An Analogue Meter Emulator
with a CG9A01 TFT

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'                                  Let's find out together what makes a PIC Tick!

'

' An analogue meter movement emulator, using a circular CG9A01 Graphic LCD on a PIC18FxxK40 device.

' A 10-bit ADC input is used to move the meter's needle on the LCD.

'

' Written by Les Johnson for the Positron8 BASIC compiler.

' https://sites.google.com/view/rosetta-tech/home

'

    Device = 18F26K40                                 ' Tell the compiler what device to compile for

    Declare Xtal = 64                                 ' Tell the compiler what frequency the device is operating at (in MHz)

    Declare Float_Display_Type = Fast                 ' Tell the compiler to use the faster Floating Point to ASCII library sub

    Declare Auto_Heap_Strings = On                    ' Make Strings Heap types, so they get placed after standard variables

    Declare Auto_Variable_Bank_Cross = On             ' Make sure all multi-byte variables remain within the same RAM bank

'

' Setup USART1 for debugging

'

    Declare Hserial1_Baud = 9600

    Declare HRSOut1_Pin = PORTC.6

'

' Define the pins used for the CG9A01 LCD display

'

$define CG9A01_CLK_Pin  PORTC.3                                 ' Connects to the CG9A01 CLK pin (named SCL on some displays)

$define CG9A01_CLK_PPS_Pin Pin_C3                               ' Define the CLK Pin to use for PPS

$define CG9A01_DTA_Pin  PORTC.5                                 ' Connects to the CG9A01 DTA pin (named SDI on some displays)

$define CG9A01_DTA_PPS_Pin Pin_C5                               ' Define the DTA Pin to use for PPS

$define CG9A01_CS_Pin   PORTC.2                                 ' Connects to the CG9A01 CS pin

$define CG9A01_DC_Pin   PORTC.1                                 ' Connects to the CG9A01 DC pin

$define CG9A01_RST_Pin  PORTC.0                                 ' Connects to the CG9A01 Reset pin

$define CG9A01_BLK_Pin  PORTB.0                                 ' Connects to the CG9A01 BLK (Backlight) pin

'

' Setup the ADC input pin and SFR

'

$define ADC_Pin PORTA.0                                         ' The pin to use for the ADC input

$define ADC_SFR ANSELA.0                                        ' The ADC analogue SFR and bit, for the Port and Pin used

$define ADC_Pin_Analogue() ADC_SFR = 1                          ' A meta-macro to set the ADC channel pin as analogue

$define ADC_Pin_Digital()  ADC_SFR = 0                          ' A meta-macro to set the ADC channel pin as digital

$define GLCD_Backlight_On() PinHigh CG9A01_BLK_Pin              ' A meta-macro to illuminate the LCD's backlight

$define GLCD_Backlight_Off() PinLow CG9A01_BLK_Pin              ' A meta-macro to extinguish the LCD's backlight

    Include "Tahoma_12.inc"                                     ' Load a font table into the program

    Include "TahomaBold_14.inc"                                 ' Load a font table into the program

    Include "CG9A01.inc"                                        ' Load the CG9A01 LCD library into the program

    Include "HSPI_K40.inc"                                      ' Load the SPI peripheral library into the program

'

' Convert an RGB888 constant value into an RGB565 constant value

'

$define RGB565(r,g,b) $eval ((((r) >> 3) & 0x1F) << 11) | ((((g) >> 2) & 0x3F) << 5) | (((b) >> 3) & 0x1F)

$define clBackGnd RGB565(200, 190, 190)                          ' The meter's background colour

'

' Create global constants here

'

$define cCENTER_X    $eval (cCG9A_Width / 2)                     ' The center X position of display

$define cCENTER_Y    $eval (cCG9A_Height / 2)                    ' The center Y position of the display

$define cPI          3.1415926                                   ' The value for PI

$define cPI_Div180   0.0174532                                   ' Used to convert degrees to radians (PI / 180)

$define cNeedle_MinPos 230                                       ' The maximum position of the meter's dial

$define cNeedle_MaxPos 270                                       ' The maximum position of the meter's dial

