Data Sheet

Bluegiga – A Silicon Labs Company 4

TABLE OF CONTENTS

BT121 overview 6

1.1 Key Features 6

1.2 Typical applications 7

1.3 Block diagram 7

Design guidelines 8

2.1 PCB layout recommendations 8

2.2 Power supply recommendations 8

2.3 Software application related options 8

2.4 Firmware updating related recommendations 8

Pin-out description 10

3.1 Power, ground, reset, RF and boot loader pins 10

3.2 GPIO pins 11

Power control 12

4.1 Power supply requirements 12

4.2 Power saving functionality 12

4.3 Reset 13

4.4 Recovery mode 14

4.5 Clock signals 14

Interfaces 15

5.1 GPIO 15

5.2 UART 16

5.3 I

C 16

5.4 SPI 16

5.5 ADC 16

5.6 DAC 16

5.7 Real-time clock 16

5.8 Microcontroller programming interface 16

Antenna 17

6.1 Effect on antenna matching of a plastic sheet placed near the antenna 18

6.2 Effect on antenna matching of a metal sheet placed under the antenna 19

6.3 Effect on antenna matching of a metal sheet placed against the end of the module 20

6.4 Measured antenna efficiency 21

6.5 Measured 2D radiation patterns 22

6.6 Measured 3D radiation patterns 24

Bluetooth Stack Software 25

Host interface 26