Swra237b

Application Note AN069

AN069
Low Cost, Long Range One Way Audio
Communications at 900 MHz
By Michael Burns

Keywords

• CC1100 • MSP430
• CC1100E (955 MHz) • Frequency Diversity
• CC1101 • Forward Error Correction (FEC)
• CC1150 • FCC 15.247 Compliance
• Audio

Introduction
This design implements a one way audio The MSP430F2232s 10 bit ADC is used to
link, based on the Texas Instruments sample audio data and Timer A is used in
CC1150 (transmit only), CC1101 PWM (Pulse Width Modulation) mode to
(transmit/receive), and the MSP430F2232 recover the audio from the digital data.
microcontroller. The system consists of a Audio data is sent in ‘packets’; that is, 36
‘transmitter’ card and a ‘receiver’ card, and (‘single Tx’ mode) or 44 (‘double Tx’
operates in the 900 MHz band (868 – 928 mode) ADC samples are collected and
MHz). A power amplifier is included on the sent in a single packet every 4.5 (‘single
transmitter card, to increase the power Tx’ mode) or 5.5 (‘double Tx’ mode)
output to +20 dBm while maintaining msecs.
acceptable harmonic suppression. The
receiver card contains a Low Noise Two transmission techniques will be
Amplifier to increase the receiver described. In ‘single Tx’ mode, each
sensitivity. packet is sent only once. In ‘double Tx’
mode, each packet is sent twice, at two
Note that the design could also be used at different frequencies. ‘Single Tx’ mode
955 MHz by substituting a CC1100E for allows for the use of a lower data rate (150
the CC1150 on the transmitter card and kbps) or for the use of Forward Error
for the CC1101 on the receiver card. Correction (FEC) at a higher data rate
Some modification to the component (300 kbps). It is also possible to increase
values in the PA matching network may the audio sample rate from 8 kHz to 12
also prove necessary. kHz in ‘single Tx’ mode. ‘Double Tx’ offers
increased robustness, but requires the use
The goals for this design were low cost, of a higher data rate (300 kbps) and
and long range. To this end, an external reduced output power due to FCC 15.247
CODEC (COder-DECoder) is not used. restrictions.

SWRA237B Page 1 of 16


Figure 1 – Transmitter

Figure 2 - Receiver



Hardware Description - Transmitter

A CC1150 low power RF transmitter is used, along with a discrete power amplifier using a
BFP450 NPN silicon RF transistor and a BCR400W Active Bias Controller. This amplifier is
capable of producing up to +20 dBm of output power while maintaining harmonic levels more
than 50 dB lower than the fundamental. The microcontroller is a MSP430F2232, operating at
16.384 MHz. The MSP430F2232 includes a built-in 10 bit ADC. The audio path includes a
Programmable Gain Amplifier with gains of 10, 20, 40, and 80, followed by a six pole
Chebychev low pass filter with a cutoff frequency of 3 KHz. Five LEDs are contained on the
card, including a ‘heartbeat’ indicator, along with ‘Locate’ and ‘Cancel Locate’ buttons.

Refer to schematic, Figure 12.

Hardware Description - Receiver

A CC1101 low power RF transceiver is used, along with a discrete low noise RF amplifier
using a BGA2011 NPN RF transistor. A MSP430F2232 microcontroller operating at 16.384
MHz is used. The MSP430F2232 is capable of producing a Pulse Width Modulated audio
signal using a built in timer, eliminating the requirement of an external DAC. This PWM timer
is driven at the full MCU clock frequency (16.384 MHz), twice that required to convert the 10
bit ADC samples into pulses of the required length. This doubles the frequency of the idle
tone from 8 kHz to 16 kHz, making it much easier to remove it from the audio via filtering. The
audio path includes a six pole Chebychev low pass filter with a cut-off frequency of 3 KHz and
a TPA2001D1 One Watt Filter-less Mono Class-D Audio Power Amplifier. A five LED ‘bar
graph’ level indicator is included, along with ‘increase volume’ and ‘decrease volume’ push
buttons. This card can be powered by three 1.2 volt NiCad batteries or 3 AA alkaline
batteries. Battery voltage is monitored using the 10 Bit ADC built into the MSP430F2232. A
blue ‘heartbeat’ LED, an orange ‘packet error’ LED, and a red ‘low battery’ LED are also
included.

