RF-KLPA-315 Link Problem

Hello,

I’m trying to get anything out of my RF-KLPA-315 link.

I tried first with just a normal serial link at 4800 baud, but got nothing. I wasn’t too suprised as I had no special protocol on that link.

However I have now tried this setup:

TX is connected to push-button on STK500, RX is connected to LED on STK500. Both are powered from STK500’s 5V source.

The LED is always off. I’ve connected a scope up and see the output is always high (STK500 has inverted logic). No matter how I hit the button, I see no change at all on the output.

I’ve got a handheld radio, and tuned to 315 MHz I can hear a difference between when I hit the button and not. So the transmitter is putting out something…

Should that have somewhat worked?

Regards,

-Colin

Take a look at pins 6 and 7. All the schematics say that these are GND connections. However, the silkscreen on one receiver I purchased had pin 6 labeled E/D (enable, disable). When I grounded pin 6, the receiver was muted. Pulling pin 6 to +5v (via a 1k resistor) enabled the receiver. Be very careful. Check to see if pins 6 and 7 are tied together. If so, DO NOT connect pin 6 to +5v. That was the only receiver wired this way and I could find no documentation anywhere that referenced this “feature”.

Hello,

Thanks for the quick reply. I can confirm by looking at the PCB that pins 1, 6, and 7 are all connected to the ground plane on the receiver.

-Colin

Well, checking for Enable/Disable was worth a try.

Have you tried separating the transmitter and receiver? I have not had to do that, but others have said that it helps keep the receiver from overloading. Perhaps running the receiver without an antenna (for testing) might help.

I presume that you can key the transmitter on and off repeatedly and still see no change on the output? Pin 3 should be the analog (RSSI) output. Does that remain at a steady level too? If you put the scope on pin 2 and leave the transmitter off, you should see random transitions due to noise. Can you confirm that?

edit: I forgot to ask you to confirm that you have a 315Mhz receiver and transmitter. You should see some hint on the SAW resonator or receiver board. In other words, maybe you got a 315Mhz TX and a 432Mhz RX. Not likely, but a possibility.

Hey,

I have tried seperating them up to 5 feet, and right now have no antenna.

I never see any changes on the output due to noise, which I was also expecting.

Both are 315 MHz devices. They both have a A315 sticker on them. As well the transmitter’s crystal is marked 315, and the transmitter is checked with my radio. The receiver has a 4.91477MHz crystal, which x64 = 314.5 MHz.

On my module pin 3 is the same as pin 2 - they are physically connected.

Regards,

-Colin

It sounds like you covered all the possibilities. I’m sure you have this right, but since 2 and 3 are connected (and 6 and 7, and 4 and 5), could it be that you have pin 1 switched with pin 8? It is the last thing that I can think of.

Hmm… not actually sure of the pin numbers. I’ve just been using the silkscreen printed right on the receiver to know the pin functions!

Thanks for all your help!

-Colin

Actually, I have a 434MHz version of this.

When I did a continuity check between pin 2 (Digital out) and pin 3 (Analog out, RSSI), there was continuity, as well as with pins 6 and 7 (+5V).

Just a note, the receiver needs a fairly clean 5V. Ive noticed that underpowering it, even down to 4.5V, it would give me shotty results and sometimes refuse to function.

Hmm, you said

RX is connected to LED on STK500

What is the current capacity of the rx pin? (I assume you mean digital or linear data out) I though it was pretty low (-10 uA for low output V?). I presume that you have the led connected to +5 and the output pin will pull it to gnd. Have you looked at either pin with out the led connected? Hope you haven’t damaged it.

Have you looked at either pin with out the led connected?

Crapola. I always thought the LEDs on the STK500 were buffered, but it turns out not to be the case.

Using a volt-meter everything works as it should :oops: Thanks so much!!!

-Colin