The Vdd that resistors are connected to, is the exact same point that PIC Vdd pin is connected also?
Ioannis
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Re: How can I reduce ADC drift
The Vdd that resistors are connected to, is the exact same point that PIC Vdd pin is connected also?
Ioannis
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Re: How can I reduce ADC drift
Originally Posted by Ioannis
Yes, it is.
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
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Re: How can I reduce ADC drift
Temperature (heating or cooling PIC) has any effect on the drift?
Ioannis
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Re: How can I reduce ADC drift
I'm curious how can this help me?
It is room temperature, just like target customer environment (gaming).
It's not like I'm overclocking the PIC like a PC CPU...?
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
|
Re: How can I reduce ADC drift
If the ADC result has no or minimal effect because of temp then we have to look elsewhere for the drift.
Ioannis
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Re: How can I reduce ADC drift
I would try the following:
1/. Use the Fixed Voltage Reference (FVR) instead of Vdd as your ADC reference voltage.
2/. Add some capacitance - say 100nF - between the pot wiper and ground.
Cheers
Barry
VK2XBP
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Re: How can I reduce ADC drift
1. Yeah, FVR is on my TO-DO list (Richard mentioned it up there).
2. Does it matter if the cap is at the switch or up against PIC (like decoupler caps).
3. Temp is also on my TO-DO list.
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
|
Re: How can I reduce ADC drift
Ok, finally got back to working on my ADC jitters:
- FOSC/128, 111111, 4.0 uS at 32 MHz
- using FVR x 4
- added 0.1uF at ADC pin
No change, still jitters. I took at the manual averaging routine; it doesn't go to the extreme ends (rarely get completely to 0 or 1024 because of jittter).
I'd like to try one of those COMPUTATION FEATURES, but I'm not sure which is better for me, nor what I need to properly set in the registers:
- Basic: essentially what I'm doing now.
- Accumulate,
- Average,
- Burst Average,
- Low-Pass Filter.
I'm testing 2 pots on this board; 1 regular, 1 with switch.
Code:#CONFIG __config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_OFF & _FCMEN_ON __config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON & _DEBUG_OFF __config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_OFF & _WDTCWS_WDTCWS_7 & _WDTCCS_LFINTOSC __config _CONFIG4, _WRT_OFF & _SCANE_available & _LVP_OFF __config _CONFIG5, _CP_OFF & _CPD_OFF #ENDCONFIG DEFINE OSC 32 DEFINE ADC_BITS 10 ' 10-bit Analog to digital DEFINE LCD_DREG PORTB ' Set LCD data port DEFINE LCD_DBIT 0 ' Set starting data bit DEFINE LCD_RSREG PORTC ' Set LCD register select port DEFINE LCD_RSBIT 4 ' Set LCD register select bit DEFINE LCD_EREG PORTC ' Set LCD enable port DEFINE LCD_EBIT 5 ' Set LCD enable bit DEFINE LCD_BITS 4 ' Set LCD bus size DEFINE LCD_LINES 4 ' Set number of lines on LCD DEFINE LCD_COMMANDUS 1000 ' Set command delay time in microseconds DEFINE LCD_DATAUS 50 ' Set data delay time in microseconds