Pretty New and need help please
Hi Everyone,
I'm using a PIC16F877 chip in this project.
I'm still pretty new at PIC programming and there's alot I don't know or understand!
About 34 or 35 lines below, you will see *** ;ADCON1=%00000011 and ;ADCON1=%00000010 ***
The reason these lines are marked as notes (;) is because I can not get the results I expected!
I'm trying to use A2D Channels 0 and 1. Channel 0's input ranges from 0 to + 5 VDC.
Channel 1's input ranges from 0 to + 1 VDC.
I'm trying to use a very small input from a current shunt (in Millivolts)
100 Millivolts Max, and display this current on the LCD. With the Vref set
at + 1 VDC, I think I should be able to see current changes of 4 Amps.
Is there a minumum Vref voltage? I've looked over the Datasheet but
have not found anything about Vref minimums. Ideally, I would set
Vref at .255 VDC.
**** Is what I'm trying to do even possible?****
****Any help will really be appreciated!****
'************************************************* ***************
'* Name : New_PWM.bas *
'* Author : Roddy Wayne *
'* Notice : Copyright (c) 2008 *
'* : All Rights Reserved *
'* Date : 08/09/2008 *
'* Version : 1.0 *
'* Notes: *
'* *
'* A PWM for running a Hydrogen Generator *
'************************************************* ***************
CLEAR ;always start with clear
DEFINE OSC 4 ;define oscillator speed
DEFINE ADC_BITS 8 ; Sets number of bits in result
DEFINE ADC_CLOCK 3 ; Sets clock source (3=rc)
DEFINE ADC_SAMPLEUS 50 ; Sets sampling time in uS
define DEBUG_REG PORTC
DEFINE DEBUG_BIT 6
define DEBUG_BAUD 2400
DEFINE DEBUG_MODE 0
DEFINE DEBUG_PACING 1000
Low PORTE.2 ;makes low for write only
TRISA = %00001111 ;sets 0, 1, 2, and 3 as porta inputs (A to D's & ref's)
TRISB = %00111111 ;sets bits 6 & 7 portb pins as outputs, 0 thru 5 as inputs
TRISC = %10111111 ;sets port c.6 for serial output
TRISD = %00000011 ;sets PORTD 0,1, lines to inputs, rest to outputs
TRISE = %00000000 ;sets all PORTE lines to outputs
potpos var BYTE ;potpos is 8 bit
cellamps VAR BYTE ;cellamps is 8 bit
A2D_V VAR BYTE ;Created A2D_V Value to store result
A2D_V2 Var BYTE ;Created A2D_V2 Value to store result
;ADCON1=%00000011 ;Sets the Analog to Digital control register to 4 Channels
;with Vref+ and Ground as the references!
;This Vref is + 1 VDC
;ADCON1=%00000010 ;Sets the Analog to Digital control register to 5 Channels
;with +5 VDC and Ground as the references!
Start:
If portc.0 = 0 then portb.6 = 0 'If pin 15 is low, make pin 39 low
If Portc.0 = 1 then portb.6 = 1 'If pin 15 is high, make pin 39 high
'When Pin 39 goes high, this turns the
'pump on! I'm using a Darlington pair
'to do this (Part # TIP120) It also turns
'on the "Pump On" LED.
If portc.3 = 0 then portb.7 = 0 'If pin 18 is low, make pin 40 low
If portc.3 = 1 then portb.7 = 1 'If pin 18 is high, make pin 40 high
'When Pin 40 goes high, the "Low Tank
'Water" LED is turned on!
ADCON1=%00000010 '?? Setup to read analog inputs
ADCIN 0, A2D_V 'Read channel 0 to A2D_Value
Pause 50
potpos= A2D_V
Debug 14, 1, "Pot Position =", 32, DEC2 potpos, 13
Pause 50
;ADCON1=%00000011
Pause 50
ADCIN 1, A2D_V2 'Read channel 1 to A2D_V2 Value
cellamps= A2D_V2
Debug "Cell Amps =", 32, DEC2 cellamps, 13
Pause 50
HPWM 2, 127, 17500 'Output is a 17.5 Khz, 50% duty cycle (pin 16)
;ADCON1=%0000010
Pause 100
ADCIN 0, A2D_V ' Read channel 0 to A2D_Value
potpos= A2D_V
If (potpos <=%00011100)and(potpos <=%00111111) then percent_40
ADCIN 0, A2D_V ' Read channel 0 to A2D_Value
potpos= A2D_V
If (potpos <=%01000000)and(potpos <=%01011001) then percent_60
ADCIN 0, A2D_V ' Read channel 0 to A2D_Value
potpos= A2D_V
If (potpos <=%01011010)and(potpos <=%01110011) then percent_80
ADCIN 0, A2D_V ' Read channel 0 to A2D_Value
potpos= A2D_V
If (potpos <=%01110100)and(potpos <=%01111110) then percent_100
If (potpos >=%01011110) Then percent_100
'This assures that any potpos >= 11110110, will keep the output
'at 100%, where it used to go back to 50%!!!
percent_40: 'Asking for 40% On / 60% Off
HPWM 1, 102, 17500 'Output is a 17.5 Khz, 40% duty cycle (pin 17)
HPWM 2, 127, 17500 'Output is a 17.5 Khz, 50% duty cycle (pin 16)
Pause 100
DEBUG "PWM = 40%High/60%Low", 32, 32, 1
Pause 400
GoTO start
percent_60: 'Asking for 60% On / 40% Off
HPWM 1, 153, 17500 'Output is a 17.5 Khz, 60% duty cycle (pin 17)
HPWM 2, 127, 17500 'Output is a 17.5 Khz, 50% duty cycle (pin 16)
Pause 100
DEBUG "PWM = 60%High/40%Low", 32, 32, 1
Pause 400
GoTO start
percent_80: 'Asking for 80% On / 20% Off
HPWM 1, 204, 17500 'Output is a 17.5 Khz, 80% duty cycle (pin 17)
HPWM 2, 127, 17500 'Output is a 17.5 Khz, 50% duty cycle (pin 16)
Pause 100
DEBUG "PWM = 80%High/20%Low", 32, 32, 1
Pause 400
GoTO start
percent_100: 'Asking for 99% On / 1% Off
HPWM 1, 253, 17500 'Output is a 17.5 Khz, 100% duty cycle (pin 17)
HPWM 2, 127, 17500 'Output is a 17.5 Khz, 50% duty cycle (pin 16)
Pause 100
DEBUG "PWM = 99%High/01%Low", 32, 32, 1
Pause 400
GoTO start
End