$define cNeedlePos     220                                       ' The default position of the needle

$define cNeedleRadius  120                                       ' The radius of the needle

$define cNeedleSpeed   10                                        ' The speed that the needle returns to the left

$define cPivotX        cCENTER_X                                 ' The needle's pivot X position

$define cPivotY        $eval (cCENTER_Y + 50)                    ' The needle's pivot Y position

$define cPivotRadius   8                                         ' The needle's pivot radius

'

' Create global variables here

'

    Dim wADC_Value As SWord                                      ' Holds the ADC reading

'--------------------------------------------------------------------------------------------

' The main program starts here

' Move the meter based upon the reading of the 10-bit ADC

'

Main:

    Setup()                                                       ' Setup the program and any peripherals

    Do                                                            ' Create a loop

        wADC_Value = ADC_Read10(0)                                ' Take a reading from the ADC

        Move_Meter(wADC_Value)                                    ' Move the meter's needle based upon it

        DelayMS 100                                               ' Wait before moving the needle again

    Loop                                                          ' Do it forever

'--------------------------------------------------------------------------------------------

' Move the meter's needle

' Input     : pValue holds the scaled 10-bit ADC reading (0 to 1023)

' Output    : None

' Notes     : If the needle does not need to move, it is not re-drawn

'

Proc Move_Meter(pValue As SWord)

Static Dim wNeedleValue As Word = cNeedle_MinPos                   ' Start with a known needle angle

Static Dim wPrevValue   As Word = 0                                ' Holds the previous needle's value

    Dim wAngle          As Word                                    ' Holds the needle's angle based upon the scaling of pValue

    wAngle = Scale16S(pValue, 0, 1023, cNeedle_MinPos, cNeedle_MaxPos) ' Scale the 10-bit analogue input to the needle position

'
' If the required value is greater than current needle position, move quickly
'
    If wAngle > wNeedleValue Then                                  

        wNeedleValue = wAngle

    ElseIf wAngle < wNeedleValue Then                      ' If the needle value is lower, move more slowly to simulate damping

        wNeedleValue = wNeedleValue - cNeedleSpeed                ' Decrease the value gradually

        If wNeedleValue < wAngle Then                              ' \

            wNeedleValue = wAngle                                  ' | Make sure the needle does not overshoot

        EndIf                                                      ' /

    EndIf

    If wNeedleValue <> wPrevValue Then                             ' Has the value changed for the needle's movement?

        Draw_Needle(wNeedleValue)                                  ' Yes. So update the needle position

        GLCD_FillCircle(cPivotX, cPivotY, cPivotRadius, clBlack)   ' Re-Draw the needle's pivot

    EndIf

    wPrevValue = wNeedleValue                                      ' Keep a copy of the needle's value

EndProc

'--------------------------------------------------------------------------------------------

' Draw the moving needle, without the tip arrow

' Input     : pValue holds the position the needle will move to

' Output    : None

' Notes     : Draws a double thickness line for the needle to make it more visible

'

Proc Draw_NeedleOnly(pValue As Word)

Symbol cCENTER_Y_50    = (cCENTER_Y + 50)

Global Dim fNeedlePos  As Float Access Shared                       ' Holds the needle's position

Global Dim fCosValue   As Float Access Shared

Global Dim fSinValue   As Float Access Shared

Static Dim wNdl1_PrevX As Word = cCENTER_X

Static Dim wNdl1_PrevY As Word = cCENTER_Y_50

    Dim wNdl1X         As Word

    Dim wNdl1Y         As Word

    fNeedlePos = (pValue * cPI_Div180) * 1.8                         ' \ Convert degrees to radians

    fNeedlePos = fNeedlePos - cPI                                    ' /

    fCosValue = Cos(fNeedlePos)                                      ' \

    fSinValue = Sin(fNeedlePos)                                      ' |

    wNdl1X = cPivotX + (cNeedleRadius * fCosValue)                   ' | Calculate the position of the needle's tip

    wNdl1Y = cPivotY + (cNeedleRadius * fSinValue)                   ' /

    GLCD_Line(cPivotX, cPivotY, wNdl1_PrevX, wNdl1_PrevY, clBackGnd)     ' \ Erase the old needle

