2Wire (unidirectional I2C) coms from blocks of light on an LCD screen via (e.g.) HTML5.

"Here is a crazy idea for interfacing web pages to the real world. Imagine an old SmartPhone sitting in a cradle on a robot or other hardware device. On the phones browser, a web page is pulled up with a Javascript program running that is changing two blocks on the screen from black to white. One block is the clock line, the other is data, and they transmit 2wire (Unidirectional I2C) data. In the cradle, at the bottom of the phones screen, a pair of optical sensors convert the light level into voltages in two wires which then connect to any I2C device (e.g. a servo controller^, D2A, uC, whatever).

Now you have a Javascript controlled robot with wifi connection, maybe camera, screen space for faces or whatever, audio, etc... And optocoupled so there is no danger of frying the phone. No need to root the phone, no need for any apps, no development environment other than a text editor.

The ability to control a robot could then be combined with Javascript based object recognition to turn a cell phone into an object following device.

This is the prototype web page, which I think will work in very minimal browsers please let me know if it works on yours? Thanks!

Type in some data, and hit send. Watch der blinkenlights. Change delay to 10 and send. Change delay to 1 and send. Might be fast enough.

Data:
Delay:
SCL: SDA:

Hardware

The following circuit was developed and tested by Conrad Salinas (THANK YOU!) at delays down to 5:

Bill Of Materials
Part Value Device Package Description
C3 0.1u CAPPTH1 CAP-PTH-5MM Capacitor
R1 PHOTOCELLPTH PHOTOCELLPTH PHOTOCELL CdS photoresistor. This is a low cost way to detect light levels. Resistance decreases with more incoming light. Mfgr Part: GL5528. SparkFun SKU: SEN-09088 (check eBay for better price)
R2 PHOTOCELLPTH PHOTOCELLPTH PHOTOCELL
R3 10K RESISTORPTH-1/2W AXIAL-0.5 Resistor
R4 10K RESISTORPTH-1/2W AXIAL-0.5 Resistor
R5 10K RESISTORPTH-1/2W AXIAL-0.5 Resistor
R6 10K RESISTORPTH-1/2W AXIAL-0.5 Resistor
RV1 10K POTTRIM TRIM_POT
U1 LM339 LM339 TSSOP-14 IC, Quad Comparator. Based on information from the SLCS006N datasheet from TI (www.ti.com).Digikey:296-6607-1-ND LM339PWR

See Also: