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biomed12
Joined: 05 Feb 2016
Posts: 33
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| what is the problem? |
 Posted: Sun Apr 17, 2016 5:46 am |
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Hello everyone,
I have been working with p16f877 until now. I tried to compile similar code for 18f4550. But there should be a problem. What is the problem, uart module doesn't work properly. code for adc and sending it to rs232 and works perfect for 16f877a
| Code: |
#include <18F4550.h>
#device ADC=10
#fuses HSPLL,NODEBUG,NOCPD,NOPROTECT,NOPUT
#fuses pll4
#FUSES NOWDT //No Watch Dog Timer
#FUSES WDT128 //Watch Dog Timer uses 1:128 Postscale
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOXINST //Extended set extension and Indexed Addressing mode disabled (Legacy mode)
#use delay(crystal=10MHz)
#use delay(clock=40MHz)
#define LED PIN_B0
#define DELAY 1000
#use rs232(baud=57600,xmit=pin_c1,rcv=pin_c7,parity=N,stop=1)
#include <main.h>
unsigned long int adcdeger;
unsigned char veri[8];
void main()
{
setup_psp(psp_disabled);
setup_spi(spi_ss_disabled);
setup_timer_1(t1_disabled);
setup_timer_2(t2_disabled,0,1);
setup_timer_3(t3_disabled);
setup_ccp1(ccp_off);
setup_ccp2(ccp_off);
setup_adc(adc_clock_internal);
setup_adc_ports(an0);
set_adc_channel(0);
delay_ms(1);
//Example blinking LED program
while(true)
{
adcdeger=read_adc();
//delay_us(10);
sprintf(veri,"%ld",adcdeger);
puts(veri);
output_b(0x01);
delay_ms(100);
output_b(0x00);
delay_ms(100);
}
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Apr 17, 2016 9:39 am |
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The basic problem is you didn't read the oscillator section of the 18F4550
data sheet.
You can't run the PLL from a 10 MHz crystal. The crystal must be a
4 MHz, or a multiple of 4 MHz (reduced to 4 MHz by a PLLx prescaler fuse).
The CPU clock from the PLL is not 40 MHz. It's 48 MHz or a lower value
created by a divisor (specified by a CPUDIVx fuse).
This post shows how to run the 18F4550 in non-PLL mode and in PLL mode
with a 20 MHz crystal:
http://www.ccsinfo.com/forum/viewtopic.php?t=42223&start=1 |
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biomed12
Joined: 05 Feb 2016
Posts: 33
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| Posted: Sun Apr 17, 2016 1:20 pm |
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| PCM programmer wrote: | The basic problem is you didn't read the oscillator section of the 18F4550
data sheet.
You can't run the PLL from a 10 MHz crystal. The crystal must be a
4 MHz, or a multiple of 4 MHz (reduced to 4 MHz by a PLLx prescaler fuse).
The CPU clock from the PLL is not 40 MHz. It's 48 MHz or a lower value
created by a divisor (specified by a CPUDIVx fuse).
This post shows how to run the 18F4550 in non-PLL mode and in PLL mode
with a 20 MHz crystal:
http://www.ccsinfo.com/forum/viewtopic.php?t=42223&start=1 |
Thanks sir, i almost left using of the ccs because of this reason. I am student and have been working for 6 months with 16f877 and 16f628. 18 series has lots of differences from 16 series, even banks mapping. Everything is ok and works properly now. Thanks again. |
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temtronic
Joined: 01 Jul 2010
Posts: 9246
Location: Greensville,Ontario
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| Posted: Sun Apr 17, 2016 3:57 pm |
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If you've chosen the 4550 for USB use, be aware that 1/3 of the code space will be taken up by the USB 'driver' ! Once I discovered that few years ago, I then chose the 18F46K22, 40 pin DIP, and a TTL<>USB module.
Benefits include faster, more powerful PIC with LOTs of memory and peripherals (2 HW UARTS, 2SPI, etc....). NO space required for USB (it's all in the TTL<>USB module. Cost is only $1 more when you consider you need USB connector, 2-4 Rs, 2-3 Cs, an LED or 2,... and hoping you don't connect D+ to D-, D- to D+ on your PCB layout ! Also the 18F46K22 works at 3V or 5V, so it easily interfaces to 3V devices like GPS, RFID, RFUARTs, etc.
Just something to consider.
Jay |
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biomed12
Joined: 05 Feb 2016
Posts: 33
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| Posted: Sun Apr 17, 2016 5:17 pm |
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| temtronic wrote: | If you've chosen the 4550 for USB use, be aware that 1/3 of the code space will be taken up by the USB 'driver' ! Once I discovered that few years ago, I then chose the 18F46K22, 40 pin DIP, and a TTL<>USB module.
Benefits include faster, more powerful PIC with LOTs of memory and peripherals (2 HW UARTS, 2SPI, etc....). NO space required for USB (it's all in the TTL<>USB module. Cost is only $1 more when you consider you need USB connector, 2-4 Rs, 2-3 Cs, an LED or 2,... and hoping you don't connect D+ to D-, D- to D+ on your PCB layout ! Also the 18F46K22 works at 3V or 5V, so it easily interfaces to 3V devices like GPS, RFID, RFUARTs, etc.
Just something to consider.
Jay |
These considers are unvaluable for me. I have been working with serial communication module for my little projects. One of the big reasons for starting to use p18 series is definetely its USB properties. I saved your suggestion to use when i need.
Thanks very much. |
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