 |
 |
| View previous topic :: View next topic |
| Author |
Message |
mizzard
Joined: 26 Apr 2009
Posts: 11
|
| Problems using AD in dspic33EP256MU806 with Vref+ |
 Posted: Fri Nov 16, 2012 4:28 am |
 |
|
Hello everybody,
I am developing a project and I use the dspic33EP256MU806 using CCS PCWHD version 4.128.
The problem is that the AD is working fine but only if I work using AVdd and AVss, and when I try to work using a voltage reference on pin RB0 (Vref+ to AVss), it still working ignoring that change.
NOTE: Avdd = Vdd = 3.3V and Vref+ = 3.0V
To making tests, I use this simplified code:
<main.h>
| Code: | #include <33EP256MU806.h>
//#device adc=10
#FUSES NODEBUG //No Debug mode for ICD
#FUSES PUT128 //Power On Reset Timer value 128ms
#FUSES NOWDT //No Watch Dog Timer
#FUSES PR_PLL
#FUSES HS
#FUSES ICSP1
#FUSES OSCIO
#FUSES CKSFSM
#FUSES NOIOL1WAY //Allows multiple reconfigurations of peripheral pins
// Oscillator
#WORD CLKDIV = 0x0744 //PLLPOST(6,7) - PLLPRE(0,1,2,3,4)
#BIT PLLPOST_0 = CLKDIV.6
#BIT PLLPOST_1 = CLKDIV.7
#BIT PLLPRE_0 = CLKDIV.0
#BIT PLLPRE_1 = CLKDIV.1
#BIT PLLPRE_2 = CLKDIV.2
#BIT PLLPRE_3 = CLKDIV.3
#BIT PLLPRE_4 = CLKDIV.4
#WORD PLLFBD = 0x0746 //PLLDIV(0,1,2,3,4,5,6,7,8)
#BIT PLLDIV_0 = PLLFBD.0
#BIT PLLDIV_1 = PLLFBD.1
#BIT PLLDIV_2 = PLLFBD.2
#BIT PLLDIV_3 = PLLFBD.3
#BIT PLLDIV_4 = PLLFBD.4
#BIT PLLDIV_5 = PLLFBD.5
#BIT PLLDIV_6 = PLLFBD.6
#BIT PLLDIV_7 = PLLFBD.7
#BIT PLLDIV_8 = PLLFBD.8
#WORD OSCCON = 0x0742 // OSWEN(0) - NOSC(8,9,10)
#BIT OSWEN = OSCCON.0
#BIT NOSC_0 = OSCCON.8
#BIT NOSC_1 = OSCCON.9
#BIT NOSC_2 = OSCCON.10
#use delay(crystal=4000000,clock=120000000)
// SOFTWARE SERIAL PORT
#use rs232(stream = DEBUG, xmit=PIN_B7, rcv=PIN_B6, baud=115200, parity=N, bits=8)
// AD CONFIG REGISTERS
// INPUTS AND ANALOG PINS
#byte TRISB = 0x0E10
#bit TRISB0 = TRISB.0
#bit TRISB1 = TRISB.1
#bit TRISB2 = TRISB.2
#byte ANSELB = 0x0E1E
#bit ANSB0 = ANSELB.0
#bit ANSB1 = ANSELB.1
#bit ANSB2 = ANSELB.2
#byte ADC1BUF0 = 0x0300
#byte AD1CON1 = 0x0320
#bit VCFG_2 = AD1CON1.15
#bit VCFG_1 = AD1CON1.14
#bit VCFG_0 = AD1CON1.13
#byte AD1CON2 = 0x0322
#byte AD1CON3 = 0x0324
#byte AD1CON4 = 0x0332
#byte AD1CHS123 = 0x0326
#byte AD1CHS0 = 0x0328
#byte AD1CSSH = 0x032e
#byte AD1CSSL = 0x0330
#bit ADON = AD1CON1.15
#bit SAMP = AD1CON1.1
#bit DONE = AD1CON1.0
|
<main.c>
| Code: | #include <math.h>
#include <stdio.h>
#include <string.h>
const unsigned int READ_SAMPLE_TIMES=20; // us
unsigned int16 leeCanalADC(unsigned int canal);
#INT_TIMER1
void tmr1_Interrupt(void){
set_timer1(15535); // 200 ms
if(cTMR1<10){
cTMR1++;
}
else if(cTMR1>=10){
// Update every AD reading each 2 sec
bActualizarInfo=true;
cTMR1=0;
}
}
void main(){
// Para tratar la respuesta de las funciones
// signed int respuestaFuncion=0;
unsigned int16 lecturaADC = 0;
unsigned int16 valorMedio = 0;
float resultVoltios = 0.0;
unsigned int numMuestras=0;
// Main oscillator XT/HS con PLL -> Fin = 4 MHz
OSWEN = 1;
NOSC_0 = 1;
NOSC_1 = 1;
NOSC_2 = 0;
// PLLPRE=0 Luego N1=2
PLLPRE_0 = 0;
PLLPRE_1 = 0;
PLLPRE_2 = 0;
PLLPRE_3 = 0;
PLLPRE_4 = 0;
// PLLPOST=0 Luego N2=2
PLLPOST_0 = 0;
PLLPOST_1 = 0;
// PLLDIV=118 Luego M=120
PLLDIV_0 = 0;
PLLDIV_1 = 1;
PLLDIV_2 = 1;
PLLDIV_3 = 0;
PLLDIV_4 = 1;
PLLDIV_5 = 1;
PLLDIV_6 = 1;
PLLDIV_7 = 0;
PLLDIV_8 = 0;
delay_ms(500);
// AD CONFIG
