Data Sheet

Bluegiga – A Silicon Labs Company 29
9.3 Connecting an external device using I
2
C interface
Bluegiga Bluetooth Smart Ready module BT121 contains two physical I
2
C peripherals (I
2
C 1 and I
2
C 2). I
2
C 1
has two alternatives (Alt 1 and Alt 2) and I
2
C 2 one alternative (Alt 2). All of the three optional configurations
can be used to connect different types of peripheral devices with the module. Pin configurations for the three
I
2
C interface options are listed in Table 2. An example of this type of interfacing is shown in Figure 20 below.
Note the pull-up resistors on the SDA and SCK lines. The example shows the address/chip select lines of the
generic peripherals hardwired to VDD but in practice all or some of them would be wired to GPIO pins of the
BT121 configured to work as chip select or address lines controlled by the application hardware. In the
example below a generic sensor chip is connected to the BT121 using the I
2
C 1 Alt 1 option.
Figure 20 Connecting to an I2C peripheral