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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.

Kongress
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  • As you said, the only way to do it (if you can't find something on the internet) is to build it yourself through their hardware development program. (And, via bluetoooth, I don't think you'll have any luck, you're going to have to do hardware that attaches to the phone through the docking connector) – KevinDTimm Sep 14 '11 at 18:08
  • You may want to check on the bluetooth restrictions. I think they only want you to stream audio via bluetooth. Just double check. – Sam Sep 14 '11 at 18:59
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    @Sam as long as you have an authentication chip from apple you can use bluetooth for whatever you want. Been there, done that. – Matthias Bauch Sep 14 '11 at 20:25
  • @fluchtpunkt When you say "been there done that" do you mean that you've used the Apple authentication chip? If so, ballpark, what sort of level of effort was involved? – Kongress Sep 15 '11 at 13:33
  • Since I have worked as an independent contractor for a company that is a member of the MFi program the only thing I had to do is read the documentation and implement the software. I can't say anything about the process of becoming a MFi member. – Matthias Bauch Sep 15 '11 at 14:03

6 Answers6

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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)

Matthias Bauch
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  • 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 Sep 15 '11 at 13:41
  • @Kongress So what did you end up doing? – Eternal21 Dec 20 '16 at 13:03
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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.

mringwal
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  • 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 Sep 19 '11 at 18:15
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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.

mringwal
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    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." – Kongress Sep 20 '11 at 12:43
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    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). – mringwal Sep 20 '11 at 14:36
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This product works: https://serialio.com/product/bluetooth-serial-adapter/bluesnap-smart-bluetooth-40-ble-rs232-adapter

The only downside is that the adapter requires power.

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Eternal21
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It should be possibly I would think to create something in the middle that accept the bluetooth commands and convert them to serial, similar to what this does with TCP connections: https://www.npmjs.com/package/stellar-socks

nmajin
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Well. It seems like my answer could be something you didnt ask for. But the guy you referred to is the answer. Buy his product and you are good to go, all you need is a MAX232 chip. Converts logic level UART to RS232. the diffrence high + voltage low zero voltage is converted to high +~10volts low -~10volts.

I use the MAX232 chip with my microprocessor, that uses logic level USART to communicate over RS232.

There is a lot of tutorials out there explaining how to hook things up.

David R.
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  • 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 Sep 19 '11 at 12:58