | -4X |  -9.80v
                     //    010b | 5X | 12.25v | -3X |  -7.35v
                     //    011b | 5X | 12.25v | -4X |  -9.80v
                     //    100b | 5X | 12.25v | -5X | -12.25v
                     //    101b | 6X | 14.70v | -3X |  -7.35v   <<<<<
                     //    110b | 6X | 14.70v | -4X |  -9.80v
                     //    111b | 6X | 14.70v | -5X | -12.25v

                     //PWCTR3 (C2h): Power Control 3 (in Normal mode/ Full colors)
                     // * Set the amount of current in Operational amplifier in
                     //   normal mode/full colors.
                     // * Adjust the amount of fixed current from the fixed current
                     //   source in the operational amplifier for the source driver.
                     // * Set the Booster circuit Step-up cycle in Normal mode/ full
                     //   colors.
  SPI_sendCommand(ST7735_PWCTR3);
  SPI_sendData(0x0D);// AP[2:0] Sets Operational Amplifier Bias Current
                     // AP[2:0] | Function
                     //    000b | Off
                     //    001b | Small
                     //    010b | Medium Low
                     //    011b | Medium
                     //    100b | Medium High
                     //    101b | Large          <<<<<
                     //    110b | reserved
                     //    111b | reserved
  SPI_sendData(0x00);// DC[2:0] Booster Frequency
                     // DC[2:0] | Circuit 1 | Circuit 2,4
                     //    000b | BCLK / 1  | BCLK / 1  <<<<<
                     //    001b | BCLK / 1  | BCLK / 2
                     //    010b | BCLK / 1  | BCLK / 4
                     //    011b | BCLK / 2  | BCLK / 2
                     //    100b | BCLK / 2  | BCLK / 4
                     //    101b | BCLK / 4  | BCLK / 4
                     //    110b | BCLK / 4  | BCLK / 8
                     //    111b | BCLK / 4  | BCLK / 16

                     //PWCTR4 (C3h): Power Control 4 (in Idle mode/ 8-colors)
                     // * Set the amount of current in Operational amplifier in
                     //   normal mode/full colors.
                     // * Adjust the amount of fixed current from the fixed current
                     //   source in the operational amplifier for the source driver.
                     // * Set the Booster circuit Step-up cycle in Normal mode/ full
                     //   colors.
  SPI_sendCommand(ST7735_PWCTR4);
  SPI_sendData(0x8D);// AP[2:0] Sets Operational Amplifier Bias Current
                     // AP[2:0] | Function
                     //    000b | Off
                     //    001b | Small
                     //    010b | Medium Low
                     //    011b | Medium
                     //    100b | Medium High
                     //    101b | Large          <<<<<
                     //    110b | reserved
                     //    111b | reserved
  SPI_sendData(0x1A);// DC[2:0] Booster Frequency
                     // DC[2:0] | Circuit 1 | Circuit 2,4
                     //    000b | BCLK / 1  | BCLK / 1
                     //    001b | BCLK / 1  | BCLK / 2
                     //    010b | BCLK / 1  | BCLK / 4  <<<<<
                     //    011b | BCLK / 2  | BCLK / 2
                     //    100b | BCLK / 2  | BCLK / 4
                     //    101b | BCLK / 4  | BCLK / 4
                     //    110b | BCLK / 4  | BCLK / 8
                     //    111b | BCLK / 4  | BCLK / 16