    GLCD_Line(cPivotX, cPivotY, wNdl1_PrevX + 1, wNdl1_PrevY, clBackGnd) ' /

'

' Place texts on the meter's dial

'

    GLCD_PenColour(clBlack)                                           ' Choose the texts ink colour

    GLCD_SetFont(TahomaBold_14)                                       ' Choose the font to use for the "Meter" text

    GLCD_PrintAtCentre(cPivotY - 40, "Meter")                         ' Draw text above the pivot

    GLCD_SetFont(Tahoma12)                                            ' Choose the font to use for the texts 

    Print At 72, 25, "Min",                                           ' \ Draw the "Min" and "Max" texts on the dial

          At 72, 182, "Max"                                           ' /

    GLCD_Line(cPivotX, cPivotY, wNdl1X, wNdl1Y, clBlack)              ' \ Draw the needle

    GLCD_Line(cPivotX, cPivotY, wNdl1X + 1, wNdl1Y, clBlack)          ' /

    wNdl1_PrevX = wNdl1X                                              ' \

    wNdl1_PrevY = wNdl1Y                                              ' / Store the X and Y positions of the needle

EndProc

'--------------------------------------------------------------------------------------------

' Draw the moving needle, with its tip arrow

' Input     : pValue holds the position the needle will move to

' Output    : None

' Notes     : None

'

Proc Draw_Needle(pValue As Word)

Symbol cCENTER_Y_50     = (cCENTER_Y + 50)

Symbol cCENTER_Y_30     = (cCENTER_Y + 30)

Symbol cRadius_Min_15   = (cNeedleRadius - 15)

Symbol cRadius_Min_90   = (cNeedleRadius - 90)

Global Dim fNeedlePos   As Float Access Shared                         ' Holds the needle's position

Global Dim fCosValue    As Float Access Shared

Global Dim fSinValue    As Float Access Shared

Static Dim wNdl1_PrevX  As Word = cCENTER_X

Static Dim wNdl1_PrevY  As Word = cCENTER_Y_50

Static Dim wNdl_PrevLTipX As Word = cCENTER_X

Static Dim wNdl_PrevLTipY As Word = cCENTER_Y_50

Static Dim wNdl_PrevRTipX As Word = cCENTER_X

Static Dim wNdl_PrevRTipY As Word = cCENTER_Y_50

    Dim wNdl1X     As Word

    Dim wNdl1Y     As Word

    Dim wNdl_LTipX As Word

    Dim wNdl_LTipY As Word

    Dim wNdl_RTipX As Word

    Dim wNdl_RTipY As Word

    fNeedlePos = (pValue * cPI_Div180) * 1.8                            ' \ Convert degrees to radians

    fNeedlePos = fNeedlePos - cPI                                       ' /

    fCosValue = Cos(fNeedlePos)                                         ' \

    fSinValue = Sin(fNeedlePos)                                         ' |

    wNdl1X = cPivotX + (cNeedleRadius * fCosValue)                      ' | Calculate the Needle position

    wNdl1Y = cPivotY + (cNeedleRadius * fSinValue)                      ' /

    fCosValue = Cos(fNeedlePos - 0.05)                                  ' \

    fSinValue = Sin(fNeedlePos - 0.05)                                  ' |

    wNdl_LTipX = cPivotX + (cRadius_Min_15 * fCosValue)                 ' | Calculate the Needle tip triangle left

    wNdl_LTipY = cPivotY + (cRadius_Min_15 * fSinValue)                 ' /

    fCosValue = Cos(fNeedlePos + 0.05)                                  ' \

    fSinValue = Sin(fNeedlePos + 0.05)                                  ' |

    wNdl_RTipX = cPivotX + (cRadius_Min_15 * fCosValue)                 ' | Calculate the Needle tip triangle right

    wNdl_RTipY = cPivotY + (cRadius_Min_15 * fSinValue)                 ' /

    GLCD_Line(cPivotX, cPivotY, wNdl1_PrevX, wNdl1_PrevY, clBackGnd)    ' Erase the old needle

