Texas Instruments CC900DB User manual

SWRU064
User Manual
CC900DB Demonstration Board
Rev. 2.0

SWRU064 2
Table of contents
1 INTRODUCTION.....................................................................................................3
2 CC900DB DEMONSTRATION BOARD...............................................................4
2.1 BEFORE STARTING .................................................................................................4
2.2 DEMONSTRATOR OPERATION.................................................................................4
2.3 SYSTEM PARAMETERS ...........................................................................................5
2.4 CONFIGURATION REGISTER DATA ..........................................................................5
2.5 MICRO-CONTROLLER EEPROM MAPPING.............................................................7
2.6 TROUBLE-SHOOTING..............................................................................................8
3 DEMONSTRATION BOARD SOFTWARE DESCRIPTION.............................9
3.1 SLEEP MODE ..........................................................................................................9
3.2 ACTIVE MODE........................................................................................................ 9
3.3 DATA PACKET DESCRIPTION ..................................................................................9
3.4 DATA PACKET PROTOCOL .................................................................................... 10
3.5 DATA RECEPTION.................................................................................................11
3.6 DATA DECODER ALGORITHM ...............................................................................11
4 DEMONSTRATION BOARD HARDWARE DESCRIPTION .........................12
4.1 RF-SECTION......................................................................................................... 12
4.1.1 The loop filter...............................................................................................12
4.1.2 IF filter......................................................................................................... 12
4.1.3 The modulation input/output........................................................................12
4.1.4 LNA/PA matching ........................................................................................13
4.1.5 The Voltage Controlled Oscillator (VCO)...................................................13
4.1.6 The crystal oscillator ...................................................................................13
4.1.7 The antenna..................................................................................................13
4.2 CONTROLLER SECTION.........................................................................................14
4.2.1 RC oscillator ................................................................................................ 14
4.2.2 Micro-controller I/O .................................................................................... 14
4.2.3 In system programming................................................................................15
4.3 LAYOUT SKETCHES AND CIRCUIT DRAWINGS ....................................................... 16
4.4 CIRCUIT DIAGRAM ...............................................................................................18
4.5 BILL OF MATERIALS............................................................................................. 19
5 USING THE DEMONSTRATOR BOARD AS A PROTOTYPE MODULE...20

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1Introduction
The CC900 single chip RF transceiver includes many features and great flexibility,
which makes the chip suitable for a very large number of applications and system
requirements. The CC900DB Demonstration Board is designed to demonstrate how the
CC900 chip can be used in a simple two-way remote control. Full documentation is
provided for this module, including schematic, layout and micro-controller code, this
design will be a starting point and make it very easy for the user to evaluate transceiver
performance, and in a short time develop his own applications based on this reference
design.
The kit includes two CC900DB Demonstration Boards with a complete CC900
transceiver, micro-controller, integrated PCB antenna and battery. The Demonstration
Boards are pre-programmed to serve as a simple demonstrator. By pushing the “ON”
button, the device will be awakened. Both modules should be awaked before a
transmission takes place. A transmission is initiated by pushing the “TX” button. A
blinking sequence of approximately 2 seconds duration is then transmitted and shown on
the receivers LED. The same “message” is returned from the receiver to the initial
transmitter and shown on its LED as an “acknowledge”. The modules will enter sleep
mode after being left without operation for one minute.
Technical features:
-10 dBm RF power
Up to 30-meter range (depending on antenna orientation)
Small integrated shorted-stub antenna
<1uA power-down current in sleep mode
3.6V Lithium battery supply (~1000mAh)
SmartRF®Studio makes it possible to reconfigure the CC900DB system parameters by
inserting the Demonstration Board into the CC900EB Evaluation Board edge connector.
It is also possible to upgrade the Demonstration Board with new micro-controller
program code from SmartRF®Studio, see the SmartRF®Studio user manual for details.
The CC900DB is also designed to work together with the Atmel AVR micro-controller
STK500 development board, the in-system programmer ATAVRISP or similar. At the
rear side of the board there is a 10 pin connector foot-print which fits a 10-pin ISP cable.
This user manual describes how to use the Demonstration Board and how to use it to
develop your own applications. You will also find a detailed description of the circuit
board and the micro-controller code.
All available documentation can be downloaded from our web site. That includes:
CC900DB User Manual (this document)
CC900DB micro-controller code and configuration data
CC900 data sheet

