Originally Posted by
RossWaddell
Now that I'm not using PBP's ADCIN the readings are rock solid.
Well, they were rock solid. Now the readings are varying quite a lot and even with Melanie's 'averaging' code to pick the middle 8 values from 16 it's still jumping around a lot (and still doesn't read 0 when the trim pot wiper is at the GND end). If I measure the voltage reaching pin 6 (AN1) with a voltmeter it seems accurate and steady, varying from +5V to 0. What am I doing wrong now?
Code:
'****************************************************************
'* Name : Nacelle_Steady-On_Lights_12F1840_16Mhz_Int.pbp *
'* Author : Ross A. Waddell *
'* Notice : Copyright (c) 2016 *
'* : All Rights Reserved *
'* Date : 02/02/2016 *
'* Version : 1.0 *
'* Notes : Steady-on nacelle engine lights (TOS Enterprise) *
'* : *
'****************************************************************
' TODO:
' Add gamma correction
' Increase ADC resolution to 1024
' Update PWM frequency/prescaler to use higher resolution
' The PWM/fade works perfectly when **not** connected to a FET
' - if using a FET, the LEDs 'pulse' and blink but don't fade in/out
' - use a 2N2222A transistor
DEFINE OSC 16 ' Set oscillator 16Mhz
' For production version of this code, comment out the line below re:
' LCD debugging and also update config fuses to have code protect on
#DEFINE USE_LCD_FOR_DEBUG ; comment out for non-debug use
' ***************************************************************
' Pin Connections
' ***************************************************************
' VDD -> pin 1 -> +5V
' RA5/Rc -> pin 2 -> EUSART receive
' RA2 -> pin 5 -> 1kohm -> 2N2222A transistor -> LEDs
' RA1 -> pin 6 -> Trim pot input
' RA0/Tx -> pin 7 -> EUSART transmit (LCD)
' VSS -> pin 8 -> GND
' ***************************************************************
' EUSART Settings for Tx/Rc (e.g. LCD)
' ***************************************************************
' > use Mister E PIC Multi-Calc application to get register/DEFINE settings
' > as the values are dependent on the OSC and desired baud rate
DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
DEFINE HSER_CLROERR 1 ' Clear overflow automatically
DEFINE HSER_SPBRG 160 ' 9600 Baud @ 16MHz, -0.08%
' ***************************************************************
' Device Fuses
' ***************************************************************
' PIC chip data sheets can be found here: C:\Program Files\Microchip\MPASM Suite
#CONFIG
__config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF
__config _CONFIG2, _PLLEN_OFF & _STVREN_ON & _BORV_LO & _LVP_OFF
#ENDCONFIG
' ***************************************************************
' Initialization
' ***************************************************************
OSCCON = %01111000 ' 16MHz internal osc
pause 100 ' for EEPROM issue
APFCON.2 = 0 ; Tx on RA0 for LCD display
APFCON.7 = 1 ; Rc on RA5
APFCON.0 = 0 ; CCP1 on RA2
' Some LCD serial modules need inverted data, some do not
' Enable the line below if needed, but for SparkFun SerLCD it should be
' commented out
'BAUDCON.4 = 1 ; Transmit inverted data to the Tx pin
' From Mister E's Multi-Calc (EUSART):
' *****************************************************************
SPBRGH = 1
BAUDCON.3 = 1 ' Enable 16 bit baudrate generator
' *****************************************************************
FVRCON = 0 ' Fixed Voltage Reference is disabled
ANSELA = %00000010 ; Analog on PORTA.1 (AN1) only
'ADCON0 = %00000101 ' ADC (analog-to-digital) is enabled on AN1 (RA1) only
'PAUSEUS 20 ; wait for the analog switch 'glitch' to die down
ADCON1 = %10010000 ; Right-justified results in 10-bits; Fosc/8 as timer;
; VREF is connected to VDD
TRISA = %00100010 ' Make all pins output except for RA1 (trim pot input)
' and RA5 (EUSART Rc)
ADCInVal VAR WORD ; stores ADCIN result read from trim pot
LEDBrVal VAR WORD
FadeInPause CON 25 ; Pause during LED fade in
i VAR WORD
' ***************************************************************
' Set up PWM on CCP1
' ***************************************************************
