Replacement RF Modules (2.4 GHz ?) - Page 1
Forum section: electronics / projects

author: David_AVD
author_rank: Super Contributor
timestamp: March 05, 2013, 07:01:50 am
content: Has anyone come across these RF modules? Seems to be from an Asian supplier but scant details available.I could use something else as I have access to both ends of the link. Baud rate is 9600 and I think it's a 5V module.

author: mamalala
author_rank: Unknown
timestamp: March 06, 2013, 02:02:17 pm
content: How "intelligent" do you need the module? Hope-RF has a series of rather cheap 2.4 GHz modules, but they are SPI interface only, so you would need to do some programming on a µC yourself to get them working:http://www.hoperf.com/rf/24g/There is also the slightly older RFM70 from them, goes for less then 4 Euro here in Germany, for example:http://www.pollin.de/shop/dt/MDU4OTgxOTk-/Bausaetze_Module/Module/Funkmodul_RFM70_Sende_Empfangsmodul.htmlIf you need modules with more intelligence, you may want to check out Rayson:http://www.rayson.com/Greetings,Chris

author: David_AVD
author_rank: Super Contributor
timestamp: March 06, 2013, 09:07:38 pm
content: Some clarification:The original modules have been damaged by water ingress and subsequent corrosion. One of them is in a scoreboard controller and the other is in a (football) scoreboard.I have no access to the firmware on either side, so the modules just need to provide a simple 9600 8N1 link over a 60 - 70 metre range.Maybe a "paired" set of 2.4GHz radio modems would work. The original ones have ABCDE jumpers that may have set some sort of address / logical channel.

author: MikeK
author_rank: Super Contributor
timestamp: March 06, 2013, 10:09:21 pm
content: If you don't have access to the firmware how can you be sure of the protocol of the data being sent/received? Unless you got the exact same RF devices, I don't see how you could do this without having access to the firmware.You might have to sniff the bus to see what's going on and then implement a MCU/RF solution at each end.

author: David_AVD
author_rank: Super Contributor
timestamp: March 06, 2013, 10:30:09 pm
content: Very easy Mike. The modules has TTL level I/O. I used my comms tool to check the data.There doesn't seem to be any configuration data going to the module upon power up. (like an AT command set) All data from the start is purely scoreboard data.

author: mamalala
author_rank: Unknown
timestamp: March 07, 2013, 12:39:04 pm
content: Then maybe a module like the BTM222 from Rayson might be the answer. It provides TTL UART on one end, and uses the high power class Bluetooth on the RF end (but not sure if that is enough to cover the distance you need). You would do the pairing manually first. I think they can do some kind of auto-connect, but not really sure. In any case, the end result would be a transparent serial link between two modules.But you could also do a small adapter board where you put a RF module plus a small µC. The µC would handle the comms and stuff for the RF on one side, and provide an UART interface on the other. I could provide you some code i have written for the RFM12 series of RF modules (433, 868, 915 MHz) that would basically do exactly that with a small PIC micro (albeit i use USB instead of UART, but shouldnt be a problem to swap that part out).Having such modules/adapters might be useful for your own projects as well...Greetings,Chris

author: David_AVD
author_rank: Super Contributor
timestamp: March 07, 2013, 09:03:46 pm
content: Thanks for your reply. Was hoping for an off-the-shelf solution that I can jam in there and get this system repaired and working ASAP.I found some Handywave Handyport devices that will do the trick, but since they are RS232 I'll have to use a couple of small RS232-TTL boards as well.Part of the problem is that I only have the score console part here. The scoreboard is large and fixed to the venue so I need to go back out there (few hours round trip) with whatever is needed to make it work.

author: mamalala
author_rank: Unknown
timestamp: March 07, 2013, 09:41:15 pm
content: I'm wondering what the "real" RF module on the unit you showed is. Can't really see it since the image is so small, but to me it looks like the whole thing is just a breakout board that contains a small µC (the SMD IC on the leftmost side) and a "regular" RF module (the metal can right next to the IC). If that is the case, maybe the RF module itself is still available somewhere and can be replaced on that breakout board?Greetings,ChrisEdit: Also note that there is a lot of rust/corrosion at the lower-left part of the metal can. It is spread out over the PCB, and seems to even flow under the crystal. Maybe some cleaninng up and checking for broken traces will do the trick already? I can imagine that the crystal/osc won't work anymore due to that brown gunk messing it up.

author: David_AVD
author_rank: Super Contributor
timestamp: March 08, 2013, 12:06:14 am
content: You can click on small images in posts to show the full sized version.Yes, both units are corroded beyond repair.

author: Psi
author_rank: Super Contributor
timestamp: March 08, 2013, 12:09:56 am
content: Does it need to be 2.4ghz?Sparkfun sell one or two serial RF modules at 433mhzThis one looks to do a simple 9600 baud link between two moduleshttps://www.sparkfun.com/products/155

author: Thor-Arne
author_rank: Unknown
timestamp: March 08, 2013, 12:15:24 am
content: TheACP220might be a solution to.I've used this on the arduino only connecting the rx/tx pins.

author: David_AVD
author_rank: Super Contributor
timestamp: March 08, 2013, 12:25:44 am
content: Thanks for that link. Might be too high power to use over here, but it shows that there are similar modules available.

author: David_AVD
author_rank: Super Contributor
timestamp: March 08, 2013, 12:27:56 am
content: Finally managed to get onto the scoreboard company (after many emails and calls) and they actually may have something to plug straight in.

author: Smokey
author_rank: Super Contributor
timestamp: March 08, 2013, 12:43:26 am
content: You really should tell us what company makes the scoreboard and the model number so we can all check if our old high schools have scoreboards we can remotely hack

author: TerminalJack505
author_rank: Super Contributor
timestamp: March 08, 2013, 01:02:40 am
content: This post piqued my curiosity about these RF modules. Something I found amazing is that the 900MHz transceivers can legally (in Canada, US and Australia) transmit at up to 1 Watt!Put one of those in the scoreboard and you can control it from the next city over.

author: David_AVD
author_rank: Super Contributor
timestamp: March 08, 2013, 01:07:02 am
content: Quote from: Smokey on March 08, 2013, 12:43:26 amMost of the systems we service are indoor types and usually have hard wired data links.This one is RF as it's probably too hard (and expensive) to cable from one side (scoreboard) of the football field to the other (controller in scoring shed).