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[landon]

To polish off my part of this thread and followup on what I found:

Bruce of Rentron sent me a new encoder/decoder (you'll need to contact Rentron to learn more about them.) The ones I got I think were experimental but hopefully close to production - The encoder had a gold dot on it and the decoder had a silver dot on it - that was all there was for a marking on the chips.

These chips are pin-for-pin compatible with the Linx encoder/decoder.

Once I breadboarded them up, they worked flawlessly for what I was planning and they worked fine over the 2400bps low-grade 434 RF radios I got from Sparkfun.

I created two protoboards - a TX and an RX. The TX board has 4 photointerrupter switches that feed D0-D3 of the encoder. The encoder's data out, of course, goes to the data pin of the transmitter.

On the flip side, I wired digital data pin of the receiver to the Data In pin of the decoder. Then strung 4 LEDs off D0-D3.

With this setup, whenever the photointerrupter was blocked, I got a solid LED light on the RX side. This was exactly the behavior I was looking for and couldn't get with the Linx encoders.

Here are the pictures of my latest protoboards.

Transmitter:



Receiver:


Each protoboard has a 434 antenna I bought from Rentron. I've tested these on the bench maybe a foot apart all the way up to maybe 40 feet. One test I did between floors where the two ends were probably 25 feet apart, but separated by a floor.

It was all working very well thanks to the new encoders from Rentron.

Bruce, thanks again for going above and beyond the call of duty and working on this over Thanksgiving weekend to diagnose the issues with the newer radios.

Hopefully, this exercise will be of use to others.

[riden]

Way to go Landon!

I'll check around the lab and see if I can find some Gold and Silver dots to put on my chips. Seriously, Bruce told me that his prototype chips are in the mail to me to replace the Linx chips that I had ordered. I will test them with the various receivers and transmitters I have laying around.

Ralph

[busonerd]

hmm, I would guess those chips are actually just pic12fs of some kind with the label sanded off and a dot added .

the pinout fits with a 12f: [1->Vdd, 8 to GND] .

Cheers,

--David Carne

[Bruce]

Yes these definitely are 12F parts, but we don't try to hide it by scratching or sanding off parts numbers. Way too much effort for a little 8-pin encoder/decoder chipset...

These are just 12F parts with a modified version of our 8-bit encoder & decoder IC firmware, but they work with every RF module set we've tested them with, and we're getting 400 to 500' operating range even with the el-cheapo RF modules.

I doubt we'll ever try labeling them, so the gold & silver ink dots will most likely be what we'll use on them. We've made a very small modification to the firmware since Thanksgiving. The decoder response time is now faster.

[riden]

Well, putting gold and silver dots on the LICAL chips was a non-starter.

Fortunately, I received my chips from Rentron today, and they work great! Rock solid decoding on all four data lines. I tried the four different receivers I had (Rentron's RWS-434, LaiPac RLP-434, Radiotronix RCR-433-RP, and Wenshing RWS-434) at 2400 baud and experienced no issues. When I have more time in a few days, I'll try 4800 baud on my two receivers that support that rate.

My thanks go to Bruce at Rentron for the excellent follow-through on this issue, and for getting the problem resolved so quickly.

[saipan59]

One more bit of data:
Playing with the 4800 baud 434 Mhz receiver modules from SFC, I was trying to figure out the real difference between pin 2 and pin 3.
When I couldn't see a difference on the scope, I noticed that those pins are tied together (there is a visible PC trace between them).

The random signal spends nearly all of its time at '1' or '0', but it does have some positive-going spikes in amongst the noise.

I'm trying to decide if it's worth using a comparator with these particular modules, since they don't really have an analog output... And I'll be using an 18F2620, which has a Schmitt trigger input on the RX line (the trigger values are about 1V and 4V when Vdd is 5V).

And, do the 2400 baud modules actually have an analog output? I gather that they do...

Pete

[riden]

If your receiver only has digital output, then a comparator won't be helpful. You probably have checked this, but are you sure you're not looking at pins 6 & 7 (GND)? I have several 2400 and 4800 baud receivers, and there aren't any jumpers between 2 & 3 on the receivers I have on hand. However, I do have one receiver that has pin 7 as an Enable pin, and if I tie it to ground like my other receivers, the receiver is disabled. None of the data sheets makes any mention of this although the silkscreen labels the pin as E/D.

[saipan59]

These rcvrs are the 4800 baud type, recently got from SFE.
Definitely pins 2 and 3 are connected together.
Both pins are labeled "Data" on the silkscreen.

Pete

[riden]

These rcvrs are the 4800 baud type, recently got from SFE.
Definitely pins 2 and 3 are connected together.
Both pins are labeled "Data" on the silkscreen.

Well, that is pretty conclusive. It sounds like a comparator won't help you here. It is interesting to see how much these receivers seem to change from one lot to another.

BTW, thanks for the tip (on the RF-KLP-315 basics thread) about balancing the data and XORing the incoming stream. I want to try that out on the hardware USART on this end. I haven't had to resort to any special encoding, but I'm using a software UART and they are more tolerant of timing.