Included on both the transmitter and receiver cards is a 2 wire UART interface, intended to
drive a separate 4 line by 20 character LCD display card. This display provides status
information such as RSSI (Received Signal Strength), and the number of packet errors and
lost packets that have occurred.

Refer to schematic, Figure 13.

Software Description – Single Tx mode

Transmitter

Audio is sampled via the MSP430F2232’s 10 bit ADC at an 8 kHz rate (i.e., every 125 usec).
Every 36 ADC samples (4.5 msec), the 36 ten bit audio samples are packed into 45 bytes,
which, together with a status byte, are transmitted to the receiver. One bit of the ‘status’ byte
is used to signal to the receiver to sound the ‘locate’ tone. The ‘locate’ tone is described in the
‘Receiver’ section, below. Since it takes more than 125 usec to pack the data, two buffers are
required; the ‘active’ buffer is used to hold sampled ADC values in ‘real time’, while TX buffer
data is being built from the ‘inactive’ buffer.

Refer to Figure 3, below. ‘GDO0’ is an internally generated signal available at pin 2 of the
CC1150. GDO0 goes high following the transmission of the SYNC bytes, and goes low



following the transmission of the CRC bytes. ‘TX ON’ is generated in software. ‘TX ON’ goes
high when the transmitter is enabled and goes low simultaneously with GDO0.

4500 usec

1493 usec 2667 usec

TX GDO0

TX ON

4160 usec
340 usec

Figure 3 – Transmitter Timing (150 kbps, FEC disabled)

Note that there is a 1493 usec delay from the time that the transmitter is turned on until the
SYNC word has been sent; approximately 810 usec of this is taken up by the PLL calibration
procedure, which is performed prior to every transmission. The preamble and sync bytes take
427 usec to transmit.

Receiver

Data received from the transmitter is ‘played back’ at the same rate at which it was sampled,
i.e., 8 kHz. A data packet is expected every 4.5 milliseconds, which must be unpacked (five
bytes into four 10 bit values). The MSP430F2232’s ‘Timer A’ is used to convert 10 bit audio
samples to PWM (Pulse Width Modulated) signals. Again, it takes much longer than 125 usec
to ‘unpack’ the audio data, so two buffers are required. The receiver must also recognize
when the ‘locate’ button is activated on the Monitor, and substitute a 444 Hz tone pattern for
the ADC sample data. A frequency of 444.4 Hz was chosen because an integer number of
cycles (2) fit into 36 samples.

375 750 1125 1500 1875 2250 2625 3000 3375 3750 4125 0
Frame Timer

1833 usec 2667 usec

TX GDO0
3600 - 3750 usec

RX ON

750 - 900 usec
Sync Time Out

2750 usec

PLL Calibrate
(Packet Received)
721 usec
721 usec

PLL Calibrate
(No SYNC)

Figure 4 – Receiver Timing (‘Paired’ Mode, 150 kbps)

The receiver operates in two modes: ‘paired’ and ‘waiting for beacon’. In ‘waiting for beacon’
mode, the receiver is tuned to the first entry in the ‘frequency hopping’ table, the PLL
calibrated (using automatic calibration mode), and turned on for a maximum period of 125
msec. Once the beacon is detected, the mode is changed to ‘paired’. If the beacon is not
detected in the 125 msec period, the PLL is recalibrated and the process repeated
indefinitely.



In ‘paired’ mode, Timer B of the MSP430F2232 is used as a ‘frame timer’. It is reset and
started once a packet is received (GDO0 goes low), and will automatically reset after 4500
usec. The receiver is tuned to the next channel and PLL calibration initiated immediately
following the reception of a ‘good’ packet. If a packet is successfully received, the data is
unpacked and transferred to the inactive audio data buffer. If a packet is ‘lost’ or contains
errors, the inactive buffer is marked as ‘unusable’ - essentially, all values in the buffer are
replaced with ‘zeros’ during playback. This will mute the audio for 4.5 msec.

