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davey
Joined: 04 May 2006
Posts: 17
Location: Sweden
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| Can�t get 20MHz crystal to work!!! |
 Posted: Mon May 29, 2006 9:34 am |
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Hi there!
I trying to connect a 20 MHz crystal (http://www.elfa.se/elfa-bin/dyndok.pl?lang=se&vat=0&dok=2013473.htm) to a PIC16F877A-processor, but I can�t get it to start. Both the processor and the crystal are stone-dead. Each pin of the crystal is connected to ground via a 22pF-cap and to pin 13 & 14 of the PIC. I�ve also tried changing to 33pF-caps, but it doesn�t help...
What could be wrong? 
Cheers!
/David |
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rwyoung
Joined: 12 Nov 2003
Posts: 563
Location: Lawrence, KS USA
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| Posted: Mon May 29, 2006 10:17 am |
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1) Are you certain you have a parallel resonant crystal? The page you reference shows you can order either a parallel or series crystal.
2) Are you using the HS fuse?
3) You don't describe your construction method. Breadboard (white, push in wire kind)? Point-to-pont? PCB? etc.
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month! |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Mon May 29, 2006 10:23 am |
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I have some questions:
1) Are you sure that the PIC you are using is capable to run at 20Mhz ?
2) What about the Reset pin voltage ?
3) What about the Configuration Fuses ?
4) Can you change one of them ? (PIC or crystal)
Humberto |
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Ttelmah
Guest
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| Posted: Mon May 29, 2006 10:30 am |
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You don't say whether you have the first crystal or the second. Both should oscillate, but the first is the one designed to run in the normal PIC oscillator configuration.
Obvious first thing, have you got HS mode selected in the fuses?. If not there will probably not be enought drive to run the crystal.
Second thing is to look at the other connections round the chip. For example, the oscillator will not start, if MCLR is not held high.
Third thing is, have you tried more than one chip/crystal. Anything can be faulty.
Best Wishes |
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davey
Joined: 04 May 2006
Posts: 17
Location: Sweden
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| ... |
| Posted: Mon May 29, 2006 10:34 am |
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Yes I have a parallel resonant crystal.
I tried setting the HS-fuse but it doesn�t help.
All components are placed on a contact-deck and connected to each other with cables.
The PIC is capable of running a 20MHz.
The reset-pin is connected to 5V - ok
I can change the fuses. Here�s my current pre-processor commands:
| Code: |
#fuses NOWDT
#use delay(clock=20000000) |
Any other suggestions...please?
/David |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Mon May 29, 2006 10:39 am |
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| Quote: |
Any other suggestions...please?
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#fuses HS,NOWDT,NOPROTECT,NOLVP,PUT
Humberto |
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davey
Joined: 04 May 2006
Posts: 17
Location: Sweden
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| ...ok, but I�ve already tried setting the HS-fuse... |
| Posted: Mon May 29, 2006 11:02 am |
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...and it doesn�t make any difference.
Please continue to share your thoughts!
Cheers!
/David |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Mon May 29, 2006 11:52 am |
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So that this does not seem a game of successes and errors, please post:
1) The complete code you are using to test.
2) A complete hardware description.
3) Compiler version.
Humberto |
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davey
Joined: 04 May 2006
Posts: 17
Location: Sweden
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| ok...here it goes... |
| Posted: Mon May 29, 2006 12:35 pm |
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HARDWARE:
Nothing special, just a PIC16F877A with four (five with reset) user-buttons attached to B0,B1,B2 & B4. I also have an i2c-connection with another PIC...but that shouldn�t have anything to do with my problem.
Earlier, I�ve connected the osc-inputs on my PIC to the oscillator on a development-board (microEngineering Labs - LAB-X1). And that works perfectly. That oscillator is connected to a multiplier and is sort of running by itself, so that�s a bit different I guess...