'
' Erase the tip triangle
'
    GLCD_FillTriangle(wNdl1_PrevX, wNdl1_PrevY, wNdl_PrevLTipX, wNdl_PrevLTipY, wNdl_PrevRTipX, wNdl_PrevRTipY, clBackGnd) 

'

' Place texts on the meter's dial

'

    GLCD_PenColour(clBlack)                                             ' Choose the texts ink colour

    GLCD_SetFont(TahomaBold_14)                                         ' Choose the font to use for the "Meter" text

    GLCD_PrintAtCentre(cPivotY - 40, "Meter")                           ' Draw text above the pivot

    GLCD_SetFont(Tahoma12)                                              ' Choose the font to use for the texts 

    Print At 72, 25, "Min",                                             ' \ Draw the "Min" and "Max" texts on the dial

          At 72, 182, "Max"                                             ' /

    GLCD_Line(cPivotX, cPivotY, wNdl1X, wNdl1Y, clBlack)                ' Draw the needle

    GLCD_FillTriangle(wNdl1X, wNdl1Y, wNdl_LTipX, wNdl_LTipY, wNdl_RTipX, wNdl_RTipY, clBlack)' Draw the tip triangle

    wNdl1_PrevX = wNdl1X                                                ' \

    wNdl1_PrevY = wNdl1Y                                                ' |

    wNdl_PrevLTipX = wNdl_LTipX                                         ' |  Store the previous needle position

    wNdl_PrevLTipY = wNdl_LTipY                                         ' |

    wNdl_PrevRTipX = wNdl_RTipX                                         ' |

    wNdl_PrevRTipY = wNdl_RTipY                                         ' /                                           
EndProc

'--------------------------------------------------------------------------------------------

' Draw the meter's dial

' Input     : None

' Output    : None

' Notes     : None

'

Proc Draw_Dial()

Symbol cBlipPos       = (cNeedleRadius + 15)

Global Dim fNeedlePos As Float Access Shared                   ' Holds the needle's position

Global Dim fCosValue  As Float Access Shared

Global Dim fSinValue  As Float Access Shared

    Dim wArc_X        As Word

    Dim wArc_Y        As Word

    Dim bRadian       As Byte

    GLCD_Cls(clBackGnd)                                        ' \

    GLCD_Circle(cCENTER_X, cCENTER_Y, 118, clGray2)            ' |

    GLCD_Circle(cCENTER_X, cCENTER_Y, 117, clBlack)            ' | Create the dial's edges

    GLCD_Circle(cCENTER_X, cCENTER_Y, 116, clBlack)            ' |

    GLCD_Circle(cCENTER_X, cCENTER_Y, 115, clGray2)            ' /

    For bRadian = 30 To 44 Step 5                              ' \

        fNeedlePos = (bRadian * cPI_Div180) * 1.8              ' |

        fNeedlePos = fNeedlePos - cPI                          ' |

        fCosValue = Cos(fNeedlePos)                            ' | Calculate the positions for the dial's beginning green blips

        fSinValue = Sin(fNeedlePos)                            ' |

        wArc_X = (cPivotX  + (cBlipPos * fCosValue))           ' |

        wArc_Y = (cPivotY  + (cBlipPos * fSinValue))           ' /

        GLCD_FillCircle(wArc_X, wArc_Y, 4, clGreen)            ' Draw a green blip of the dial 

    Next                                                                    

    For bRadian = 45 To 59 Step 5                              ' \

        fNeedlePos = (bRadian * cPI_Div180) * 1.8              ' |

        fNeedlePos = fNeedlePos - cPI                          ' |

        fCosValue = Cos(fNeedlePos)                            ' | Calculate the positions for the dial's beginning black blips

        fSinValue = Sin(fNeedlePos)                            ' |

        wArc_X = (cPivotX  + (cBlipPos * fCosValue))           ' |

        wArc_Y = (cPivotY  + (cBlipPos * fSinValue))           ' /

        GLCD_FillCircle(wArc_X, wArc_Y, 4, clBlack)            ' Draw a black blip of the dial