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2CC900DB Demonstration Board
2.1 Before starting
The CC900DB runs on a 3.6V Lithium battery. If the battery is not mounted and
soldered to the board, insert the battery at the rear side of the board. Observe the LED. If
the LED is turned on continuously, push the “ON” button. For proper operation the LED
shall be pulsing with a period of approximately one second. If not, remove the battery
shortly and reconnect. The battery terminals should be soldered for proper operation.
Important: Be sure not to short-circuit the battery terminals during soldering or at any
point of use.
Before using the CC900DB: The use of radio transceivers is regulated by international
and national rules. Before transmitting a RF signal, please contact your local
telecommunication authorities to check if you are licensed to operate the transceiver.
2.2 Demonstrator operation
The CC900DB demonstrate a very simple two-way remote control system.
To “wake” the module from power-down mode, simply press the “ON” button for a
short time. The LED will then start blinking with a period of approximately 1 second.
This is the “heart-beat” that shows the module is operating. During the short time the
LED is lit, the module is in active receive mode, and listens for a data packet. If a data
packet is not found, it goes to a “rest” mode for approximately 1 second. Hence, the
module listens for a data packet every second. This polled receiver algorithm is
implemented in order to save battery power.
Both modules should be enabled before a successful transmission can take place. A
transmission is initiated by pushing the “TX” button. A data packet of approximately 1.5
second duration is then transmitted. The data packet consists of a long pre-amble and a
short data field. The preamble is longer that 1 second to ensure that the transmission
intercepts with the polled receiver.
The data packet transmitted consists of a blinking sequence of approximately 2 seconds
duration, and will be shown on the receiver’s LED if the data packet was received free
or errors. The same “message” with an acknowledgement flag is then returned from the
receiver to the initial transmitter. Again, the blinking sequence will be shown on the
LED as a receipt acknowledge.

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The modules will enter sleep mode after being left without operation for about one
minute. The CC900 and the micro-controller are then in power-down mode, ensuring
minimum power consumption.
The timing diagram below illustrates a packet transmission sequence when the
transmission is initiated from device number 2.
2.3 System parameters
The system parameters used to generate the configuration data for the CC900DB is
shown below. This is a printout from the SmartRF®Studio software.
System parameters:
X-tal frequency: 12.000000 MHz
X-tal accuracy: +/- 25 ppm
RF frequency: 868.300 MHz
IF stage: 200 kHz
Frequency separation: 40 kHz
Data rate: 1.2 kbps
Power amplifier class: Class AB
RF output power: -10 dBm
Mode: RX
Receiver mode: Optimum sensitivity
LOCK indicator: Continuous
VCO gain: 100
2.4 Configuration register data
Based on the system parameters referred above, the following configuration data is
generated. This is a printout from the SmartRF®Studio software.
DEVICE 1
DEVICE 2
Receiver polling
Devices are active for two
minutes until time-out
Initial
trans-
mission
Message
shown on
receiver LED
LED (ACK)
RX LED TX ACK
TX RX
Ack.
trans-
mission
Acknowledge
shown on
receiver LED
Sleep
mode

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RX mode:
Frame Addr/Data (hex)
A 006A
B 2B0B
C 4841
D 6033
E 8900
F BA00
G CB6C
H E072
TX mode:
Frame Addr/Data (hex)
A 086A
B 2B0B
C 4841
D 608F
E 8914
F BA00
G CB6C
H E072
PD osc. on mode:
Frame Addr/Data (hex)
A 186A
B 2B0B
C 4841
D 6033
E 8900
F BA00
G CB6C
H E072
PD osc. off mode:
Frame Addr/Data (hex)
A 186A
B 2B0B
C 4851
D 6033
E 8900
F BA00
G CB6C
H E042

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RX Precharge mode:
Frame AddrData (hex)
A 006A
B 2B0B
C 4841
D 6033
E 8900
F BA00
G CB6C
H E27A
In this application we have decided to use RX Precharge, RX, TX and PD osc. off
modes. Shown in bold in the listing above is the configuration data that is used, and
stored in the micro-controller EEPROM.
Note: The frame address is combined with the data to get a two-byte word consisting of
the 3 address bits (as MSBs) and the 13 data bits (as LSBs). The combined value is
shown in these listings.
2.5 Micro-controller EEPROM mapping
The CC900 configuration data are stored in the micro-controller EEPROM. The
following map shows the data location. To customise the module for a different
frequency or power level, the EEPROM data can be replaced by new values found using
the SmartRF®Studio software.
EEPROM
Address (hex)
Data (hex) Reference
00 086A TX frame A
02 2B0B TX frame B
04 4841 TX frame C
06 608F TX frame D
08 8914 TX frame E
0A BA00 TX frame F
0C CB6C TX frame G
0E E072 TX frame H
10 E072 RX frame H
12 006A RX PC frame A
14 2B0B RX PC frame B
16 4841 RX PC frame C
18 6033 RX PC frame D
1A 8900 RX PC frame E
1C BA00 RX PC frame F
1E CB6C RX PC frame G
20 E27A RX PC frame H
22 186A PD (osc. Off) frame A
24 4851 PD (osc. Off) frame C

