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rald
Joined: 04 Sep 2013
Posts: 25
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| pic18F4550 RS 232 rare issue |
 Posted: Sun Mar 12, 2017 11:32 pm |
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Hello everyone,
I hope someone can help me with this strange thing.
I have a pic18F4550 using a crystal 4Mhz configure for 32Mhz PLL, I am just trying to send data via rs232 TTL to other rs232 TTL.
What is weird is that I can send data with no issue however if I try to receive data nothing happened. I attaching the code.
| Code: | #include <18F4550.h>
#device ADC=10
#FUSES PLL1
#FUSES XTPLL
#FUSES CPUDIV3
#FUSES NOWDT //No Watch Dog Timer
#FUSES WDT128 //Watch Dog Timer uses 1:128 Postscale
#FUSES NOIESO //Internal External Switch Over mode disabled
#FUSES PUT //Power Up Timer
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOVREGEN //USB voltage regulator disabled
#FUSES NOPBADEN //PORTB pins are configured as digital I/O on RESET
#FUSES NOMCLR //Master Clear pin used for I/O
#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(clock=32MHz, crystal=4MHz)
#use rs232(baud=115200,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8,stream=PORT1)
void main(){
char dato[4];
while(TRUE)
{
printf("hola mundo\r\n");
if(kbhit(PORT1) == true){
gets(dato);
printf("%S\r\n", dato);
}
delay_ms(1000);
}
} |
What is even more unusual is that kbhit() works fine but I can not get the char.
I already check the crystal (4MHz), capacitor (33pF), connectivity between pins and the hardware.
any idea?
please help.
thanks. |
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temtronic
Joined: 01 Jul 2010
Posts: 9097
Location: Greensville,Ontario
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| Posted: Mon Mar 13, 2017 5:37 am |
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this...
gets(dato);
says to get a string of data, so it'll stay in a loop until it receives a RETURN (13). It 'should' be looking at your 'stream' for this data but check with the CCS manual for options.
BTW using gets() without a timeout function is not recommended.
ALSO you need to add 'errors' to the uses rs232(...options...), manual explains why.
Jay |
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rald
Joined: 04 Sep 2013
Posts: 25
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| Posted: Mon Mar 13, 2017 9:54 am |
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hi
thanks for reply.
I add your suggestions to my code
| Code: | #include <18F4550.h>
#device ADC=10
#FUSES PLL1
#FUSES XTPLL
#FUSES CPUDIV3
#FUSES NOWDT //No Watch Dog Timer
#FUSES WDT128 //Watch Dog Timer uses 1:128 Postscale
#FUSES NOIESO //Internal External Switch Over mode disabled
#FUSES PUT //Power Up Timer
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOVREGEN //USB voltage regulator disabled
#FUSES NOPBADEN //PORTB pins are configured as digital I/O on RESET
#FUSES NOMCLR //Master Clear pin used for I/O
#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(clock=32MHz, crystal=4MHz)
#use rs232(baud=115200,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8,stream=PORT1,errors,timeout=100)
void main(){
char dato[4];
while(TRUE)
{
printf("hola mundo\r\n");
if(kbhit(PORT1) == true){
while(gets(dato) != ""){}
printf("char = %s\r\n", dato);
}
delay_ms(1000);
}
} |
nothing changes... the RX is not working at all...
any other idea? |
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temtronic
Joined: 01 Jul 2010
Posts: 9097
Location: Greensville,Ontario
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| Posted: Mon Mar 13, 2017 10:02 am |
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Have a look at the ex_sisr.c example that CCS supplies. It's in the examples folder.
Also what hardware are you using to connect PIC to the other RS232 device ?
Jay |
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rald
Joined: 04 Sep 2013
Posts: 25
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| Posted: Mon Mar 13, 2017 10:09 am |
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I am going to check that example.
the other device is HC-05 bluetooth.
but also I testing with an arduino. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Mar 13, 2017 10:17 am |
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Just try a simple character echo program. Then you don't have to deal
with gets(), buffers, array overrun, or anything. Example:
| Code: | void main()
{
int8 c;
printf("Start\n\r");
while(TRUE)
{
c = fgetc(PORT1); // Wait for a char to come in
fputc(c, PORT1); // Then send it back
}
} |
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temtronic
Joined: 01 Jul 2010
Posts: 9097
Location: Greensville,Ontario
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| Posted: Mon Mar 13, 2017 10:56 am |
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hmmm. HC-05 bluetooth device . Is it a 5 volt device ? Most peripherals these days are 3 volt units. That PIC is a 5 volt device, so if (as I suspect) the HC-05 is 3v, you must use proper logic level conversion between the two units.
The datasheet of the 'HC-05' should/will say.
Jay |
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rald
Joined: 04 Sep 2013
Posts: 25
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| Posted: Mon Mar 13, 2017 12:11 pm |
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dude
Your code is working... IS WORKING!!!!
But I can only received one character per line... how do I add more buffer to rx?
Thanks a lot!!!! |
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temtronic
Joined: 01 Jul 2010
Posts: 9097
Location: Greensville,Ontario
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| Posted: Mon Mar 13, 2017 12:15 pm |
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| ex_sisr.c |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19215
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| Posted: Tue Mar 14, 2017 2:17 am |
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Repeat that about the HC-05....
Be aware that the Arduino, has TTL logic inputs. Vih=2.4v
The PIC serial input has a Schmitt level input. Vih=4v.
Chips that will talk fine to an Arduino, need logic level translation to talk to a PIC..... |
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