                     //PPWCTR5 (C4h): Power Control 5 (in Partial mode/ full-colors)
                     // * Set the amount of current in Operational amplifier in
                     //   normal mode/full colors.
                     // * Adjust the amount of fixed current from the fixed current
                     //   source in the operational amplifier for the source driver.
                     // * Set the Booster circuit Step-up cycle in Normal mode/ full
                     //   colors.
  SPI_sendCommand(ST7735_PWCTR5);
  SPI_sendData(0x8D);// AP[2:0] Sets Operational Amplifier Bias Current
                     // AP[2:0] | Function
                     //    000b | Off
                     //    001b | Small
                     //    010b | Medium Low
                     //    011b | Medium
                     //    100b | Medium High
                     //    101b | Large          <<<<<
                     //    110b | reserved
                     //    111b | reserved
  SPI_sendData(0xEE);// DC[2:0] Booster Frequency
                     // DC[2:0] | Circuit 1 | Circuit 2,4
                     //    000b | BCLK / 1  | BCLK / 1
                     //    001b | BCLK / 1  | BCLK / 2
                     //    010b | BCLK / 1  | BCLK / 4
                     //    011b | BCLK / 2  | BCLK / 2
                     //    100b | BCLK / 2  | BCLK / 4
                     //    101b | BCLK / 4  | BCLK / 4
                     //    110b | BCLK / 4  | BCLK / 8  <<<<<
                     //    111b | BCLK / 4  | BCLK / 16

                     //VMCTR1 (C5h): VCOM Control 1
  SPI_sendCommand(ST7735_VMCTR1);
  SPI_sendData(0x51);// Default: 0x51 => +4.525
                     // VMH[6:0] (0-100) Sets VCOMH
                     // VMH=0x00 => VCOMH= +2.5v
                     // VMH=0x64 => VCOMH= +5.0v
  SPI_sendData(0x4D);// Default: 0x4D => -0.575
                     // VML[6:0] (4-100) Sets VCOML
                     // VML=0x04 => VCOML= -2.4v
                     // VML=0x64 => VCOML=  0.0v

                     //GMCTRP1 (E0h): Gamma ‘+’polarity Correction Characteristics Setting
  SPI_sendCommand(ST7735_GAMCTRP1);
  SPI_sendData(0x0a);
  SPI_sendData(0x1c);
  SPI_sendData(0x0c);
  SPI_sendData(0x14);
  SPI_sendData(0x33);
  SPI_sendData(0x2b);
  SPI_sendData(0x24);
  SPI_sendData(0x28);
  SPI_sendData(0x27);
  SPI_sendData(0x25);
  SPI_sendData(0x2C);
  SPI_sendData(0x39);
  SPI_sendData(0x00);
  SPI_sendData(0x05);
  SPI_sendData(0x03);
  SPI_sendData(0x0d);

                     //GMCTRN1 (E1h): Gamma ‘-’polarity Correction Characteristics Setting
  SPI_sendCommand(ST7735_GAMCTRN1);
  SPI_sendData(0x0a);
  SPI_sendData(0x1c);
  SPI_sendData(0x0c);
  SPI_sendData(0x14);
  SPI_sendData(0x33);
  SPI_sendData(0x2b);
  SPI_sendData(0x24);
  SPI_sendData(0x28);
  SPI_sendData(0x27);
  SPI_sendData(0x25);
  SPI_sendData(0x2D);
  SPI_sendData(0x3a);
  SPI_sendData(0x00);
  SPI_sendData(0x05);
  SPI_sendData(0x03);
  SPI_sendData(0x0d);

                     //COLMOD (3Ah): Interface Pixel Format
                     // * This command is used to define the format of RGB picture
                     //   data, which is to be transferred via the MCU interface.
  SPI_sendCommand(ST7735_COLMOD);
  SPI_sendData(0x06);// Default: 0x06 => 18-bit/pixel
                     // IFPF[2:0] MCU Interface Color Format
                     // IFPF[2:0] | Format
                     //      000b | reserved
                     //      001b | reserved
                     //      010b | reserved
                     //      011b | 12-bit/pixel
                     //      100b | reserved
                     //      101b | 16-bit/pixel
                     //      110b | 18-bit/pixel   <<<<<
                     //      111b | reserved

                     //DISPON (29h): Display On
                     // * This command is used to recover from DISPLAY OFF mode. Output
                     //   from the Frame Memory is enabled.
                     // * This command makes no change of contents of frame memory.
                     // * This command does not change any other status.
                     // * The delay time between DISPON and DISPOFF needs 120ms at least
  SPI_sendCommand(ST7735_DISPON);//Display On
  delay(1);