CODE:
| Code: | #include <puls.H>
#include <math.h>
#fuses HS,NOWDT
#use i2c(slave,sda=PIN_C4,scl=PIN_C3,address=0x6C,force_hw)
int16 freq=20; //aktuell frekvens f�r denna slav
int16 freq_tmp=20;
byte tmp3; //anv av timer1_isr()
byte received; //mottagen byte via i2c
typedef enum {FIRST_READ, LAST_READ} I2C_STATE;
I2C_STATE i2c_status=FIRST_READ; //anv f�r att skilja p� mottagen adress/data
//Timer 1
int16 t1sv=3160; //Start-v�rde (65535-3160=62375) f�r Timer1 (ger 20Hz)
int16 t1svmod;
int16 temp;
//(((((((((((((((((((((((( INTERRUPTS ))))))))))))))))))))))))))))
#int_timer1 //KANAL 1
timer1_isr()
{
tmp3=TIMER1_CTRL;
TIMER1_CTRL=0x00;
t1svmod=t1sv;
TIMER_1_LOW=t1svmod&0x00FF; //laddar med den f�rsta byten av t1sv
t1svmod >>= 8; //shiftar 8 bitar till h�ger
TIMER_1_HIGH=t1svmod&0x00FF;//laddar med den andra byten av t1sv
port_c ^= 1; //0->1 el. 1->0
TIMER1_CTRL=tmp3;
}
#int_ssp
receive_isr()
{
//ladda freq med mottaget v�rde
if(i2c_poll())
{
if(!bit_test(i2c_stat,5))
{
//ta hand om adress-byte
received=i2c_read();
}
else if(i2c_status==FIRST_READ && bit_test(i2c_stat,5))
{
//ta hand om f�rsta data-byten
received=i2c_read();
freq_tmp=received;
i2c_status=LAST_READ;
}
else if(i2c_status==LAST_READ && bit_test(i2c_stat,5))
{
//ta hand om andra data-byten, sl� samman med f�rsta f�r �nskad freq
received=i2c_read();
freq_tmp=(freq_tmp<<8)&0xFF00;
freq_tmp=freq_tmp+received;
i2c_status=FIRST_READ;
//r�kna ut start-v�rde f�r timer1
freq=freq_tmp;
if(freq>40) TIMER1_CTRL=0x01;
else TIMER1_CTRL=0x11;
temp=2*freq;
if(TIMER1_CTRL==0x11) temp=2495000/temp;
else temp=4990000/temp;
t1sv=65535-temp;
}
}
}
//������������������������������������������������������������������������������
//������������������������������������ MAIN ������������������������������������
//������������������������������������������������������������������������������
main()
{
setup_counters(RTCC_INTERNAL,RTCC_DIV_2);
setup_port_a(NO_ANALOGS);
setup_adc(ADC_CLOCK_INTERNAL);
setup_psp(PSP_DISABLED);
setup_ccp1(CCP_OFF);
setup_ccp2(CCP_OFF);
//====================== I/O ============================
set_tris_d(0x00); // PORT-D: alla utg�ngar
set_tris_c(0xFE); // PORT-C: alla ing�ngar, utom C0(puls-ut)
//=======================================================
//================== SETUP - Timer1 =====================
enable_interrupts(INT_TIMER1);
enable_interrupts(GLOBAL);
TIMER1_CTRL=0x11;
//=======================================================
//========================I2C============================
enable_interrupts(INT_SSP); //s�tter ig�ng i2c-avbrott
//=======================================================
while(1)
{
if(bit_test(i2c_ctrl2,6)) //nollst�lla SSPOV-biten (overflow)
{
bit_clear(i2c_ctrl2,6);
i2c_read();
}
}
}
//������������������������������������������������������������������������������
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H-file
| Code: | #device PIC16F877
#use delay(clock=20000000)
#nolist
/////////////////////////////// I/O definitions for INPUT() and OUTPUT_xxx()
#define PIN_A0 40
#define PIN_A1 41
#define PIN_A2 42
#define PIN_A3 43
#define PIN_A4 44
#define PIN_A5 45
#use fixed_io(A_OUTPUTS=)
#byte port_A=5
#define PIN_B0 48
#define PIN_B1 49
#define PIN_B2 50
#define PIN_B3 51
#define PIN_B4 52
#define PIN_B5 53
#define PIN_B6 54
#define PIN_B7 55
#use fixed_io(B_OUTPUTS=)
#byte port_B=6
#define PIN_C0 56
#define PIN_C1 57
#define PIN_C2 58
#define PIN_C3 59
#define PIN_C4 60
#define PIN_C5 61
#define PIN_C6 62
#define PIN_C7 63
#use fixed_io(C_OUTPUTS=PIN_C6)
#byte port_C=7
#define PIN_D0 64
#define PIN_D1 65
#define PIN_D2 66
#define PIN_D3 67
#define PIN_D4 68
#define PIN_D5 69
#define PIN_D6 70
#define PIN_D7 71
#use fixed_io(D_OUTPUTS=)
#byte port_D=8
#define PIN_E0 72
#define PIN_E1 73
#define PIN_E2 74
#use fixed_io(E_OUTPUTS=)
#byte port_E=9
/////////////////////////////// Useful defines
#define FALSE 0
