I want to start playing with bluetooth connectivity. Are bluetooth modules backwards compatible, i.e. Can the HC-06, HC-05, etc... talk with older iOS devices (Bluetooth 2.1) or would specific modules be needed to communicate with older generation bluetooth devices?
Thanks!
HC-05 and the likes implement the SPP profile which has never been supported by Apple
if you want to discuss with iOS devices, go for BLE
Thanks. Im completely new to this so I am still trying to work out how to do bluetooth. All of the tutorials for the HC-06 use android devices. Now I know why 
Im not even sure if this question makes sense, will the HC-10 work with basically all generations of iOS devices? This old iPad I have here says it is bluetooth 2, but the HC-10 data sheet says it is bluetooth 4 — I just don't know if they are interoperable.
what's "an old iPad" ?
iPad from the 3rd generation have BT4.0 support, so BLE too. Only the 2nd generation iPad and original iPad shipped with Bluetooth 2.1 and iOS was pretty strict about what you could pair (it had to be very well defined profiles like Audio and you could not extend those)
it does not help much then, does it? 
In practical terms, the HC-05 has an SPP profile. iOS does not support SPP.
you need a MFi licence and bluetooth module from a certified vendor if you want to develop a product - which is probably beyond the business of 99.9999% of the people here.
Going BLE is what Apple recommends but it was not supported before the 3rd generation of iPads...
you can't. (or define what 'connect' means)
I'm not sure what you mean.
Your pairing request is just going to be ignored as there is no profile matching a supported profile
glad for you.
post code, pictures, information that can be acted upon if you want further discussion
ok thanks and let me think about it as i don't know where i stand with apple if i do so.
Get an HM-10 or AT-09. The use BLE and I currently have one module connected to my iPhone
Where you stand with Apple is nowhere, immaterial, and irrelevant. Where you stand with yourself is the real problem. Replies #2, #6, #8, and #10 are all pretty short, clear, not too taxing to read, and will save you, and others, further grief.
as i don't know where i stand with apple if i do so.
Unless you are an apple employee, or have contractual obligations towards Apple (like if you are bound by the MFI agreement) it is likely indeed irrelevant.
There are ways to do stuff with BT but Apple has (rightly so in my opinion) put constraints on who can get the entitlement and bundle that in a shipping app (and not a side hack you compile locally on a (jailbroken-able) very old iPad as OP was referring to).
If you found a way to circumvent this and exchange data with a non supported BT profile within the current OS and standard developer entitlements then indeed it should not be discussed in any details and you should send documentation to Apple’s bug bounty program and can make solid bucks out of it possibly (Bounty - Apple Security Research)
I'm not a lawyer... can't say.
okay i will try and find out and let you know thank you.
hi and thanks for the info.
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