define CCP1_REG 0 ' Must clear unused CCP pins or else unpredictable results DEFINE CCP1_BIT 0 define CCP2_REG 0 DEFINE CCP2_BIT 0 define CCP3_REG PORTB ' PWM Pulse out to LCD backlight DEFINE CCP3_BIT 5 define CCP4_REG 0 ' Must clear unused CCP pins or else unpredictable results DEFINE CCP4_BIT 0 define CCP5_REG 0 DEFINE CCP5_BIT 0 FVRCON = %10000011 ' FIXED VOLTAGE REFERENCE CONTROL REGISTER ' bit 7 FVREN: Fixed Voltage Reference Enable bit ' ---> 1 = Fixed Voltage Reference is enabled ' 0 = Fixed Voltage Reference is disabled ' bit 6 FVRRDY: Fixed Voltage Reference Ready Flag bit(1) ' 1 = Fixed Voltage Reference output is ready for use ' 0 = Fixed Voltage Reference output is not ready or not enabled ' bit 5 TSEN: Temperature Indicator Enable bit(3) ' 1 = Temperature Indicator is enabled ' 0 = Temperature Indicator is disabled ' bit 4 TSRNG: Temperature Indicator Range Selection bit(3) ' 1 = VOUT = VDD - 4VT (High Range) ' 0 = VOUT = VDD - 2VT (Low Range) ' bit 3-2 CDAFVR<1:0>: Comparator FVR Buffer Gain Selection bits ' 11 = Comparator FVR Buffer Gain is 4x, (4.096V)(2) ' 10 = Comparator FVR Buffer Gain is 2x, (2.048V)(2) ' 01 = Comparator FVR Buffer Gain is 1x, (1.024V) ' 00 = Comparator FVR Buffer is off ' bit 1-0 ADFVR<1:0>: ADC FVR Buffer Gain Selection bit ' ---> 11 = ADC FVR Buffer Gain is 4x, (4.096V)(2) ' 10 = ADC FVR Buffer Gain is 2x, (2.048V)(2) ' 01 = ADC FVR Buffer Gain is 1x, (1.024V) ' 00 = ADC FVR Buffer is off ' ' Note 1: FVRRDY is always ‘1’ for PIC16F18855/75 devices only. ' 2: Fixed Voltage Reference output cannot exceed VDD. CCP3CON = %10001111 ' CCP3 CONTROL REGISTER ' bit 7 EN: CCPx Module Enable bit ' 1 = CCPx is enabled ' 0 = CCPx is disabled ' bit 6 Unimplemented: Read as ‘0’ ' bit 5 OUT: CCP3 Output Data bit (read-only) ' bit 4 FMT: CCPW (Pulse Width) Alignment bit ' MODE = Capture mode ' Unused ' MODE = Compare mode ' Unused ' MODE = PWM mode ' 1 = Left-aligned format ' 0 = Right-aligned format ' bit 3-0 MODE<3:0>: CCPx Mode Select bits(1) ' ---> 1111 = PWM mode ' 1110 = Reserved ' 1101 = Reserved ' 1100 = Reserved ' 1011 = Compare mode: output will pulse 0-1-0; Clears TMR1 ' 1010 = Compare mode: output will pulse 0-1-0 ' 1001 = Compare mode: clear output on compare match ' 1000 = Compare mode: set output on compare match ' 0111 = Capture mode: every 16th rising edge of CCPx input ' 0110 = Capture mode: every 4th rising edge of CCPx input ' 0101 = Capture mode: every rising edge of CCPx input ' 0100 = Capture mode: every falling edge of CCPx input ' 0011 = Capture mode: every edge of CCPx input ' 0010 = Compare mode: toggle output on match ' 0001 = Compare mode: toggle output on match; clear TMR1 ' 0000 = Capture/Compare/PWM off (resets CCPx module) ADCON0 = %10000100 ' ADC CONTROL REGISTER 0 ' bit 7 ADON: ADC Enable bit ' ---> 1 = ADC is enabled ' 0 = ADC is disabled ' bit 6 ADCONT: ADC Continuous Operation Enable bit ' 1 = ADGO is retriggered upon completion of each conversion trigger until ADTIF is set (if ADSOI is ' set) or until ADGO is cleared (regardless of the value of ADSOI) ' ---> 0 = ADGO is cleared upon completion of each conversion trigger ' bit 5 Unimplemented: Read as ‘0’ ' bit 4 ADCS: ADC Clock Selection bit ' 1 = Clock supplied from FRC