In the diagram above, note that the receiver will not be turned on until calibration is complete,
and until the frame timer has reached a value of between 750 and 900 usec (relative to the
end of the last successfully received packet). If SYNC word is not detected once the frame
timer has reached a value of 2750 usec, the receiver is turned off, any data in the receiver’s
FIFO buffer flushed, the receiver is tuned to the next channel, and PLL calibration initiated.

Software Description – Double Tx mode

Transmitter

As in single TX mode, audio is sampled via the MSP430F2232’s 10 bit ADC at an 8 kHz rate
(i.e., every 125 usec). Every 44 ADC samples (5.5 msec), the 44 ten bit audio samples are
packed into 55 bytes, and moved into a TX buffer, e.g. Tx Buffer A. The transmitter is tuned to
the current channel, and data is transmitted from both Tx Buffer A and Tx Buffer B. The
‘current channel’ index is then incremented, so that the next transmission will take place on a
different frequency. During transmission, ADC samples will continue to be collected and
placed in Tx Buffer B. Thus, every ADC sample will be transmitted twice, at two different
frequencies.

5500 usec

TX ON 1320 usec 1900 usec 1900 usec

300 usec 380 usec

TX GDO0 Transmit Buffer A Transmit Buffer B
1620 usec

720 usec 1610 usec 690 usec 1610 usec
220 usec
Transfer Data
from MSP430 to
CC1150 TX FIFO 380 usec 380 usec

570 usec 750 usec

Calibrate PLL

Figure 5 – Transmitter Timing, (300 kbps, double TX)

Note that 380 usec is required to transfer data form the MSP430s RAM into the CC1150s TX
FIFO. However, this time is ‘hidden’, in that the transfer is done simultaneously with PLL
calibration (750 usec).

Receiver

Two data packets are expected every 5.5 milliseconds. The first packet to be received in the
5.5 millisecond time slot (‘Packet A’) is the second transmission of the previous ADC samples
(i.e. Transmit Buffer A). The second packet is the first transmission of the current ADC
samples (i.e. Transmit Buffer B). Once both transmissions of a packet are received, a
decision is made as to which transmission is to be used for playback, based upon the status
of each packet. A packet is not considered to be ‘lost’ unless both transmissions of the packet
were lost (no SYNC word was detected). Similarly, a packet error is considered to have



occurred only if both transmissions of the packet contained errors or if only one packet was
received and it contained a packet error. Packet errors include CRC (Cyclic Redundancy
Check), and address or packet length mismatch.

0 375 750 1125 1500 1875 2250 2625 3000 3375 3750 4125 4500 4875 5250 0 375
Frame Timer


TX Active Transmit Buffer A Transmit Buffer B
167 usec
310 usec
Transfer Data
from CC1101 RX
FIFO to MSP430
760 usec 310 usec

PLL Calibrate
1080 usec 2140 usec 1980usec

RX ON
317 usec 300 usec


RX GDO0 Receive Packet A Receive Packet B

Packet A Sync
Time Out
2195 usec
Packet A Rx
Time Out
3375 usec
Packet B Sync
Time Out
4625 usec
Packet A Rx
Time Out

Figure 6 – Receiver Timing, (300 kbps, double TX)

The timing diagram (above) reveals several points of interest. Note that ‘TX Active’ in this
diagram differs from ‘TX GDO0’ in the previous figure because it includes both the SYNC and
Preamble fields (8 bytes in total). Since the receiver must be active during both the SYNC
and Preamble fields, this more accurately represents the periods of time during which the
receiver must be on. It takes approximately 310 usec to transfer data to and from the
MSP430F2232 and the CC1101CC150 FIFO; it takes approximately 760 usec to calibrate
the frequency synthesizer of the CC1101.

