Serin Serout possible wiring distance

[tasmod]

I'm using the wireless modules as per a previous post.

Running at 3.3v what length wiring would possibly work ok for Serin/Out.

I need to separate the radio module from the pic by about 3-4 metres, will it work that far?

Rob

[HenrikOlsson]

As with most things it depends....On the baudrate, cable, environment etc etc but most likely yes it'll work just fine. Easy enough to try isn't it?
I've run UART comms (2400 baud, 5V levels) thru ~25m cable and it worked. I can't recommend it though.

[dhouston]

What radio module? What speed? What type cable?

[tasmod]

Sorry here's further details :-

arf-high-power-radio-transceiver

Baud is set at 9600

No cable as at the moment the radio module is inserted on a socket on the pic prototype pcb so is only tracks.

I need to separate the radio with aerial and the pic controller.

There is a switch and two leds for the 'control' pic, which then sends the serial commands to the radio module on the same pcb.

The radio module is connected to a yagi aerial at 450mm long overall which needs to be at least 3m in the clear.

Due to cable losses at 868Mhz it's not reasonable to use coax, so the radio module is in a weatherproof box and connected with 50mm of coax to the aerial. At the moment during testing it's also the pic pcb.

With one yagi and a loop on other module I've reached 865m, which is two way. 'Control' sends signal and 'receive' acknowledges back to action a led.

865m is not it's range limit, it's the farthest distance I can use control module due to running off a cigar lighter plug in car.

I need a small battery pack for the control so I can go farther on foot for testing, I have the 'receive' part connected to my psu at home and at the moment drive off to location that's line of sight.

I will try to post pictures of the modules.

Rob

[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.