Why not build a wireless module to attach on the grill. You could have WLAN or Bluetooth or some other radio standard that fits your needs. This way you'd just have to code some firmware for the module and an app for the phone and connect directly to the grill from the phone.
Cheers /Wes
A very good suggestion!
Connecting directly from the phone to the sensor would skip a lot of infrastructure steps.
However as simple as it sounds, it might actually be more work. By using the existing sensors, applications and infrastructure, I'm limiting the work to configuring existing systems. Your suggestion has a lot of merit, but it might require a lot more software work. I would need to code up an app for the phone. I've not done that before, but it wouldn't be a bad thing to learn how to do.
On the surface, your suggestion does seem simpler.
In fact, if we didn't already have Internet, text messaging, email, your suggestion would clearly be the simplest solution. But connecting a computer to a phone is very simple, all I have to do is write a script to send email to a special email address, and it shows up on my phone as a text message. And any web page can be viewed by my phone, so the infrastructure to the phone already exists.So I don't have to do anything to get that side of things working. My phone came with that capability, as did every computer I use. So I already have a universal communications system at my disposal.
But to address your point on avoiding the wire, I have some zigbee modules that could wirelessly transmit the sensor data, to skip the wire. But the phone would need drivers and an app to talk directly to that, and there is a range problem. The best range my zigbee modules can do without a communications tower is a couple blocks. Not bad, but it won't make it to the grocery store or my office. And I would have to add a zigbee module to the phone. If I use wifi or bluetooth, the range is shorter, and I still must put a computer somewhere to make the sensor talk. I would still need a computer to read and process the temperature data, the wire lets me leave the computer in the office, rather than putting it outside by the grill.
The stoker is a great example of using existing infrastructure to keep things simple. Stoker uses wifi to get to the Internet. From there they use existing infrastructure. The difference between my plan and stoker's is that they use twitter, and I plan to use email and text messaging. It is a difference, but not a huge difference. It is more complex than the path you suggest, but your path would require more work, and may well have a limited range that would reduce usefuleness. My phone's bluetooth has a range of a few dozen feet, my phones wifi has a range of less than 100 feet, and other technologies would require hardware be added to the phone (like zigbee).
my phone can already talk to any internet connect pc. so I had planned to use that path. All I must do is get that PC set-up to control the bbq pit, and communicate what it is doing to the phone. So while it may seem more complex than a direct path from the phone to the grill, it will take less work. The cool thing about the web page is that I can also let the phone send commands to the grill, so I could easily adjust the temperature, or shut the system down. Having the range to communicate to me while I am at work 15 miles away means that I can have the system tell me to come home to fix a problem such as running out of fuel.
So while it seems like my plan is complex, it is simple frim the point of view of the work that is required.
Bur the PID is really the simple solution. The PID is cheap, and is already designed to do the required task. It just isn't as much fun as putting the grill on the Internet.
I actually like the design of the stoker. And the cost is very reasonable. The only reason I would do my own is because I can, and sometimes doing things the hard way is more fun. I can go to a restaurant and buy great bbq that has been in a smoker for 24 hours, one of the best restaurants is only 10 minutes from my house. The reason I would design my own stoker clone, and do the work of operating my own smoker is because it is hard, and because I can. Your suggestion raises the bar a bit and would be harder still... So it does have a lot of merit.