#define TRUE 1
#define BYTE int
#define BOOLEAN short int
#define getc getch
#define getchar getch
#define puts(s) {printf(s); putchar(13); putchar(10);}
#define putc putchar
/////////////////////////////// Constants used for RESTART_CAUSE()
#define WDT_FROM_SLEEP 0
#define WDT_TIMEOUT 8
#define MCLR_FROM_SLEEP 16
#define NORMAL_POWER_UP 24
/////////////////////////////// Constants used for SETUP_COUNTERS()
#define RTCC_INTERNAL 0
#define RTCC_EXT_L_TO_H 32
#define RTCC_EXT_H_TO_L 48
#define RTCC_DIV_2 0
#define RTCC_DIV_4 1
#define RTCC_DIV_8 2
#define RTCC_DIV_16 3
#define RTCC_DIV_32 4
#define RTCC_DIV_64 5
#define RTCC_DIV_128 6
#define RTCC_DIV_256 7
#define WDT_18MS 8
#define WDT_36MS 9
#define WDT_72MS 10
#define WDT_144MS 11
#define WDT_288MS 12
#define WDT_576MS 13
#define WDT_1152MS 14
#define WDT_2304MS 15
#define L_TO_H 0x40
#define H_TO_L 0
#define RTCC_ZERO 0x0B20 // Used for ENABLE/DISABLE INTERRUPTS
#define RB_CHANGE 0x0B08 // Used for ENABLE/DISABLE INTERRUPTS
#define EXT_INT 0x0B10 // Used for ENABLE/DISABLE INTERRUPTS
#define GLOBAL 0x0BC0 // Used for ENABLE/DISABLE INTERRUPTS
///////////////////////////////////// Constants used for Timer1 and Timer2
#define T1_DISABLED 0
#define T1_INTERNAL 5
#define T1_EXTERNAL 7
#define T1_EXTERNAL_SYNC 3
#define T1_CLK_OUT 8
#define T1_DIV_BY_1 0
#define T1_DIV_BY_2 0x10
#define T1_DIV_BY_4 0x20
#define T1_DIV_BY_8 0x30
#byte TIMER_1_LOW= 0x0e
#byte TIMER_1_HIGH= 0x0f
#byte TIMER1_CTRL= 0x10
#define T2_DISABLED 0
#define T2_DIV_BY_1 4
#define T2_DIV_BY_4 5
#define T2_DIV_BY_16 6
#byte TIMER_2= 0x11
#byte TIMER2_CTRL= 0x12
#byte TIMER2_PERIOD= 0x92
#byte TIMER0_OPT= 0x81
#byte TIMER0_CTRL= 0x8B
#byte TIMER_0= 0x01
#define INT_TIMER1 0x8C01 // Used for ENABLE/DISABLE INTERRUPTS
#define INT_TIMER2 0x8C02 // Used for ENABLE/DISABLE INTERRUPTS
#define INT_TIMER0 0x8B20 // Used for ENABLE/DISABLE INTERRUPTS
//////////////////////////////////// Constants used for SETUP_CCP1()
#define CCP_OFF 0
#define CCP_CAPTURE_FE 4
#define CCP_CAPTURE_RE 5
#define CCP_CAPTURE_DIV_4 6
#define CCP_CAPTURE_DIV_16 7
#define CCP_COMPARE_SET_ON_MATCH 8
#define CCP_COMPARE_CLR_ON_MATCH 9
#define CCP_COMPARE_INT 0xA
#define CCP_COMPARE_RESET_TIMER 0xB
#define CCP_PWM 0xC
#define CCP_PWM_PLUS_1 0x1c
#define CCP_PWM_PLUS_2 0x2c
#define CCP_PWM_PLUS_3 0x3c
#byte CCP_1_LOW= 0x15
#byte CCP_1_HIGH= 0x16
#byte CCP_1_CTRL= 0x17
#define INT_CCP1 0x8C04 // Used for ENABLE/DISABLE INTERRUPTS
//////////////////////////////////// Constants used for SETUP_CCP2()
#byte CCP_2_LOW= 0x1B
#byte CCP_2_HIGH= 0x1C
#define INT_CCP2 0x8D01 // Used for ENABLE/DISABLE INTERRUPTS
//////////////////////////////////// Constants used for SETUP_PSP()
#define PSP_ENABLED 0x10
#define PSP_DISABLED 0
#byte PSP_DATA= 8
#define INT_PSP 0x8C80 // Used for ENABLE/DISABLE INTERRUPTS
//////////////////////////////////// Constants used in SETUP_SSP()
#define SPI_MASTER 0x20
#define SPI_SLAVE 0x24
#define SPI_L_TO_H 0
#define SPI_H_TO_L 0x10
#define SPI_CLK_DIV_4 0
#define SPI_CLK_DIV_16 1
#define SPI_CLK_DIV_64 2
#define SPI_CLK_T2 3
#define SPI_SS_DISABLED 1
#define INT_SSP 0x8C08 // Used for ENABLE/DISABLE INTERRUPTS
#byte i2c_buff= 0x13
#byte i2c_stat= 0x94
#byte i2c_ctrl= 0x0C
#byte i2c_ctrl2= 0x14
#define INT_RDA 0x8C20 // Used for ENABLE/DISABLE INTERRUPTS
#define INT_TBE 0x8C10 // Used for ENABLE/DISABLE INTERRUPTS
///////////////////////////////////// Constants used for SETUP_ADC()
#define ALL_ANALOG 0
#define ANALOG_RA3_REF 1
#define A_ANALOG 2
#define A_ANALOG_RA3_REF 3
#define RA0_RA1_RA3_ANALOG 4
#define RA0_RA1_ANALOG_RA3_REF 5
#define NO_ANALOGS 6
#define ADC_OFF 0
#define ADC_CLOCK_DIV_2 1
#define ADC_CLOCK_DIV_8 0x41
#define ADC_CLOCK_DIV_32 0x81
#define ADC_CLOCK_INTERNAL 0xc1
#define ADC_DONE 0x8C40 // Used for ENABLE/DISABLE INTERRUPTS
////////////////////////////////////////////////////////////////////////////
