1 // Voltage.c, DW Smith, 1st December 2011
2 #include < p18f1220. h >
3 #pragma config WDT = OFF, OSC = INTIO2, PWRT = ON, LVP = OFF, MCLRE = OFF
4 #include < delays.h >
5
6 int READING;
7 float VOLTAGE; // Voltage is a decimal number not an integer.
8
9 void main (void)
10 {
11 // SET UP
12 // OSCCON defaults to 31 kHz. So no need to alter it.
13 ADCON1 = 0x7E; // AN0 is analogue or 0b01111110 in binary
14 TRISA = 0b11111111; // sets PORTA as all inputs, bit0 is AN0
15 PORTA = 0b00000000; // turns off PORTA outputs, not required, no outputs
16 TRISB = 0b00000000; // sets PORTB as all outputs
17 PORTB = 0b00000000; // turns off PORTB outputs,
good start position
18 ADCON0bits.ADON = 1; // turn on A/ D
19 ADCON2 = 0b10000000; // right justified, acquisition times are ok at 0 with 31 kHz
20
21 while (1)
22 {
23 ADCON0bits.GO_DONE = 1; // do A/ D measurement
24 while (ADCON0bits.GO_DONE = = 1); // wait until bit = 0 measurement completed
25 READING = ADRESL +( ADRESH * 256);
26 VOLTAGE = READING/ 204.6;
27
28 if (VOLTAGE > 0 && VOLTAGE < = 1) PORTB = 0b00000000;
29 if (VOLTAGE > 1 && VOLTAGE < = 2) PORTB = 0b00000001;
30 if (VOLTAGE > 2 && VOLTAGE < = 3) PORTB = 0b00000011;
31 if (VOLTAGE > 3 && VOLTAGE < = 4) PORTB = 0b00000111;
32 if (VOLTAGE > 4 && VOLTAGE < =5) PORTB = 0b00001111;
33 }
34 }Brilliant Adam - its of much use thank you!!! It is clearly commented and not obfuscated with many function calls - very low level and simple, easy to follow along. I will see if I can put it to use later on today, thanks again for finding that
/*
* File: devboard.c
*
*
* Created on June 2, 2015, 9:33 PM
*/
// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.
// CONFIG
#pragma config FOSC = INTRCIO // Oscillator Selection bits (INTOSC oscillator: I/O function on GP4/OSC2/CLKOUT pin, I/O function on GP5/OSC1/CLKIN)
#pragma config WDTE = OFF // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF // Power-Up Timer Enable bit (PWRT disabled)
#pragma config MCLRE = ON // GP3/MCLR pin function select (GP3/MCLR pin function is MCLR)
#pragma config BOREN = OFF // Brown-out Detect Enable bit (BOD disabled)
#pragma config CP = OFF // Code Protection bit (Program Memory code protection is disabled)
#pragma config CPD = OFF // Data Code Protection bit (Data memory code protection is disabled)
#include <stdio.h>
#include <stdlib.h>
#include <xc.h>
#define _XTAL_FREQ 4000000
int AD_IN; //variable to hold value of A/D input from potentiometer.
void main (void)
{
// SET UP
ADCON0 = 0b0000101; // AN1 is analogue, turning on analog channel and starting converter
TRISIO = 0b001010; //Only AN1 and AN3/MCLR are inputs all else outputs.
//good start position
ADCON0bits.ADON = 1; // turn on A/D
ANSEL = 0b0110010; //AN1 set to Analog, other 3 pins are digital, 011 on right side indicates FRC for timing
while (1)
{
ADCON0bits.GO_DONE = 1; // do A/ D measurement
while (ADCON0bits.GO_DONE == 1); // wait until bit = 0 measurement completed
{AD_IN = ADRESH; //ADRESL +( ADRESH * 256);
AD_IN = AD_IN/256; //
if ((AD_IN > 0) && (AD_IN <=50)) //compiler ok with this if conditional the next two get flagged with various syntax issues??
{
GPIO = 0b000100;
}
if ((AD_IN > 75) && (AD_IN < = 150))
{
GPIO = 0b010000;
}
if ((AD_IN > 175) && (AD_IN < =255))
{
GPIO = 0b100000;
}
}
}
}if (VOLTAGE > 0 && VOLTAGE < = 1)Thank you North - syntax kills me!!d LOL
No worries mate, it was a good challenge to learn to spot things in code for me too!! The code works and now my dev. board responds appropriately, in this case it compares the range of the potentiometer and when the input is between:
/*
* File: devboard.c
*
* Created on June 2, 2015, 9:33 PM
*/
// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.
