do anyone help me regarding selecting the sensor, digital temp and humidity in one module and have digital output and one pin connected to micro controller renesas V850 . I have only 3 pins unused. any suggestions please..


1 Answer 1


The DHT22 would work: http://www.adafruit.com/products/385

But with three pins on your MCU you could bit bang yourself an I2C bus to connect many other sensors.

  • \$\begingroup\$ I have 4 digital I/O pins unused and can I apply I2C or SPI protocol with those pins.? if yes how ? or I need another pins? for these types of communication.which communication protocol can I use for DHT22.? \$\endgroup\$ Jun 13, 2014 at 9:18
  • \$\begingroup\$ This is bit banging: en.wikipedia.org/wiki/Bit_banging \$\endgroup\$
    – Dejvid_no1
    Jun 13, 2014 at 9:20
  • \$\begingroup\$ The DHT22 requires no ordinary serial protocol. It uses a pulse timing scheme. Check the datasheet on the page I linked o. \$\endgroup\$
    – Dejvid_no1
    Jun 13, 2014 at 9:21
  • \$\begingroup\$ but I have one more question that already my controller has a lot of applications if I connect 4 DHT22 sensors to the 4 Digital I/O pins and communicate in pulse scheme. does it distrubs any other work done by controller.?? \$\endgroup\$ Jun 13, 2014 at 9:34
  • \$\begingroup\$ You say thanks by selecting my answer... ;) The pulse scheme will probably have an impact on your other code execution. \$\endgroup\$
    – Dejvid_no1
    Jun 13, 2014 at 11:04

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