RedBoard.
2-Wire Interface
Please note that the SHT15 has a 2-wire interface that is similar to I C but
is
NOT I C
. You may use the SDA and SCL lines to communicate with this
sensor so long as they are connected to A4 and A5 on your Arduino or
Arduino compatible board. You may use any other I/O pins for the Data and
SCK lines as well.
Heads up!
The datasheet states: “The sensor
cannot
be addressed
by I2C protocol; however, the sensor can be connected to an I C bus
without interference with other devices connected to the bus. The
controller must switch between the protocols.” We have experimented
with this with mixed results. Make sure you test extensively if adding
this to an I C bus containing other sensors. Should bus contention be
a problem, simply use two other I/O pins to communicate with the
SHT15.
Multiple Sensors
Unfortunately, the SHT15 has its address hard-coded, making it non-
addressable. As a result, you may not have more than one SHT15 hooked
up to any two pins at a given time. The 2-wire protocol used for this sensor
does not allow for multiple of the same sensor to be on the bus, but it does
allow multiple I C devices to share the same bus as the SHT15, as
mentioned above. In order to use more than one SHT15, you will need to
use a dedicated pin for each sensor’s Data line. You may share the Clock
(SCK) line between multiple sensors. For example, you could have one
sensor’s Data line connected to pin 8 and another connected to pin 7, while
both are sharing pin 9 as the SCK line. Declaring this using the library
mentioned in the next section would look like this:
//Create two instances of the SHT1X sensor
SHT1x sht15(8, 9);//Data, SCK
SHT1x sht15_2(7, 9);//Data, SCK
Pull-up Resistor
As suggested in the datasheet, a 10K
Ω
pull-up resistor was added to the
Data line. Should you find yourself in a situation where you want this sensor
and another I C sensor with pull-up resistors to share the I C lines, you may
cut the trace in between the solder jumper labeled
PU
. If you ever need that
pull-up again, simply place a blob of solder between the two pads.
2
2
2
2
2
2
2
Page 3 of 7