dedicated oscillator ' ---> 0 = Clock supplied by FOSC, divided according to ADCLK register ' bit 3 Unimplemented: Read as ‘0’ ' bit 2 ADFRM0: ADC results Format/alignment Selection ' ---> 1 = ADRES and ADPREV data are right-justified ' 0 = ADRES and ADPREV data are left-justified, zero-filled ' bit 1 Unimplemented: Read as ‘0’ ' bit 0 ADGO: ADC Conversion Status bit ' 1 = ADC conversion cycle in progress. Setting this bit starts an ADC conversion cycle. The bit is ' cleared by hardware as determined by the ADCONT bit ' ---> 0 = ADC conversion completed/not in progress ADCLK = %00111111 ' ADC CLOCK SELECTION REGISTER ' bit 7-6 Unimplemented: Read as ‘0’ ' bit 5-0 ADCCS<5:0>: ADC Conversion Clock Select bits ' ---> 111111 = FOSC/128 ' 111110 = FOSC/126 ' 111101 = FOSC/124 ' • ' 000000 = FOSC/2 ADPCH = %00000000 ' ADC POSITIVE CHANNEL SELECTION REGISTER ' bit 7-6 Unimplemented: Read as ‘0’ ' bit 5-0 ADPCH<5:0>: ADC Positive Input Channel Selection bits ' 111111 = Fixed Voltage Reference (FVR) ' 111110 = DAC1 output ' 111101 = Temperature Indicator ' 111100 = AVSS (Analog Ground) ' 111011 = Reserved. No channel connected. ' • ' • ' • ' 100010 = ANE2 * 16F18877 only ' 100001 = ANE1 * 16F18877 only ' 100000 = ANE0 * 16F18877 only ' 011111 = AND7 * 16F18877 only ' 011110 = AND6 * 16F18877 only ' 011101 = AND5 * 16F18877 only ' 011100 = AND4 * 16F18877 only ' 011011 = AND3 * 16F18877 only ' 011010 = AND2 * 16F18877 only ' 011001 = AND1 * 16F18877 only ' 011000 = AND0 * 16F18877 only ' 010111 = ANC7 ' 010110 = ANC6 ' 010101 = ANC5 ' 010100 = ANC4 ' 010011 = ANC3 ' 010010 = ANC2 ' 010001 = ANC1 ' 010000 = ANC0 ' 001111 = ANB7 ' 001110 = ANB6 ' 001101 = ANB5 ' 001100 = ANB4 ' 001011 = ANB3 ' 001010 = ANB2 ' 001001 = ANB1 ' 001000 = ANB0 ' 000111 = ANA7 ' 000110 = ANA6 ' 000101 = ANA5 ' 000100 = ANA4 ' 000011 = ANA3 ' 000010 = ANA2 ' ---> 000001 = ANA1 ' ---> 000000 = ANA0 ANSELA = %00000011 ' Pin A1 = ADC ' Pin A0 = ADC ANSELB = %00000000 ANSELC = %00000000 TRISA = %00000111 ' Pin A2 = SW input 1 ' Pin A1 = ADC input 1 ' Pin A0 = ADC input 0 TRISB = %00000000 TRISC = %00000000 SW1 var PORTA.2 ADCinput var WORD OldADC0 var WORD OldADC1 var WORD OldSW1 var BYTE NewADC0 var WORD NewADC1 var WORD HPWMbacklight var BYTE ' Pause 200 ' Let PIC and LCD stabilize ADCinput = 0 OldADC0 = 9999 OldADC1 = 9999 OldSW1 = 9 NewADC0 = 0 NewADC1 = 0 HPWMbacklight = 150 HPWM 3,HPWMbacklight,1953 LCDOUT $FE, 1 : Pauseus 1 LCDOUT $FE, $80, " ADC test" : Pauseus 1 LCDOUT $FE, $94, "ADC 0:" : Pauseus 1 LCDOUT $FE, $D4, "ADC 1: SW:" : Pauseus 1 Mainloop: rem ADC 0 ADPCH = %00000000 adcin 0, ADCinput NewADC0 = 1023 - ADCinput if NewADC0 <> oldadc0 then oldadc0 = NewADC0 LCDOUT $FE, $94+7, DEC4 oldadc0 : Pauseus 1 endif rem ADC 1 ADPCH = %00000001 adcin 1, ADCinput NewADC1 = 1023 - ADCinput if NewADC1 <> oldadc1 then oldadc1 = NewADC1 LCDOUT $FE, $D4+7, DEC4 oldadc1 : Pauseus 1 endif rem SW 1 if SW1 <> oldSW1 then oldSW1 = SW1 IF OldSW1 = 0 THEN LCDOUT $FE, $D4+17, "Off" : Pauseus 1 else LCDOUT $FE, $D4+17, "On " : Pauseus 1 endif endif HPWMbacklight = 255 - (NewADC0 / 4) HPWM 3,HPWMbacklight,1953 GOTO Mainloop end
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
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