Data Sheet

Bluegiga – A Silicon Labs Company 27
Connection examples
The following sections show how to connect a Bluegiga Bluetooth Smart Ready module with various external
devices using the UART, SPI and I
2
C interface.
9.1 Connecting an external host using the UART interface
The connection to an external host is done using the UART interface of the module. This interface is also used
for module reprogramming using the DFU method and thus an optional connector should be provided on the
application PCB to allow reprogramming if needed. A typical solution then is to hold the host in reset state
which will keep the UART pins of the host floating, allowing the interface to be used for programming the
module by using e.g. a PC and suitable software. See Figure 18 .
40
GND
GND
GND
PA7
PA6
PA5
PA4
PB3
PB4
PB5
PB6
PB7
GND
PA11
GND
GND
GND
VDD
PA9
PA10
PA12
PA14
PA13
BOOT0
RESET
GND
VDD
PA10
RESET
BOOT0
PA12
PA9
GND
PB8 PB9
PB10 PB12 PB13 PB14
1
2
3
4
5
6
7
8
9
10
11
12
13
14 15 16 17
18 19
PB15
20
RX
RTS
33
32
31
30
29
28
26
25
24
23
22
21
34
36
38
41
35
37
39
BT121
RESERVED FOR
PRODUCTION PROGRAMMING
TX
TOP VIEW
27
PA11
CTS
BT121
UART
3V3
EXTERNAL HOST
MICROPROCESSOR
3V3
RX
TX
RTS
CTS
VDD
VSS
HOST
UART
GND NC RX TX RTS CTS RST VDD
RESET
3V3
OPTIONAL CONNECTOR ON APPLICATION PCB
ALLOWS CONTROL AND REFLASH OF MODULE
FOR EXAMPLE FROM A PC
Figure 18 Connecting an external host with BT121 using UART