CCP1CON = %00001100 ; Use CCP1 in PWM mode
' Set duty cycle registers initially to 0
CCP1CON.4 = 0
CCP1CON.5 = 0
CCPR1L = 0
' Use Mister E's PICMultiCalc_1.3.1.exe application (Windows only)
' to determine prescaler and PR2 values for given OSC frequency (e.g. 16Mhz)
' and duty cycle (use 100% to see highest actual value)
' ************************
' CCP1 uses TMR2
' ************************
T2CON = %00000110 ; Timer2 on with 1:16 prescaler
PR2 = 255 ; For 16Mhz OSC the desired output freq of 976.563Hz
; is achieved with this PR2 value (10-bit resolution
; with 1:16 prescaler)
MaxDuty VAR WORD ; According to Darrel:
; MaxDuty = (PR2 + 1) * 4
MaxDuty = (PR2 + 1) * 4 ; 1024
MinDuty CON 0 ; Minimum brightness for this application
MaxADCVal CON 1023 ; 255 for 8-bit; 1023 for 10-bit
compVal VAR WORD ; stores last-changed ADC value
CounterA var BYTE ' Just a BYTE Temporary working variable
DataW var WORD ' Just a WORD Temporary working variable
RawData var WORD [16] ' Array holding ADC Result
#IFDEF USE_LCD_FOR_DEBUG
' Display control codes for SerLCD serial LCD (SparkFun part #LCD-09395)
' (see 'Dropbox\PBP Projects\PIC Datasheets\SerLCD_V2_5 Datasheet.pdf'
' for list of control codes)
LCD_INST CON 254 ' instruction
LCD_CLR CON 1 ' Clear screen
LCD_L1 CON 128 ' LCD line 1
LCD_L2 CON 192 ' LCD line 2
LCD_BR_CMD CON 124 ' command character for adjusting backlight brightness
LCD_BR_LVL CON 140 ' 140==40%
#ENDIF
' Should only need to do this one time to adjust backlight brightness
'#IFDEF USE_LCD_FOR_DEBUG
' HSEROUT [LCD_BR_CMD, LCD_BR_LVL]
' PAUSE 5
'#ENDIF
#IFDEF USE_LCD_FOR_DEBUG
pause 1000
HSEROUT [LCD_INST, LCD_CLR, "LCD Init"]
pause 5
HSEROUT [LCD_INST, LCD_L2, "SerLCD_V2_5"]
pause 500
#ENDIF
GOSUB DO_ADCIN_Chk
LEDBrVal = ADCInVal
compVal = LEDBrVal
'compVal = ADCInVal
'GOSUB Map_VrefInVal_to_PWM_Duty
#IFDEF USE_LCD_FOR_DEBUG
HSEROUT [LCD_INST, LCD_CLR]
pause 5
HSEROUT ["LEDBrVal=",DEC LEDBrVal," "]
pause 500
#ENDIF
' Fade in LED to final brightness
FOR i = 0 to LEDBrVal
CCP1CON.4 = i.0
CCP1CON.5 = i.1
CCPR1L = i >> 2
pause FadeInPause
#IFDEF USE_LCD_FOR_DEBUG
HSEROUT [LCD_INST, LCD_CLR]
pause 5
HSEROUT ["i=",DEC i," "]
#ENDIF
NEXT i
Main:
GOSUB DO_ADCIN_Chk
PAUSE 100
IF ADCInVal <> compVal THEN
#IFDEF USE_LCD_FOR_DEBUG
HSEROUT [LCD_INST, LCD_CLR]
pause 5
HSEROUT ["new ADCInVal", LCD_INST, LCD_L2, DEC ADCInVal, " "]
#ENDIF
LEDBrVal = ADCInVal
compVal = LEDBrVal
gosub ChngLEDBrightness
ENDIF
GOTO Main
'*********** Read ADC or USART Rc inputs *******************************
Do_ADCIN_Chk:
' Stuff 16 Element WORD Array full of ADC values
' ----------------------------------------------
For CounterA=0 to 15
ADCON0 = %00000101 ' Select Channel, Turn-On A/D
' 7=0 Unused
' 6=0 Unused
' 5=0 )
' 4=0 )
' 3=0 ) selects AN1
' 2=0 )
' 1=0 Go-done Bit
' 0=1 switch-On ADC Module
Pauseus 50 ' Wait for channel to setup
ADCON0.1 = 1 ' Start conversion
While ADCON0.1=1:Wend ' Wait for conversion
DataW.HighByte=ADRESH ' Read variable from ADC and save
DataW.LowByte=ADRESL
RawData(CounterA)=DataW
Next CounterA
' Sort ADC Input
' --------------
CounterA=0
GetADCSortLoop:
If RawData(CounterA+1) < RawData(CounterA) then
DataW=RawData(CounterA)
RawData(CounterA)=RawData(CounterA+1)
RawData(CounterA+1)=DataW
If CounterA>0 then CounterA=CounterA-2
endif
CounterA=CounterA+1
If CounterA < 15 then goto GetADCSortLoop
' Quanticise, discarding top and bottom FOUR elements
' ----------------------------------------------------
DataW=0
For CounterA=4 to 11
DataW=DataW+RawData(CounterA)
Next CounterA
ADCInVal=DataW>>3 ' Divide Result by EIGHT
' Read trim pot Vref to set LED brightness
' PAUSEUS 50 ' Wait for A/D channel acquisition time
' ADCON0.1 = 1 ' Start conversion
' WHILE ADCON0.1 = 1 ' Wait for it to complete
' WEND
' ADCInVal.HighBYTE = ADRESH
' ADCInVal.LOWBYTE = ADRESL
return
'*********** Set duty registers ****************************************
ChngLEDBrightness:
CCP1CON.4 = LEDBrVal.0
CCP1CON.5 = LEDBrVal.1
CCPR1L = LEDBrVal >> 2
RETURN
Re: Scaling ADC Result to a Set Range
Bookmarks