RF Modules

[ruijc]

Hi Joe S.,

the modules are connected directly to the pics.

One thing i noticed and i found it weird is that when turning the power on the receiver ( and always the RX - never happened to the TX ) sometimes does not start receiving ( although the TX is transmitting ).

My workaround is to turn power off for a couple of seconds and reconnect power ( and sometimes i have to do this 2 or 3 times ).

I changed modules, experiment board, etc and this only happens on the RX side.

Should it be any startup procedure sequence for the RX ?

[Archangel]

I changed modules, experiment board, etc and this only happens on the RX side.

Should it be any startup procedure sequence for the RX ?

Not sure if you mean the PIC or the transceiver. The PIC RX using HSERIN <font color=red>REQUIRES a pullup to VDD </font color>or you will get an intermittent (if at all) PIC boot. If this causes problems with the radio, you can use something to buffer the link, Tristate buffer ? I discovered this a long time back with my serial LCD project. You could "buffer" it with a simple transistor, but would then be dealing with inverted serial data.

[ruijc]

I mean the transceiver.
I have a LED connected to BUSY output of the transceiver on both ( RX and TX modules ).
The RX transceiver blinks the LED everytime the TX sends data. But this doens not mean the PIC shows the correct DATA on LCD ( sometimes no DATA at all ).

And sometimes when powerup, the RX transceiver does not blink ( pic and LCD working OK ).

I'm using DEBUG/DEBUGIN instructions to avoid issues with Hserin/Hserout.

[Archangel]

OK then maybe you need more hysteresis to your power up cycle, which is to say the rate the voltage ascends from zero to operating voltage. Many MCU do not like slow power up, which is why PIC has PWRTE in the configs, it allows power to stabilize before PIC boots, or there may be RF running in on the power causing headaches, you did bypass the power leads with .01 &micro;F caps yes? A ferrite bead there wouldn't hurt either.

And sometimes when powerup, the RX transceiver does not blink ( pic and LCD working OK ).

I'm using DEBUG/DEBUGIN instructions to avoid issues with Hserin/Hserout.

Be mindful of the Port Idle state, whether using hserin or debugin, True is supposed to Idle high and Inverted is supposed to idle low. So use the state which agrees with your receiver's requirements.

[ruijc]

Hi Joe,

I'm using the same power supply for both.

I'm using a 7805 with 220uF cap and 2 diodes to lower the VCC to the transceivers.

About the port idle state...good call

i've set the port pins high at the beginning of the code for both ( TX and RX pics ) but the result is still the same

[Archangel]

Hi Joe,

I'm using the same power supply for both.

I'm using a 7805 with 220uF cap and 2 diodes to lower the VCC to the transceivers.

About the port idle state...good call

i've set the port pins high at the beginning of the code for both ( TX and RX pics ) but the result is still the same

Setting them high is not enough, use pullup or pulldown resistors, depending on what state is required.

[ruijc]

Hi Joe,

I've placed 0.1uF caps on each transceiver VDD and GND pins.

Also placed a resistor on the receiver side as a pullup for the RX pin.

Still i get intermittent and incomplete data