by Steve » 12 Jan 2011, 12:53
The thing with BT is that there has been lots of work in recent years done on ultra low power, low cost BT devices which makes it ideal for a device like this. Unfortunately WiFi is much more expensive to add into a product, partly because the chipsets are more expensive, partly because you need a bit more software (thus more horsepower) to manage it well and mostly becuase you're going to need more juice to power it. (If you want any kind of range)
It's easy to forget that the LiPo battery in your iPhone is an expensive component that's designed to power that big screen GSM/3G radio, ARM chipset, GPS etc etc
The range issue could be addressed with BT using a higher class of device and possibly a tuned antenna but then you get the same problem with power requirements. I'm not that up on current component prices but I imagine with the volumes these guys will be doing and the price point they want to hit, BT is the only viable option.
I think the iPhone SDK also offers some accessory APIs and it probably offers BT serial port as a profile so the iGrill designers were probably able to buy an off-the-shelf BT chipset with stack and then interface it to the temperature sensors with some simple software on a cheap chip.
All this is before we even get into network management, if you look at the way Stokers work over ethernet, they require static IP's (no DHCP) and you need to run them through a switch, so you end up potentially with a lot of setup effort required.
