User Manual EE895
Miniature Sensor Module for CO
2
, Temperature and Barometric Pressure | 10
Pin 7 – ISEL (Interface selection)
The EE895 features I
2
C and UART interfaces.
Interface selection:
ISEL logic state
EE895 interface
Low (0…0.9 V)
I
2
C
High (2.1…5.5 V) or not connected
UART
Tab. 2
Interface selection
Serial interface pins:
Pin 8 – TX_SCL
Transmission data / Serial clock
Pin 9 – RX_SDA
Receiving data / Serial data
The function of pins 8 and 9 depends on the interface selected with pin 7 ISEL.
Pin 7 – ISEL connected to ground: EE895 features I
2
C interface:
Pin no. Mode
Comment
8
SCL (serial clock)
External pull-up resistor to V+ (bus high voltage level) is required.
9
SDA (serial data)
External pull-up resistor to V+ (bus high voltage level) is required.
Tab. 3
Pin assignement I
2
C interface
Example:
Fig. 6
Example I
2
C interface
Pin 7 – ISEL connected to V
CC
or left open: EE895 features UART interface:
Pin no. Mode
Comment
8
TX (transmission line)
CMOS compatible (V
OutLowMax
0.4 V; V
OutHighMin
2.6 V)
9
RX (receive line)
CMOS compatible (V
InputLowMax
0.9 V; V
InputHighMin
2.1 V)
Tab. 4
Pin assignment UART interface
