Continued from [4th-gen iPod touch Teardown] Why Does Apple Hide Bluetooth Function? (1).

When I broke down the touch, however, I couldn't find a Nordic Semiconductor's chip. And there wasn't any chip that corresponds to a transceiver IC dedicated to the Nike + iPod capability. It is likely that Broadcom's "BCM4325" transceiver, which provides WLAN capability, is also used for the Nike + iPod capability.

The BCM4325 is a WLAN and Bluetooth combo chip. The new iPod touch probably sends and receives Nike + iPod data by using this Bluetooth hardware. In other words, it runs the "ANT" wireless network protocol for Nike + iPod on Bluetooth. This is possible because the protocols of ANT and Bluetooth have much in common.

Q: So you mean to say that the iPod touch is equipped with Bluetooth hardware, even though there is no mention of Bluetooth in the specifications on its catalog?

A: That's right. It means that Apple is limiting the use of the Bluetooth hardware to Nike + iPod applications without using the Bluetooth protocol.

Details of the sub substrate (Click pictures to enlarge)

Q: Why do you think Apple is making things so complicated?

A: I suppose Apple doesn't want Bluetooth to be used with the iPod touch, but I'm not sure why.

At first, I thought the microphone was the reason why Apple didn't allow Bluetooth to be used with the iPod touch. Although the new iPod touch came with a speaker, it still doesn't have a microphone.

When Bluetooth capability is supported, however, voice communication becomes possible with a microphone. Users would also assume that Bluetooth would allow them to use audio headsets.

So, if Bluetooth capability is known to users, many of them will make IP calls with the iPod touch using Skype or other VoIP functions. I suspect that Apple did not advertise the Bluetooth capability of the iPod touch to prevent the users from using it for IP calls. If a lot of users made IP calls through Skype and other services using the new iPod touch's WLAN capability, it would be in competition with the iPhone 3G.

Apple, however, announced a plan to release a headset (with a microphone) that can be used with the iPod touch. It's unknown whether this microphone can be used for Skype and other VoIP services. If it can be used, it means that Apple now allows the iPod touch users to use IP phone services.

In that case, I don't understand why Apple is keeping the Bluetooth function a secret. I'm very curious how the headset will be used when it is actually released.

Q: What about the other new functions?

A: The acceleration sensor was a product of STMicroelectronics, just like the one used in the nano. The iPod touch's other new capabilities include its piezoelectric speaker and volume control buttons.