  //MADCTL (36h): Memory Data Access Control
  SPI_sendCommand(ST7735_MADCTL);
  SPI_sendData(0x40);// YXVL RH--
                     // |||| ||||-- Unused: 0
                     // |||| ||---- MH: Horizontal Refresh Order
                     // |||| |        0 = left to right
                     // |||| |        1 = right to left
                     // |||| |----- RGB: RGB vs BGR Order
                     // ||||          0 = RGB color filter panel
                     // ||||          1 = BGR color filter panel
                     // ||||------- ML: Vertical Refresh Order
                     // |||           0 = top to bottom
                     // |||           1 = bottom to top
                     // |||-------- MV: Row / Column Exchange
                     // ||--------- MX: Column Address Order  <<<<<
                     // |---------- MY: Row Address Order

  }
//============================================================================
void Set_LCD_for_write_at_X_Y(uint8_t x, uint8_t y)
  {
  //CASET (2Ah): Column Address Set
  // * The value of XS [15:0] and XE [15:0] are referred when RAMWR
  //   command comes.
  // * Each value represents one column line in the Frame Memory.
  // * XS [15:0] always must be equal to or less than XE [15:0]
  SPI_sendCommand(ST7735_CASET); //Column address set
  //Write the parameters for the "column address set" command
  SPI_sendData(0x00);     //Start MSB = XS[15:8]
  SPI_sendData(0x02 + x); //Start LSB = XS[ 7:0]
  SPI_sendData(0x00);     //End MSB   = XE[15:8]
  SPI_sendData(0x81);     //End LSB   = XE[ 7:0]
  //Write the "row address set" command to the LCD
  //RASET (2Bh): Row Address Set
  // * The value of YS [15:0] and YE [15:0] are referred when RAMWR
  //   command comes.
  // * Each value represents one row line in the Frame Memory.
  // * YS [15:0] always must be equal to or less than YE [15:0]
  SPI_sendCommand(ST7735_RASET); //Row address set
  //Write the parameters for the "row address set" command
  SPI_sendData(0x00);     //Start MSB = YS[15:8]
  SPI_sendData(0x01 + y); //Start LSB = YS[ 7:0]
  SPI_sendData(0x00);     //End MSB   = YE[15:8]
  SPI_sendData(0x80);     //End LSB   = YE[ 7:0]
  //Write the "write data" command to the LCD
  //RAMWR (2Ch): Memory Write
  SPI_sendCommand(ST7735_RAMWR); //write data
  }
//============================================================================
void Fill_LCD(uint8_t R, uint8_t G, uint8_t B)
  {
  register int
    i;
  Set_LCD_for_write_at_X_Y(0, 0);

  //Fill display with a given RGB value
  for (i = 0; i < (128 * 128); i++)
    {
    SPI_sendData(B); //Blue
    SPI_sendData(G); //Green
    SPI_sendData(R); //Red
    }
  }
//============================================================================
void Put_Pixel(uint8_t x, uint8_t y, uint8_t R, uint8_t G, uint8_t B)
  {
  Set_LCD_for_write_at_X_Y(x, y);
  //Write the single pixel's worth of data
  SPI_sendData(B); //Blue
  SPI_sendData(G); //Green
  SPI_sendData(R); //Red
  }
//============================================================================
// From: http://en.wikipedia.org/wiki/Midpoint_circle_algorithm
void LCD_Circle(uint8_t x0, uint8_t y0, uint8_t radius, uint8_t R, uint8_t G, uint8_t B)
  {
  uint8_t x = radius;
  uint8_t y = 0;
  int16_t radiusError = 1 - (int16_t) x;