As in single TX mode, the receiver must also recognize when the ‘locate’ button is activated
on the Monitor, and substitute a 363 Hz tone pattern for the ADC sample data. A frequency of
363 Hz was chosen because an integer number of cycles (2) fit into 44 samples.

Synchronization

An additional complication can arise due to the fact that the oscillators on the transmitter and
receiver are not at precisely the same frequency. This causes the received packet to
occasionally arrive too soon or too late; when the software detects that this will happen, a few
of the samples (18) are skipped in order to resynchronize the receiver to the transmitter. See
Figure 5. In this figure, ‘A Valid’ indicates that data in the ‘A’ buffer is valid; similarly, ‘B Valid’
indicates that data in the ‘B’ buffer is valid. A buffer becomes ‘invalid’ while data is being
moved from the RX buffer and unpacked into Buffer A or buffer B – about 200 usec. ‘Using A’
and ‘Using B’ indicate that the receiver is currently ‘playing back’ data in the A or B buffers,
respectively. In the first case (‘Good’), buffer A becomes valid 846 usec before it is used. In
the second case (‘Poor’), the receiver’s oscillator has drifted relative to the transmitter’s, such
that buffer A is received 3.9375 msec before it is used. In the third case (‘Bad’), buffer A is
received 4.7835 msec before it is used. Notice that buffer B now becomes invalid while it is
being used; a ‘Bad’ situation indeed. To correct for this, the software will ‘skip ahead’ 18
samples to reposition the ‘valid’ and ‘using’ timings.



9 msec

A Valid

4.5 msec

B Valid

Using A (Low)
Using B (High)

846 usec (Good)
846 usec (Good)

Using A (Low)
Using B (High)

3.9375 msec (Poor)

3.9375 msec (Poor)

Using A (Low)
Using B (High)

4.7835 msec (Bad)

4.7835 msec (Bad)

B became invalid while in use!

Skip over 18 samples

3.09375 msec (Marginal)

3.09375 msec (Marginal)

A Valid

B Valid

Figure 7 – Receiver Playback Timing

If the status byte indicates that the user has depressed the ‘locate’ button, the receiver’s
audio buffer is filled with values that generate a 444 Hz tone. Additional, all segments of the
LED light bar are flashed at 250 msec rate.

FCC 15.247 Compliance

Basically, there are two approaches to achieving FCC compliance in the 902 – 928 MHz ISM
band:

1) Frequency hopping system: If the 6 dB bandwidth exceeds 250kHz, at least 25
channels must be used, having a duration of less then 0.4 seconds in a 10 second
period, and a maximum output power of 250 mW. The maximum 20 dB bandwidth is
500 kHz. Practically (with the CC1101, CC1150, and CC1110), this can be achieved
using GFSK modulation at a data rate of 175 kbps or less and a deviation of 76.2 kHz
or less. For this application, a data rate of 150 kbps and a deviation of 69.8 kHz are
adequate. Refer to the spectrum plot, Figure 8.



One Way Audio 150 kbps GFSK 69.8 kHz Deviation
-10

-15

-20

-25

-30

-35
bw6dB: 280.0 kHz
bw20dB: 465.0 kHz
-40

-45

-50
902.6 902.8 903 903.2 903.4 903.6 903.8 904 904.2 904.4

Figure 8 – RF Spectrum using GFSK modulation at 150 kbps, 69.8 kHz deviation

Note that for the spectrum plot above, the CC1150 TX card was set to transmit at frequencies
both 1 MHz below (channel 0, 902.5 MHZ) and 1 MHz above (channel 8, 904.5 MHz) the
analyzer’s center frequency (channel 4, 903.5 MHz) . This results in ‘spikes’ in the ‘tails’ of
the distribution.

2) Digital modulation system: Such systems must have a minimum 6 dB bandwidth of
500 kHz, and a maximum output power of 1 W. An additional requirement is that the
peak power spectral density shall not exceed 8 dBm in any 3 kHz band. With the
CC1101, CC1150, and CC1110, this can be achieved by using GFSK modulation at a
data rate of 300 kbps and a deviation setting of 165 kHz. Refer to the spectrum plot,
Figure 9.