// CONFIG
#pragma config FOSC = INTRCIO // Oscillator Selection bits (INTOSC oscillator: I/O function on GP4/OSC2/CLKOUT pin, I/O function on GP5/OSC1/CLKIN)
#pragma config WDTE = OFF // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF // Power-Up Timer Enable bit (PWRT disabled)
#pragma config MCLRE = ON // GP3/MCLR pin function select (GP3/MCLR pin function is MCLR)
#pragma config BOREN = OFF // Brown-out Detect Enable bit (BOD disabled)
#pragma config CP = OFF // Code Protection bit (Program Memory code protection is disabled)
#pragma config CPD = OFF // Data Code Protection bit (Data memory code protection is disabled)
#include <stdio.h>
#include <stdlib.h>
#include <xc.h>
#define _XTAL_FREQ 4000000
int AD_IN; //variable to hold value of A/D input from potentiometer.
void main (void)
{
// SET UP
ADCON0 = 0b0000101; // AN1 is analogue, turning on analog channel and starting converter
TRISIO = 0b001010; //Only AN1 and AN3/MCLR are inputs all else outputs.
while (1)
{
//good start position
//ADCON0bits.ADON = 1; // turn on A/D
ANSEL = 0b0110010; //AN1 set to Analog, other 3 pins are digital, 011 on right side indicates FRC for timing
ADCON0bits.GO_DONE = 1; // do A/ D measurement
while (ADCON0bits.GO_DONE == 1) // wait until bit = 0 measurement completed
{
AD_IN = ADRESH; //ADRESL +( ADRESH * 256); //changed value of 256 to 1024 since this chip is 10 bit
if ((AD_IN) > 0 & (AD_IN <=50))
{
GPIO = 0b000100;
}
if ((AD_IN > 75) && (AD_IN <= 150))
{
GPIO = 0b010000;
}
if ((AD_IN > 175) && (AD_IN <= 255))
{
GPIO = 0b100000;
}
}
}
}
Now that would be a real mess!
I watched it on TV. You guys made the national news. Are you still dry?BTW you're missing one hell of a shower down here
The two bits stored in bit positions 0 and 1 of the 8-bit register ADRESH must represent the two most significant bits of a 10-bit result stored in a 16-bit unsigned integer variable, AD_IN. You need to get those two bits to transfer over to bit positions 8 and 9 in AD_IN.Why are we multiplying ADRESH by 256?
Yep! Lots of rain, but inside all is well
Cool!! Glad it finally got there. Yes, test fit your parts, you never know since I sized this for the parts I had on hand. I am glad I have a working version, its a lot better than breadboarding in the sense that you know that you have a working baseline. Thanks for the compliment on the board, I think it came out pretty spiffy for a home made job, despite the failed solder mask (again) LOL. I am sure once you are settled you will be able to crank out some of your own boards. Especially since I found you that great deal on Amazon for ferric chloride LOL.
I find this strange since when I think of a multiplication operation, that its a decimal event, meaning 3x2=6. In our example, lets say we have 0000 0001 and we multiply by 256 then we have 1000 0000! But its not ten million but the binary representation of 256 which indeed is what 1x256 is. And its even stranger that it's simply a shift to the left like that. I get it, but it takes awhile for the info to take hold, thanks for explaining it and yes, shifting is the way to go!!!
I believe that is what the code Adam posted did, IIRC.
makes sense, you're in a way, typecasting, since we set AD_IN as an unsigned integer. That is a good pickup Hop!!
Re: ICSP failure to program while in circuit? Yesterday
<<
From me:
I don't see how the Schottky diode idea ever worked. Many PICs have an internal pullup for /MCLR, and if the diode is oriented to block current from the /MCLR pin to the reset circuit, it is impossible for the reset circuit to pull /MCLR low against the pullup.
>>
It was my understanding that the MCLR pin has to be held high and when it goes low, then the reset occurs. The schottky in my accompanying schematic does work (physically tested on a working board, resets fine via a tactile switch with a r/c debounce). The diode allows current to pass towards the chip from R2 which is fed by Vdd.
In my example, I am not using the WPUA register.
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Ian.M
Super Member
Re: ICSP failure to program while in circuit? Yesterday
The /MCLR pin is a somewhat modified CMOS input that also has a circuit to detect if its above Vdd enough for VPP to be present. The max /MCLR leakage current at input voltages between the supply rails is +/-5uA and +/-0.1uA is quoted as typical. (parameter D061)
Probably either the diode's reverse leakage current and/or the junction capacitance of the diode was enough to pull /MCLR low momentarily. *NOT* something I would trust to work with *ANY* combination of PIC and small signal Schottky diode.Close, but no cigar! 0000 0001 multiplied by 256 is 1 0000 0000. Or regrouping the digits for base eight, 100 000 000 which I suppose you could read aloud as one hundred million. But nobody I know does that. And base eight notation died a deserved death in the twentieth century.