  while (x >= y)
    {
    //11 O'Clock
    Put_Pixel(x0 - y, y0 + x, R, G, B);
    //1 O'Clock
    Put_Pixel(x0 + y, y0 + x, R, G, B);
    //10 O'Clock
    Put_Pixel(x0 - x, y0 + y, R, G, B);
    //2 O'Clock
    Put_Pixel(x0 + x, y0 + y, R, G, B);
    //8 O'Clock
    Put_Pixel(x0 - x, y0 - y, R, G, B);
    //4 O'Clock
    Put_Pixel(x0 + x, y0 - y, R, G, B);
    //7 O'Clock
    Put_Pixel(x0 - y, y0 - x, R, G, B);
    //5 O'Clock
    Put_Pixel(x0 + y, y0 - x, R, G, B);

    y++;
    if (radiusError < 0)
      radiusError += (int16_t)(2 * y + 1);
    else
      {
      x--;
      radiusError += 2 * (((int16_t) y - (int16_t) x) + 1);
      }
    }
  }
//============================================================================
void setup()
  {
  // LCD SPI & control lines
  //   ARD   | Port | LCD
  // --------+------+-------------------------
  //  #8/D8  |  PB0 | LCD_RS
  //  #9/D9  |  PB1 | LCD_RESET
  // #10/D10 |  PB2 | LCD_CS_NOT (or SPI SS)
  // #11/D11 |  PB3 | LCD_MOSI (hardware SPI)
  // #12/D12 |  PB4 | not used (would be MISO)
  // #13/D13 |  PB5 | LCD_SCK (hardware SPI)
  DDRB |= 0x2F;

  //Drive the ports to a reasonable starting state.
  CLR_RESET;
  CLR_RS;
  SET_CS;
  CLR_MOSI;
  CLR_SCK;

#if(HARDWARE_SPI)
  // initialize SPI. By default the clock is 4MHz. The chip is good to 10 MHz
  SPI.begin();
  //Bump the clock to 8MHz. Appears to be the maximum.
  SPI.beginTransaction(SPISettings(8000000, MSBFIRST, SPI_MODE0));
#endif
  }
//============================================================================
void loop()
  {
  uint8_t
    i;
  uint8_t
    j;
  uint8_t
    x;
  uint8_t
    sub_x;
  uint8_t
    y;
  uint8_t
    sub_y;

  //Initialize the LCD controller
  Initialize_LCD();

  //Fill display with a given RGB value
  Fill_LCD(0x00,0x00,0xFF);

  //Draw a cyan circle
  LCD_Circle(64, 64, 63,0x00,0xFF,0xFF);
  //Draw a green circle
  LCD_Circle(21, 64, 20,0x00,0xFF,0x00);
  //Draw a white circle
  LCD_Circle(64, 64, 20,0xFF,0xFF,0xFF);
  //Draw a red circle
  LCD_Circle(107, 64, 20,0xFF,0x00,0x00);
  //Draw a purple circle
  LCD_Circle(64, 107, 16,0xFF,0x00,0xFF);
  //Draw a orange circle
  LCD_Circle(64, 21, 14,0xFF,0xA5,0x00);

  delay(1000);
  Fill_LCD(0x00,0x00,0x00);
  for(i=2;i<60;i+=2)
    {
    LCD_Circle(i+2, 64, i,i<<2,0xff-(i<<2),0x00);
    }
  delay(1000);

  //Write a 8x8 checkerboard
  for(x=0;x<=15;x++)
    {
    for(y=0;y<=15;y++)
      {
      for(sub_x=0;sub_x<=7;sub_x++)
        for(sub_y=0;sub_y<=7;sub_y++)
          if(((x&0x01)&&!(y&0x01)) || (!(x&0x01)&&(y&0x01)))
            Put_Pixel((x<<3)+sub_x,(y<<3)+sub_y, 0x00, 0x00, 0x00);
          else
            Put_Pixel((x<<3)+sub_x,(y<<3)+sub_y, 0xFF, 0xFF-(x<<4), 0xFF-(y<<4));
      }
    }
  delay(1000);
  } // void loop()
//============================================================================
Putting it all together:


And a video showing it in action:
https://www.youtube.com/watch?v=PXzmSylwjdY
Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.
 
Last edited:
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