One Way 300 kbps GFSK 165 kHz Deviation PO +14 dBm
-15

-20

-25

-30

-35

-40
bw6dB: 542.5 kHz
bw20dB: 882.5 kHz
-45

-50

-55
901.6 901.8 902 902.2 902.4 902.6 902.8 903 903.2 903.4

Figure 9 – RF Spectrum using GFSK modulation at 300 kbps, 165 kHz deviation

When frequency agility (‘double TX’) is implemented, a minimum data rate of 300 kbps is
required. To meet FCC 15.247 specifications, the only choice is to qualify as a ‘digital
modulation system’, using GFSK modulation as shown above.

Recall the FCC restriction that “The peak power spectral density in any 3 kHz bandwidth shall
not exceed +8 dBm”. With the power output set to the full +20 dBm, this restriction is clearly
violated. See Figure 10.

Note: In these plots, the vertical scale (dBm) needs an explanation. A 30 dB attenuator
was used at the input of the spectrum analyzer, to avoid overloading the mixer. The
blue line (-22 dBm) therefore represent a +8 dBm signal, the FCC limit for a spread
spectrum device. The horizontal scale is in MHz.



One Way 300 kbps GFSK 165 kHz Deviation
-15

-20

-25

-30

-35

-40

-45

-50
901.6 901.8 902 902.2 902.4 902.6 902.8 903 903.2 903.4

Figure 10 – RF Spectrum using GFSK modulation at 300 kbps, 165 kHz deviation
+20 dBm Output Power Level

By reducing the output power to +14 dBm, we can meet the FCC restriction:



One Way 300 kbps GFSK 165 KHz Deviation PO +14 dBm
-20

-25

-30

-35

-40

-45

-50

-55
901.6 901.8 902 902.2 902.4 902.6 902.8 903 903.2 903.4

Figure 11 – RF Spectrum using GFSK modulation at 300 kbps, 165 kHz deviation +14
dBm Output Power Level

If frequency agility is not employed (‘single TX’), a data rate of 150 kbps is adequate, and the
frequency hopping table must include a minimum of 25 channels. This will allow the full output
power (+20 dBm) to be used, and the range substantially increased.

Frequency Hopping

Although frequency hopping is implemented in both ‘single Tx’ and ‘double Tx’ modes, the
number of channels in the frequency hopping table differs. In ‘single Tx’ mode, the hopping
table contains 25 channels, spaced 1 MHz apart, and arranged in a pseudo random
sequence. In ‘double Tx mode, frequency hopping is not required, but is done none the less,
to reduce the likelihood of interference from other devices. A set of four channels
(frequencies) is used, on a rotating basis (every transmission is on a different channel). As
written, the four channels used are 0, 20, 40, and 60. The base frequency is set to 902.5 MHz
and the channel spacing to 250 kHz, so channels 0, 20, 40, and 60 correspond to frequencies
of 902.5, 907.5, 912.5, and 917.5 MHz.

When first turned on and after 10 consecutive packets have been lost, the receiver goes into
a ‘waiting for beacon’ mode, continuously listening on the first channel in the ‘frequency
hopping table’ (channel 20 in ‘single Tx’ mode, channel 0 in ‘double Tx’ mode).

Specifications

Frequency Range: 868 to 928 MHz, 256 channels
Transmitter Power: +20 dBm (100 mW) maximum
Data Rate:
150 kbps, FEC disabled, frequency diversity disabled
300 kbps, FEC enabled, frequency diversity disabled
300 kbps, FEC disabled, frequency diversity enabled



Modulation:
150 kbps: GFSK (Gaussian Frequency Shift Keying)
300 kbps: GFSK (Gaussian Frequency Shift Keying)
Audio Sample Rate: 8 kHz (12 kHz possible)
ADC/PWM resolution: 10
Power Consumption – Receiver Card (excluding LEDs):
• Searching for Beacon – 41 mA (135 mW)
• “Paired’ – 33 mA (109 mW)
Power Consumption – Receiver Card (including LEDs):
• Searching for Beacon – 61 mA (201 mW)
• “Paired’ – 50 mA (165 mW)
• Expected Battery Life (3 Alkaline ‘AA’ cells): Approximately 32 hours

Note: The green ‘power on’ LED and orange ‘Lost Packet’ LED consume approximately 8 mA
each; the blue ‘Heartbeat’ LED has an average power consumption of approximately 4 mA.