#byte CONFIG= 0x2007
#list
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COMPILER-VERSION: IDE 3.43/PCB-PCM-PCH 3.203 |
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Ttelmah
Guest
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| Posted: Mon May 29, 2006 2:09 pm |
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Realistically, the most likely thing now, is a faulty crystal. It is suprisingly easy to damage a crystal when soldering, and the only real way to prove this, would be to either put it into a known working oscillator circuit, or use a scope to inspect how it behaves with a signal applied.
Best Wishes |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Mon May 29, 2006 3:59 pm |
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The earlier 3.20x compiler versions was quite buggy. The stable version on those days
was 3.190/91. If you can�t get it, you should try to update it.
http://www.ccsinfo.com/forum/viewtopic.php?t=23792&highlight=203
http://www.ccsinfo.com/forum/viewtopic.php?t=19380&highlight=203
When everything is wrong, the most suitable and recommendable solution is to reduce everything
(hardware and software) to its minimum expression.
| Code: |
#include <18F877A.h>
#use delay(clock=20000000)
#FUSES HS,NOWDT,NOPROTECT,NOLVP,NOPUT, NOBROWNOUT
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
void main()
{
while(1)
{
output_low(PIN_B2);
delay_ms(500);
output_high(PIN_B2);
delay_ms(500);
}
}
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Compile and post your lst file.
Humberto |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 29, 2006 4:05 pm |
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Your program is too complicated to test the crystal problem.
Test it with a very simple program, as shown below. It looks
like you have a spare pin on Pin B5, so I've made the program
toggle that pin. Use this program exactly as shown. Don't
edit the fuses.
Humberto gave you a very good clue when he showed the NOLVP fuse.
You did a test, but you edited out the NOLVP fuse and only tested the
HS fuse. NOLVP is essential for reliable operation with the 16F877A.
| Code: |
#include <16F877A.H>
#fuses HS, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=20000000)
//===================================
void main()
{
while(1)
{
output_high(PIN_B5);
delay_ms(500);
output_low(PIN_B5);
delay_ms(500);
}
} |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Mon May 29, 2006 4:14 pm |
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You are including the header file of the 16F877 instead of the 16F877A.
What values have the capacitors on your clock crystal? The crystal you mentioned has a capacitance of 30pF and requires 2 x 56pF capacitors ( capacitors in parallel = 56x56/(56+56) = 31pF)
99% of the people on this forum need to set the NOLVP fuse as well or the processor will stall when this pin is floating to an active level. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 29, 2006 4:55 pm |
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I don't know if he gave a part number for the crystal, but a typical
20 MHz crystal in an HC-49/US package will be specified to have a
a load capacitance of 18 or 20 pf. See this chart from Digikey:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=163185&Row=682118&Site=US
Here's an appnote on parallel oscillator circuits.
http://www.icst.com/appnotes/note14.PDF
They have a chart on page 2, where they show the load capacitor values,
based upon the specified crystal load capacitance. This appnote takes
into account the internal stray capacitance of the chip's oscillator
circuit, which is something I haven't seen in other appnotes. So for a
crystal spec'ed with an 18 pf load, they recommend external caps of
25 pf. The commonly available values of 22 or 27 pf would work. |
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