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marcus02
Joined: 22 Jan 2013
Posts: 7
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| Need help in XBEE with PIC!! |
 Posted: Tue Jan 22, 2013 11:41 am |
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Hi everyone,
I know how to connect XBEE in point to point but I don't know how to use it with PIC16f877A. I've constructed my board with 3.3V to PIC and also XBEE. XBEE connection will be vcc, rx, tx, and gnd.
Here is my test code for both transmitter and receiver.
The xbee is not working. I'm wondering why is it happen.
Hope anyone can give me guide lines. Thanks in advance.
Anyone can show me coding example i will modify myself.
I'm using CCS c-compiler. thanks.
Transmitter:
| Code: |
#include <16f877a.h>
#fuses HS,NOLVP,NOWDT,NOPROTECT,NOBROWNOUT
#use delay(clock=20000000) // 20 MHz crystal on PCB
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7,bits=8, parity=N) // you can use any pins for software uart...
#include <stdlib.h>
void main()
{
while (TRUE)
{
if (input(PIN_A2)==1)
{
output_high(PIN_B0);
printf("a"); //sends signal a
}
else
{
output_low(PIN_B0);
printf("b"); //sends signal b
}
}
}
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Receiver:
| Code: |
#include <16f877a.h>
#fuses HS,NOLVP,NOWDT,NOPROTECT,NOBROWNOUT
#use delay(clock=20000000) // 20 MHz crystal on PCB
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7,bits=8, parity=N)
#define LED_0 PIN_B0
#include <stdlib.h>
char x;
void main() {
while (TRUE) {
if (kbhit()) {
x = getc();
}
if (x=='a'){
output_high(LED_0);
}
else{
output_low(LED_0);
}
}
}
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Ttelmah
Joined: 11 Mar 2010
Posts: 19467
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| Posted: Tue Jan 22, 2013 12:55 pm |
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First thing. Change your PIC......
The 16F877a, is not rated to operate below 4.0v. The LF, is rated down to 3.3v, but at 10MHz max.
Big problem.
Second, add errors to the slave RS232 definition. This must be used when the hardware UART is used, unless you handle errors yourself. Without this the UART can get locked.
Other comment, you only need to change the LED's, when a character has been read. No point in continuously setting them.
Best Wishes |
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Gabriel
Joined: 03 Aug 2009
Posts: 1067
Location: Panama
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| Posted: Tue Jan 22, 2013 2:44 pm |
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in case you are wondering... you could use a 16f887... its a pin by pin drop-in replacement.
also, if you are like me and have PCM, its compatible with your compiler.... (you need a diferent version of CCS for 18 series)
G.
_________________
CCS PCM 5.078 & CCS PCH 5.093 |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19467
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| Posted: Wed Jan 23, 2013 9:35 am |
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It's still not rated for 20MHz at 3.3v though.:
20Mhz operation requires 4.5v min on this chip.
To go to 20MHz on a pin/compiler compatible chip, you need something like the PIC16F1937.
Best Wishes |
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Gabriel
Joined: 03 Aug 2009
Posts: 1067
Location: Panama
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| Posted: Wed Jan 23, 2013 12:20 pm |
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.... indeed it does not run at 20MHz on 3.3V but it does run at a lower frequencies unlike the 877A' which requires the 'LF' variant.
in light of the current code posted, and that he is using 9600 baud rates, i really dont think he _needs_ 20MHz operation...
also, since he was using a 877A, the 887 would be a very smooth transition...
G.
_________________
CCS PCM 5.078 & CCS PCH 5.093 |
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