TRISB0 =1; // RB0 -> INPUT
ANSB0 = 1; // Analog AN0 -> RB0
TRISB1 =1; // RB1 -> INPUT
ANSB1 = 1; // Analog AN1 -> RB1
/*
TRISB2 =1; // RB2 -> INPUT
ANSB2 = 1; // Analog AN2 -> RB2
*/
AD1CON1=0x0000;
// AD1CON2=0x2000; // The same as the following two lines
/*
VCFG_2=0; // Vref+ - GND
VCFG_1=0;
VCFG_0=1;
*/
AD1CSSL=0x0000; // no scan
AD1CON3=0x8000; // internal;
AD1CHS0= 0x0001; //CHANNEL 1
// TIMERS
setup_timer1(TMR_INTERNAL|TMR_DIV_BY_256);
// TMR_INTERNAL = fuente de reloj interna 16bits
// El timer se incrementa cada:
// 1/120MHz * 2 {ciclo instruc} * 256 {preescaler} = 4,26 useg = aprox 4 useg
// INTERRUPTS
// SERIAL
enable_interrupts(INT_RDA);
enable_interrupts(INT_RDA2);
enable_interrupts(INT_RDA3);
enable_interrupts(INT_RDA4);
// Timer1
set_timer1(15535);
enable_interrupts(INT_TIMER1);
enable_interrupts(INTR_GLOBAL);
delay_ms(3000);
fprintf(DEBUG,"Start\r\n");
while(true){
if (bActualizarInfo){
// CHANNEL 1
lecturaADC = leeCanalADC(1);
// resultVoltios = (3.0/1024.0)*lecturaADC;
fprintf(DEBUG,"\r\nCanal 2: %lu",lecturaADC);
// fprintf(DEBUG,"\r\nCanal 2: %.3f",resultVoltios);
// DEBUG <--------------
bActualizarInfo = false;
}
}
}
unsigned int16 leeCanalADC(unsigned int canal){
unsigned int16 *pADCVal=0;
// AD1CHS0= (0x0000 + (byte)(canal)); // Canal 1 or 2
/*
// PUEDO PONER ESTO EN CONFIG INICIAL DEL CAD ->FUNCION
AD1CSSL=0x0000; // no scan
AD1CON3=0x8000; // internal;
// PUEDO PONER ESTO EN CONFIG INICIAL DEL CAD ->FUNCION
*/
// AD1CON2=0x2000; // Vref+ - GND
delay_us(READ_SAMPLE_TIMES); //some delay
ADON = 1; // ADC ON
SAMP = 1; // start sampling
delay_us(READ_SAMPLE_TIMES); //some delay
SAMP = 0; //stop sampling and start conversion
while(!DONE); //while conversion not done stay here
pADCVal=&ADC1BUF0; //when conversion done save value form buffer to variable.
ADON = 0; // ADC OFF
return (*pADCVal);
}
|
I have read all the AD chapter in the datasheet but I don’t know what to do more. Furthermore I have also tested in other PCB and the result is the same.
Any ideas?
Thank you so much |
|
 |
Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
|
|
| Posted: Fri Nov 16, 2012 5:59 am |
|
|
Might not be the issue but are you sure your running at 120Mhz that the delay_xx will be based on?
You have 4Mhz N1=2 M =120 n2=2 Now doesn't (4/2)*120 =240 take you outside the 200Mhz max restriction of the internals of the PLL. N2=2 would get you back to 120Mhz providing the PIC's VCO can handle 240Mhz internally.
Last edited by Douglas Kennedy on Fri Nov 16, 2012 6:03 am; edited 1 time in total |
|
|
mizzard
Joined: 26 Apr 2009
Posts: 11
|
|
| Posted: Fri Nov 16, 2012 6:01 am |
|
|
| Douglas Kennedy wrote: | Might not be the issue but are you sure your running at 120Mhz that the delay_xx will be based on?
You have 4Mhz N1=2 M =120 n2=2 Now doesn't (4/2)*120 =240take outside the 200Mhz max restriction of the internals of the PLL. |
Yes, because timer1 and fprintf on debug stream work fine
See page 179:
http://ww1.microchip.com/downloads/en/DeviceDoc/70616g.pdf |
|
|
Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
|
|
| Posted: Fri Nov 16, 2012 11:13 am |
|
|
| You're right the EP does go to 60 MIPS....I had some issues with getting a 24HJ to run at 40 mips and guessed your issue might be related. |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
