rfPIC Serin problem

[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

[Bruce]

we only see a digital signal 0 1

You should be seeing a digital signal if you're placing a scope probe on GP2. This is a digital
I/O-pin connected to pin #14 DATAask on your tx board. That's your outbound data being
used to control the PA.

Read the data sheet, section 9.4, ASK Modulation and you'll see why an I/O-pin
would be connected to pin #14.

You can find a modulated signal on the antenna output, but you'll be loading it with your
scope probe.

[onepiece]

Hi
I would like to test whether my rfpic12f675 an rfrxd0420 works according to the demo for the development kit. The part for LED indicators on the Pickit Flash 1, it says that when my GP buttons on transmitter are pressed, LED will be lite up. Does that mean that we can just verify this through the dev kit? The LED on my board sometimes toggle when I press the switches, and I thought I should have got a 7 LEDs to light up.
I'm confused at the part where I need to use PIC16f676 for the rxrfd420, do I need to connect the pins RA5 to RC 2 to the PIC itself? Can anyone help me please.

[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.