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Electronguru
Joined: 26 May 2013
Posts: 11
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| PIC18f4523 code |
 Posted: Mon May 27, 2013 12:03 am |
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Hi ,
I am trying to run this code on 18F4523 , but can't seem to get anything out of it. It programs correctly using PICkit2. I don't get any clock output on pin RA6, or pin 25 (TX), or pin 18 which is SCL output ??? I am trying to use internal oscillator, since there is not external oscillator connected.
Here's the code:
| Code: |
#include <18F4523.h> // PICF4523 header file
#device ADC=12 // 12 bits ADC
#use delay(clock=4000000) // for 4Mhz crystal
#fuses NOWDT, NOPROTECT, NOLVP // for debug mode
#FUSES INTRC //Internal Osc
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, Parity=N, Bits=8, ERRORS)
#use i2c(Master, sda=PIN_C4, scl=PIN_C3)
int d;
void main()
{
int8 data[8] = {0x1A,0x1B,0x2C,0x3D,0x4E,0x5F};
i2c_start();
i2c_write(0xA1);
i2c_write(0xA2);
i2c_write(0xB1);
i2c_write(0xC1);
i2c_write(0xF1);
data[0] = i2c_read();
data[1] = i2c_read();
data[2] = i2c_read();
data[3] = i2c_read();
data[4] = i2c_read();
data[5] = i2c_read(0);
i2c_stop();
delay_ms(10);
while(1)
{
// JUST FOR TESTING
i2c_start();
i2c_write(0xA1);
i2c_write(0xA2);
i2c_write(0xB1);
i2c_write(0xC1);
i2c_write(0xF1);
delay_ms(100);
//
putc(data[0]);
putc(data[1]);
putc(data[2]);
putc(data[3]);
putc(data[4]);
putc(data[5]);
printf("%x\n",data[0]);
printf("%x\n",data[1]);
printf("%x\n",data[2]);
printf("%x\n",data[3]);
printf("%x\n",data[4]);
printf("<<18F4523 is ready>>\n");
delay_ms(10);
}
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 27, 2013 12:11 am |
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| Quote: | | I don't get any clock output on pin RA6, or pin 25 (TX), or pin 18 which is SCL output ? |
That's what would happen if you were missing the 10K pullup resistor on the MCLR pin. |
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Electronguru
Joined: 26 May 2013
Posts: 11
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| Posted: Mon May 27, 2013 1:08 am |
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| PCM programmer wrote: | | Quote: | | I don't get any clock output on pin RA6, or pin 25 (TX), or pin 18 which is SCL output ? |
That's what would happen if you were missing the 10K pullup resistor on the MCLR pin. |
Thanks for the tip, there was a 10K resistor but I was leaving the MCLR pin connected to PICkit2 and it was pulling it down. Now I do see clock output at RA6.
But no RS232 signals at pin 25 or I2c clk on pin 18 ??
Although this code simulated as expected in Proteus. |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Mon May 27, 2013 10:37 am |
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work better ???
at least for clock out
also consider using
setup_oscillator() per the header file
and
BTW you might want to specify a few more
#fuses
based on what you want to accomplish |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 27, 2013 12:19 pm |
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| asmboy wrote: |
work better ???
at least for clock out
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INTRC is the correct fuse to get a Fosc/4 clock signal on pin A6.
If you use INTRC_IO, the two oscillator pins (A6 and A7) are i/o pins.
If you have the CCS IDE, the fuses.txt file has this:
| Quote: | INTRC Internal RC Osc
INTRC_IO Internal RC Osc, no CLKOUT |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 27, 2013 12:58 pm |
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| Quote: | But no RS232 signals at pin 25 or I2c clk on pin 18 ??
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Do you have pull-up resistors on the SDA and SCL lines ?
If you don't have pull-ups, the i2c_write() function will probably lock-up.
That's because i2c_write() polls the SCL line and if it's low (ie., checking
for clock stretching from the slave), the code will wait in a loop until it
goes high. If there are no pull-ups it will never go high - it will "hang" the
program. This is also true for i2c_read().
Because you have all these i2c lines before your printf statements, I
strongly suspect that you are missing the pull-ups and the program
never gets to the printfs.
| Quote: | | Although this code simulated as expected in Proteus. |
Proteus doesn't care about many hardware issues. Because of this,
many things may work in Proteus but they don't work on a real board.
On a real board, you have to make everything correct. |
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Electronguru
Joined: 26 May 2013
Posts: 11
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| Posted: Tue May 28, 2013 1:12 am |
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Hi,
PCM Programmer, yes you right to point out, I don't have pull ups on I2C. I will put the pull ups now and see if both I2C and RS232 work.
Regards |
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