rfPIC Serin problem

[gavo]

Hi All, I have been having some problems trying to send and receive data using the rfPIC16F675K and the rfRXD0420, I have been trying to use the serin command to read the data i have sent using the serout command:

pulsout porta.2, 1
SerOut PORTA.2,n2400,[$55,$55,"A",B0]

when I use the serin2 command to wait and to receive "A", it seems like it does not work

SERIN2 PORTC.1,n2400,1000,loop1,[WAIT("A"),B1]

i have also tried the pulsin command but seem to be getting nothing, does anyone have some ideas?

Many Thanks,

Gavin

[mister_e]

This should work... but as we don't se the whole code, it's hard to tell if you don't have anything missing in it. Make sure you have disabled all analog stuff on the pin you're using and it should be ok... unless i missed something

[gavo]

Hi Steve,

Many thanks for the reply ;-)

Please find below:

Transmitter Side

INCLUDE "modedefs.bas"
DEFINE OSCCAL_1K 1

TRISIO.0 = 1 ' set GPIO.0 as input
TRISIO.2 = 0 ' set GPIO.0 as output

B0 VAR WORD

start:

PAUSE 500
HIGH PORTA.5
PAUSE 500
LOW PORTA.5
PAUSE 500
HIGH PORTA.5
PAUSE 500
LOW PORTA.5
GOTO loop

LOOP:

PAUSE 500
LOW PORTA.5
IF PORTA.3 = 0 THEN GOTO LOOP1
IF PORTA.3 = 1 THEN GOTO loop

LOOP1:

HIGH PORTA.5
SerOut PORTA.2,n2400,[$55,$55,"A",B0]
Pause 100
GoTo LOOP

End
INCLUDE "modedefs.bas"


trisa = %00111111
trisc = %00111111

B0 VAR WORD
B1 VAR BYTE
B2 VAR BYTE
Pause 100

start:

high porta.4
low porta.1
pause 500
low porta.4
high porta.1
pause 500
high porta.4
low porta.1
pause 500
low porta.4
high porta.1
pause 500
GOTO loop

loop:

SERIN2 PORTC.1,N2400,1000,start,[WAIT("A"),B1]
GOTO LOOP2

loop2:

low porta.4
high porta.1
pause 3000
high porta.4
low porta.1
pause 3000
goto START


End

Receiver Side:

[gavo]

Hi steve,

I have been running the code again and it seems to get stuck on the the receive side in the line of:

SERIN2 PORTC.1,T2400,1000,start,[WAIT("A"),B1]

The code seems just to hang, it does not even run to the label "start" i am using the PIC16F676, any ideas why it is doing this?

Regards,

Gavin

[Bruce]

PORTC.1 on the 676 is an analog input by default at power-up. It will always read 0 until
you disable its A/D function.

The rfPIC12F675K also has A/D you may need to disable.

[gavo]

Hi Bruce,

Many thanks, i will try that ;-)

Regards,

Gavin

[medusa2584]

does anyone know how to calculate the transmission bitrate for rfPIC12F675?

and im confuse about one thing. if the datasheet says it would transmit data in 433.9 mHZ, is that referring to the frequency band or the carrier frequency.? as far as i understood, it is the frequency bandwidth, and the carrier frequency depending on the oscillator that we used. isn't it??? can anyone please confirm this to me??

do you know the range of data can be transmitted by rfPIC12F675??

thank you in advance

[Bruce]

The transmit frequency = RFXTAL frequency * 32. This can be trimmed by the value of C1 as shown in the chart. This is the carrier frequency for ASK modulation.

ASK transmits at the center frequency. FSK transmits a few kHz from center frequency. This is explained in the data sheet.

The bit-rate data is transmitted at depends on your firmware. If you look at the Microchip code examples you'll see how they use delays between toggling the data pin to set the bit- rate. 40 kbps is the upper limit.

What you'll have for operating range will vary like the wind depending on your finished RF design, voltage on the PS pin, and a boat-load of other factors like receiver sensitivity, operating environment, antenna design/selection, etc, etc,.

[medusa2584]

thank you very much for the reply..

i have one more question..im testing the rfPIC development kit right now with the demo program..we are trying to test the rf12F675 by using oscilloscope by conneting the probe to the pin output which is pin GP5 and GP0. however, we see no signals output from the transmitter except the analog voltage value 1.29 mv which i think comes from the power supply.

any suggestion how to test it? we have checked the connection circuit many times..but it still give us the same result

[Bruce]

You must have a different rfPIC development kit than the one I have. GP0 on mine connects
to POT0. GP5 to the RFENA pin?

Here are the pin definitions in the Microchip demo tx code example;

#define POT0 GPIO, 0 ; (Analog Input) Potentiometer GP0
#define POT1 GPIO, 1 ; (Analog Input) Potentiometer GP1
#define TXD GPIO, 2 ; (Output) Transmit Data
#define PB3 GPIO, 3 ; (Input Only) Push button switch GP3
#define PB4 GPIO, 4 ; (Input) Push button switch GP4
#define RFENA GPIO, 5 ; (Output) RF Enable

I also have a full schematic in .PDF format on my CD that verifies this.

Have you tried placing the scope on GP2?

[medusa2584]

yup we did try..but we dont get the expected signal..

am i right if im expecting a modulated signal came out from the output channel? so i should be able to see an analog modulated signal with ASK. but, we only see a digital signal 0 1 which i think comes from the power supply that we used.

im sorry..i gave the wrong information. we are using the same develoment kit as yours

thank you

[medusa2584]

thank you very much for the reply..

i have one more question..im testing the rfPIC development kit right now with the demo program..we are trying to test the rf12F675 by using oscilloscope by conneting the probe to the pin output which is pin GP5 and GP0. however, we see no signals output from the transmitter except the analog voltage value 1.29 mv which i think comes from the power supply.

any suggestion how to test it? we have checked the connection circuit many times..but it still give us the same result

does anyone know why we have to times it by 32? i have looked at the datasheet, but it does not state the reason anywhere.

[Destovi]

Hi all I am currently working on a project using the rfPIC micro. I am wondering if anyone has done any work with this PIC without using the dev board. I want to build the circuits myself and program them to work. if anyone has done this and can give me some assistance it would be greatly appreciated.

Thanks