Serin Serout possible wiring distance

[tasmod]

Pictures of the prototypes. The 9db gain yagi aerial is made from oval plastic electrical conduit using UK 2.5mm twin and earth wire for the elements.
The coax and super mini plugs were from a junk laptop wifi aerial. It's the grey lead on the loop aerial on the 'receive' board.

The pic controller is in the box at the moment with the switch showing, the leds are on board for now. The switch and leds need to be in a desktop box with the pic and the radio module left in the box with the aerial. Nothing is yet sealed, it will be later with a hot glue gun.

I've made the pcb's with a set of pads on the connecting tracks so that the boards can be cut and wire used to connect. They can be just made out on 'receive' board.
The red led on the 'receive' board is a 'heartbeat' led that confirms radio module operating.





The loop is a 3db gain Moxon rectangle.

[dhouston]

Unfortunately, Ciseco has no downloadable documentation, as yet. However, the link you supplied does say it is UART RS232 so you really need to know whether it is outputting RS232 voltage levels which will fry your PIC unless you use something like a MAX232 converter. It it outputs TTL, you still need to know the voltage levels. 5V may be too much for your 3V PIC. If 0-3V yuu need to see what voltage is needed for the PIC to see a logic high as the voltage may be marginal over your cable as TTL devices seldom output rail-to-rail voltages.

[tasmod]

Thought I posted that. Radio module is available 3.3v only.

So Pic and radio module are at 3.3v. Voltage reg in photos is 3.3v device.

I wanted to separate the modules but I can instead separate the switch and leds and leave rest at aerial.
Not ideal though. Hopefully thicker cable will ensure low volt drop for leds ...

It's only for the 'control' the 'receiver' is ok as a boxed item, the relay is needed at top of mounting pole anyway. It's a 3.3v board from Ciseco.

[dhouston]

Thought I posted that. Radio module is available 3.3v only.

So Pic and radio module are at 3.3v. Voltage reg in photos is 3.3v device.

That doesn't necessarily mean that RX & TX are at 3.3V. The purpose of chips like the MAX232 is to boost the supply voltage to RS232 levels which can be +/-15V.

However, since the ARF is an upgrade of Ciseco's XRF, it probably is wired the same and there is documentation for the latter showing RX & TX directly connected to the microcontroller. It would help if they correctly identified their devices as using a low voltage serial link rather than being RS232 which implies much higher voltage levels.

As Henrik said, the only way to be sure is to try it. The TX level is likely to be ~3V at best. You can check the PIC datasheet to see if that's adequate.

[tasmod]

Thanks Dave,

Hmmm Ciseco documentation. Good overall, but very confused descriptions with various devices being refered back to each other. Lots of back and forth. It strikes me of someone who knows their products, but forgot to ask someone who doesn't know to look at the site.

I was reluctant to split the board as it's a nice fit in box but it's now getting too close to deadline, so I'll try the cable route.

Rob

[tasmod]

Just for information if anyone wants to use these rf modules. I did a range test of the modules with the shown aerials.

4.687km line of sight with reliable operation.


Just modding the boards to test serial cable length working between pic and rf module. I will try 5m cable length, as that's what is required on site.

I'm also looking at providing RSSI on a lcd display. I need to add AT commands in code to switch the other transceiver into test mode where RSSI is sent every second.

Just need to work it out.

[Ioannis]

Very impressive range. Can you give us your antenna calculations?

I just have succesfully tested a pair of Adeunis ARF7761 modules at 169MHz@500mW that covered over 12Km range. One side used a 42cm l/4 atached on a short RG58 cable and the other a dipole l/4.

Ioannis