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2.6 Trouble-shooting
If the module does not operate as described in this document, try the following.
Problem Possible solution
LED is continuously on Push the “ON” button once more. If this
does not work, reset the micro-controller
(see below).
LED does not start blinking after “ON” is
pressed
Check battery voltage. If less than 2.7 Volt,
replace battery. Only replace with a battery
of the same type.
If battery voltage is OK, reset the micro-
controller (see below).
Receiver does not receive packet from
closely located transmitter.
Use a Spectrum Analyser at 868.3 MHz to
check the module during transmission.
Connect the analyser to the external antenna
connector foot-print and measure the output
power and frequency using the “max hold”
function. The output power shall be
approximately –10 dBm with a peak at 868,3
MHz +/-10kHz.
Test the receiver the same way in transmit
mode.
The micro-controller can be reset by shorting the reset line to ground for a short
moment. The reset line is located at the edge connector pin 6. Ground is pin 1. The
orientation mark is between pin 2 and 3.

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3Demonstration Board software description
The demonstration board software is implemented in assembly and runs on the Atmel
AVR 8-bit micro-controller ATtiny12L.
The micro-controller handles the CC900 configuration, data encoding and decoding
using Manchester code, and implements a simple packet protocol.
A program listing with the assembly source code is available for reference and can be
used as a starting point for your own applications using the AVR series of controllers
from Atmel.
3.1 Sleep mode
When the CC900DB is left inactive for approximately one minute the CC900 is set to
power down mode, and the controller goes to “sleep”. The controller is awaked by an
interrupt signal at INT1 (pin 6).
In sleep mode the current consumption is less than 1 µA.
3.2 Active mode
In active mode the CC900 is used for receive polling. Once every second the CC900 is
set to RX mode, and the micro-controller starts searching for a preamble. The micro-
controller reads two data bits, if these are not Manchester coded 1’s, the CC900 is set to
power down mode again. The LED is lit during the pre-amble search and will appear as
a “heartbeat” signal.
In active mode the “TX” button input (PB2) is also monitored. If this line is pulled low
by the push button, the micro-controller will configure the CC900 to TX mode, and send
a predefined data packet at the DIO line (PB1), before returning to receiver polling.
3.3 Data packet description
The data packet consists of a pre-amble, a start-of-frame (SOF), and a data field.
The pre-amble is a train of ‘1’s. The train is longer than 1 second in order to ensure that
it intercept with a polled receiver.
The SOF consists of two consecutive ‘0’s. The SOF marks the end of the preamble, and
the start of the actual data.
The data field consists of ID (identification), TYPE (packet type) and DATA (user data,
3 bytes). No FEC (forward error correction) or CRC (cyclic redundancy check) is used
in order to keep it as simple as possible.

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The ID is intended to be used for unique identification of different modules. However,
this is not exploited in this software revision. All modules are addressed using the public
address (0x00).
The TYPE is used to separate between an original message (0x00) and an acknowledge
(0x01).
The 3 DATA bytes are used to code the blinking sequence. Every bit represents a 0.1
seconds period approximately.
No end of packet is implemented.
The data packet is shown in the figure below.
Preamble SOF ID TYPE DATA1 DATA2 DATA3
The figure below shows the symbol coding and an example of a packet with the pre-
amble, data and SOF timing.
Preamble for >1 second SOF
Data field:
ID, TYPE, DATA1,2,3
Preamble (synch symbol):
SOF, start of frame:
Data symbols (Manchester code): 1= 0=
3.4 Data transmission protocol
The data transmission protocol is very simple, only using packet acknowledgement.
When a data package is received without errors, the packet type is checked. If it is an
original message, it is shown on the LED, and an acknowledgement is sent as a reply.
However, if it is an acknowledgement packet that is received, the message is only shown
on the LED without any reply.