iPhone to RS-232 via Bluetooth

Question

I'm looking to connect my iPhone to an RS-232 serial device via Bluetooth. Has anyone implemented this successfully and can offer advice on hardware to use? It's kind of tricky because of the need for the Apple Authentication Processor with the device. The best potential device I've found is this guy but it only comes in an embedded package, its serial port interface is just logic-level UART rather than line-level RS-232, and I can't find a supplier with it in stock.
Any thoughts would be appreciated.

I'm considering just using WiFi to serial instead, but please ignore that possibility for the purposes of this question.

Solution 1

most of the question was answered by yourself already.
Basically you have 5 (+2) choices.

1. Join the MFi program. This might be hard to impossible if you are not part of a at least mid-size company.

2. Buy the OEM Bluetooth Module. I'm not sure if this is even allowed by the apple policies.

3. Use WiFi. Keep in mind that you want to use a wifi chipset that can act as at least ad-hoc access point. Those chipsets are quite expensive, and you have to think of a way to join existing networks (customers don't want to leave their home network to use your product). This will add a lot of cost to the BOM of your device.

4. Jailbreak might be an option. I never tried to use accessories with a jailbreak, so I don't know if it's possible to use bluetooth without authentication.

5. Work with a company that is member of the MFi program.

6. (Maybe an option, and depending of the speed you want to have via RS232: Eventually you can convert the audio output of the head-phone jack to RS232 levels and vice versa)

7. (Not really an option: develop for Android and do whatever you want)

Solution 2

Ok. Another option. There are one or two companies that sell RS232 cables for iOS, eg. Skywire here: http://www.southernstars.com/products/skywire/index.html

Then, you could uses a Bluetooth RS232 extender, which consists of a RS232-to-SPP and a SPP-to-RS232 pair. Ugly, but within Apple's rules.

Solution 3

If you jailbreak your device, you can use BTstack.org (disclaimer: I'm the author of BTstack) to connect to a Bluetooth device that supports the Serial Port Profile. You can get Bluetooth Modules that implement SPP and provide UART level output. As David R. above points out, you then need a UART to RS232 converter, e.g. the MAX232.

Comments

[Kongress]

1. Yup, we're probably too small to make this happen. 2. Or if I can even find one in stock. They mention an Apple royalty fee, so that's probably enough to keep Apple happy (and increase the cost). 3. This may be where I end up. The WiSnap WiFi to serial module looks doable, but still pretty expensive as you said. 4. Customers probably aren't going to go for that. Interesting thought, though. 5. Any suggestions? 6. Probably too complicated/too much effort for this application. 7. That may happen too. We could then get a mil-spec handset as well...

[Kongress]

Have you used the board I linked to? I'm still leery of the cost and complexity of using that board (paying Apple royalties, making sure the auth co-processor is set up right) until I hear from someone who's already done that. The logic level to 232 is not a huge hurdle, as you pointed out, more of a minor annoyance.

[Kongress]

I appreciate the thought but it's unlikely that I'll be able to get my customers to accept the requirement of jailbroken phones for this application.

[Kongress]

Also interesting, but this part seems a bit problematic: "Please note that due to Apple's policy restrictions, you can only develop apps that work with Redpark's cable for your own personal use. Such apps cannot be sold on the iTunes Store. If you want to sell an iOS app which uses Redpark's serial cable, you'll need to develop your own "flavor" of the cable. Contact Redpark for more information."

[mringwal]

I know, but you could use that at least in-house without Jailbreak. Otherwise you'll need to go Wifi or join Made for iPhone (which is not possible for most small companies).

[Eternal21]

@Kongress So what did you end up doing?