humidityinterfacemicrocontrollerrenesassensor
I would like to connect the DATA pin of sensor to Digital I/O pin of a microcontroller. I am confused that in the data sheet of the sensor they have mentioned this:
MaxDetect 1-wire bus is used for communication between MCU and RHT03. (MaxDetect 1-wire bus is specially designed by MaxDetect Technology Co., Ltd. , it's different from Maxim/Dallas 1-wire bus, so it's incompatible with Dallas 1-wire bus.)
The one wire bus has the bus passively (i.e. with a resistor) pulled up in the system, and devices communicate on the bus by pulling the bus down. What I would do if I wanted to pull power from the bus is:
You should use a Schottky diode, to minimize the voltage drop. The diode/capacitor combination should make it so that communication can take place (i.e. grounding the bus periodically) without shutting down the MCU. Putting the capacitor after the diode will keep the transitions on the bus data sharp, while keeping the decay of power (voltage) to your MCU gradual. The lower power the device you use is the better to minimize drain on your capacitor, but pretty much any MCU will probably work for you. My preference is Atmel's AVRs, but TI MSP430s and Microchip's PICs are also good candidates for low power consumption.
As shown here, there are two things that can be done.
The Strong Pullup through the Mosfet, should have a appropriately sized Current Limiting Resistor, allowing the tens of milliamps required. If those tens of milliamps are more than your ic's pin can sink, then a secondary in-line resistor (Rt) can be used on the line, for protection.
Best source of information regarding one-wire is of course, Maxim-Dallas's app notes.
Best Answer
When it mentions that in the RHT03 Datasheet it's really just pointing out their protocol is different (Maxim/Dallas is more well known) so if you go searching you'll probably find Maxim 1-wire drivers. But it should interface OK with appropriate code, it just needs a general purpose I/O line. From the datasheet the voltage range is 3.3 - 6 V so either a 3.3 or 5 V microcontroller / supply will be OK.
I've noticed that on the Sparkfun product page for that device they have some sample code available. The code is written in C and for a AT89S52 microcontroller but that should give you a good starting point. The main things will be to work out how to do the equivalent I/O pin control and timing delays for your Renesas device.