    Next                                                                    

    For bRadian = 60 To 74 Step 5                              ' \

        fNeedlePos = (bRadian * cPI_Div180) * 1.8              ' |

        fNeedlePos = fNeedlePos - cPI                          ' |

        fCosValue = Cos(fNeedlePos)                            ' | Calculate the positions for the dial's ending red blips

        fSinValue = Sin(fNeedlePos)                            ' | 

        wArc_X = (cPivotX  + (cBlipPos * fCosValue))           ' |

        wArc_Y = (cPivotY  + (cBlipPos * fSinValue))           ' /

        GLCD_FillCircle(wArc_X, wArc_Y, 4, clBrightRed)        ' Draw a red blip of the dial

    Next

    GLCD_SetFont(Tahoma12)                                     ' Choose the font to use for the texts

    Print At 72, 25, "Min", 

          At 72, 182, "Max"

EndProc

'-------------------------------------------------------------------------------------------------------------

' Scale one 16-bit signed integer value range to another 16-bit signed integer value range

' Input     : pValueIn holds the value to scale

'           : pInMin is the lower bound of the value's input range

'           : pInMax is the upper bound of the value's input range

'           : pOutMin is the lower bound of the value's target range

'           : pOutMax is the upper bound of the value's target range

' Output    : Returns the scaled result

' Notes     : None

'

Proc Scale16S(pValueIn As SDword, pInMin As SWord, pInMax As SWord, pOutMin As SWord, pOutMax As SWord), SWord

    Result = (((pValueIn - pInMin) * (pOutMax - pOutMin)) / (pInMax - pInMin)) + pOutMin

EndProc

'--------------------------------------------------------------------------------------------

' Setup the program and any peripherals

' Input     : None

' Output    : None

' Notes     : None

'

Proc Setup()

'

' Setup the SPI1 peripheral (if used)

'

$ifndef _cSOFTWARE_SPI_                                   ' Is the CG9A01 library using bit-bashed SPI routines?

    PPS_Unlock()                                          ' No. So Unlock the PPS for the SPI peripheral

    Set_PPSForSCK1(CG9A01_CLK_PPS_Pin)                    ' Setup the SPI1 peripheral's PPS, CLK for the LCD's SCK pin

    Set_PPSForSDO1(CG9A01_DTA_PPS_Pin)                    ' Setup the SPI1 peripheral's PPS, SDO pin for the LCD's DTA pin

    Set_PPSForSDI1(Pin_C4)                                ' Setup the SPI1 peripheral's PPS, SDI pin

    HSPI1_Init_Mode0_MaxMHz()                             ' Setup the SPI1 peripheral to operate in Mode 0 at its fastest speed

$endif

    GLCD_Init()                                           ' Initialise the CG9A01 LCD

'

' Extinguish the LCD's backlight. So that it does not show the initial dial being drawn

'
    GLCD_Backlight_Off()                                  

    ADC_Setup()                                           ' Initialise the ADC

    GLCD_Rotate(2)                                        ' Rotate the display

    GLCD_Cls(clBackGnd)                                   ' Clear the LCD with the background colour

    GLCD_SetFont(TahomaBold_14)                           ' Choose the default font to use for the texts

    GLCD_PaperColour(clBackGnd)                           ' Choose the text's background colour

    GLCD_PenColour(clBlack)                               ' Choose the text's ink colour

    Draw_Dial()                                           ' Draw the meter's dial

    Draw_Needle(cNeedlePos)                               ' Draw the meter's needle

    GLCD_FillCircle(cPivotX, cPivotY, cPivotRadius, clBlack) ' Draw the needle's pivot

    GLCD_Backlight_On()                                   ' Illuminate the LCD's backlight

EndProc

'------------------------------------------------------------------------------------------------------------

' Setup the ADC peripheral on a PIC18FxxK40 device

' Input     : None

' Output    : None

' Notes     : Set for 10-bit operation

'

Proc ADC_Setup()

    ADLTHL  = %00000000

    ADLTHH  = %00000000

    ADUTHL  = %00000000

    ADUTHH  = %00000000

    ADSTPTL = %00000000

    ADSTPTH = %00000000

    ADRPT   = %00000000

    ADPCH   = %00000000

    ADCAP   = %00000000

    ADCON0  = %10000100                                    ' Right justify for 10-bit operation. ADCS is ADCLK

    ADCON1  = %00000000

    ADCON2  = %00000000                                    ' Basic_mode

    ADCON3  = %00000000

    ADSTAT  = %00000000

    ADREF   = %00000000                                    ' -Vref is VSS. +Vref is VDD

    ADACT   = %00000000

    ADCLK   = %00001111                                    ' fOSC/32: (FOSC / (2 * (n + 1)))

    ADACQ   = %00000000

EndProc

'------------------------------------------------------------------------------------------------------------

' Read the ADC on a PIC18F26K40 device

' Input     : pChan holds the ADC channel to read

' Output    : Returns the 10-bit ADC value

' Notes     : Requires the ADFM bit set for right justified 10-bit operation

'

Proc ADC_Read10(pChan As WREG), Word

    ADPCH = pChan                                           ' Load the channel into the relevant SFR

    ADCON0bits_ADON = 1                                     ' Enable the ADC

    DelayUS 100                                             ' A delay before sampling

    ADCON0bits_GO_DONE = 1                                  ' \

    Repeat : Until ADCON0bits_GO_DONE = 0                   ' / Start a sample and wait for it to finish

    Result.Byte1 = ADRESH                                   ' \

    Result.Byte0 = ADRESL                                   ' / Return the sample value

EndProc

'------------------------------------------------------------------------------------------------------------

' Setup the config fuses to use the internal oscillator at 64MHz on PIC18FxxK40 devices

' With pins RA6 and RA7 as general purpose I/O

'

Config_Start

    RSTOSC = HFINTOSC_64MHZ                                  ' HFINTOSC with HFFRQ = 64MHz and CDIV = 1:1

    FEXTOSC = Off                                            ' External Oscillator not enabled

    WDTE = Off                                               ' Watchdog Timer disabled

    CLKOUTEN = Off                                           ' CLKOUT function is disabled

    CSWEN = On                                               ' Writing to NOSC and NDIV is allowed

    FCMEN = Off                                              ' Fail-Safe Clock Monitor disabled

    MCLRE = EXTMCLR                                          ' MCLR pin is MCLR

    PWRTE = On                                               ' Power up timer enabled

    LPBOREN = Off                                            ' ULPBOR disabled

    BOREN = Off                                              ' Brown-out disabled

    BORV = VBOR_245                                          ' Brown-out Reset Voltage (VBOR) set to 2.45V

    ZCD = Off                                                ' ZCD disabled

    PPS1WAY = Off                                            ' PPSLOCK bit can be set and cleared repeatedly

    STVREN = Off                                             ' Stack full/underflow will not cause reset

    Debug = Off                                              ' Background debugger disabled

    XINST = Off                                              ' Extended instruction set disabled

    SCANE = Off                                              ' Scanner module is Not available for use. SCANMD bit is ignored

    LVP = Off                                                ' Low Voltage programming disabled

    WDTCPS = WDTCPS_2                                        ' Watchdog Divider Ratio 1:128 (4 milliseconds)

    WDTCWS = WDTCWS_7                                        ' Watchdog Window always open (100%)

    WDTCCS = LFINTOSC                                        ' WDT reference clock is the 31.2kHz

    WRT0 = Off                                               ' Block 0 (000800-001FFF) not write-protected

    WRT1 = Off                                               ' Block 1 (002000-003FFF) not write-protected

    WRTC = Off                                               ' Configuration registers (300000-30000B) not write-protected

    WRTB = Off                                               ' Boot Block (000000-0007FF) not write-protected

    WRTD = Off                                               ' Data EEPROM not write-protected

    Cp = Off                                                 ' User NVM code protection disabled

    CPD = Off                                                ' Data NVM code protection disabled

    EBTR0 = Off                                              ' Block 0 not protected from table reads executed in other blocks

    EBTR1 = Off                                              ' Block 1 not protected from table reads executed in other blocks

    EBTRB = Off                                              ' Boot Block not protected from table reads in other blocks

Config_End