Maybe you need pull up resistors? The revision B of the Weather Cape also uses a Sensirion humidity sensor SHT21: http://elinux.org/CircuitCo:BeagleBone_Weather
-Hieu On Tue, Jul 29, 2014 at 9:12 PM, Tatsuya Sasaki <tasas...@gmail.com> wrote: > Hi all. > I hooked up my sensirion SHT20 temp/humid sensor to my BBB. > > http://www.sensirion.com/en/products/humidity-temperature/humidity-sensor-sht20/ > > -SHT20- -BBB- > GND ---> P9-01 > VDD ---> P9-03 > SCL ---> P9-19 > SDA ---> P9-20 > > The datasheet says the address is 01000000 (0x40). > >> 5.3 Sending a Command >> After sending the Start condition, the subsequent I2C >> header consists of the 7-bit I2C device address ‘1000’000’ >> and an SDA direction bit (Read R: ‘1’, Write W: ‘0’). >> The wiring is like the following. > > > I expected to appear the sensor on I2C-1's address 0x40. > But it isn't detected: > > $ sudo i2cdetect -r -y 1 > > 0 1 2 3 4 5 6 7 8 9 a b c d e f > > 00: -- -- -- -- -- -- -- -- -- -- -- -- -- > > 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 50: -- -- -- -- UU UU UU UU -- -- -- -- -- -- -- -- > > 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 70: -- -- -- -- -- -- -- -- > > and also > > $ sudo i2cdetect -r -y 0 > > 0 1 2 3 4 5 6 7 8 9 a b c d e f > > 00: -- -- -- -- -- -- -- -- -- -- -- -- -- > > 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 20: -- -- -- -- UU -- -- -- -- -- -- -- -- -- -- -- > > 30: -- -- -- -- UU -- -- -- -- -- -- -- -- -- -- -- > > 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 50: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- > > 70: UU -- -- -- -- -- -- -- > > I checked the sensor worked as a normal I2C device on my Arduino. > > Do I need to install some drivers on BBB for the sensor? > Or do I missed some procedures? > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