Power Consumption – Transmitter Card
• Excluding LEDs – 110 mA (550 mW, Vsupply = 5.0 Volts)
• Including LEDs – 123 mA (615 mW, Vsupply = 5.0 Volts)
• Expected Battery Life (3 Alkaline ‘AA’ cells): Approximately 12 hours

Features

• Frequency Hopping: 25 channels pseudo randomly sequenced channels in ‘single Tx’
mode, 4 channels in ‘double Tx’ mode.
• Automatic Gain Control (Monitor/Transmitter): A software controlled AGC is implemented.
The microphone preamplifier has four discrete gain settings of approximately 10, 20, 40,
and 80 (20, 26, 32, and 38 dB), selectable via two control lines. The VGA gain is
increased by 6 dB (2 times) whenever the MSP430’s ADC reads less than 180 codes
(approximately 440 millivolts peak). The VGA gain is decreased by 6 dB (.5 times)
whenever the MSP430’s ADC reads more than 450 codes (approximately 1098 millivolts
peak).
• Manual Volume Control (Receiver): The receiver card uses a Texas Instruments
TPA2001 filter-less class-D audio power amplifier, which features programmable gains of
6, 12, 18, and 23.5 dB. Gain is controlled via two push button switches (‘volume up’ and
‘volume down’), located on the receiver card.
• Sound Level Indicator (Receiver): Five LEDs are arranged to serve as a level indicator.
Each LED (segment) will light for approximately 45 milliseconds (programmable) when
the received ADC codes exceed the following values:

Segment 1: 600 (approximately 215 millivolts peak)

• Locate: Two push buttons (‘Locate’ and ‘Cancel Locate’) are located on the Monitor card.
When activated, the ‘locate’ function will sound a 444 Hz tone at the receiver and blink all
segments of the sound level indicator, at a 250 millisecond rate.

Design Alternatives

The design described herein was optimized for low receiver power consumption and
telephone quality audio. Other optimizations are, of course, possible. For example, by
changing the MSP430s crystal frequency from 16.384 MHz to 12.288 MHz and the cut-off



frequency of the anti-aliasing (Transmitter) and PWM (Receiver) filters from 3000 Hz to 4500
Hz, it is possible to increase the audio bandwidth to 4500 Hz and the sample rate to 12 kHz.
One design goal that was particularly difficult to achieve was the ability to walk with the
receiver in hand without impacting audio quality. The use of FEC (Forward Error Correction)
somewhat improves ‘walking performance’ by reducing the number of CRC errors. However,
FEC is a ‘double rate’ code – that is, redundant information is sent such that the packet can
be reconstructed at the receiving end. This requires that the effective data rate be increased
from 150 kbps to 300 kbps, and the receiver bandwidth be correspondingly increased from to
406 to 650 kHz. This reduces the receiver’s sensitivity. As a result, although the number of
CRC errors is reduced, the number of lost packets (SYNC not detected, address or length
miss-match) increases.

One observation is that errors generally occur in bursts and primarily on only one channel.
This led to the development of ‘double TX’ software, wherein each packet is sent twice, at a
different frequency, a technique labelled ‘frequency diversity’ in some literature. This
technique has shown significant improvements to both range and ‘walking performance’.
However, due to FCC restrictions, the output power in this mode must be reduced to
approximately +14 dBm.

Conclusion

This document describes a set of cards and software that demonstrate telephone quality
audio over a 900 MHz one way link, using the CC1101, CC1150, and MSP430F2232.
Several software alternatives are discussed, including a single transmission of audio samples
(‘single Tx’) and frequency diversity (‘double Tx’; each ADC sample is transmitted twice, at
different frequencies).



+3.3

Ferrite Bead

Ferrite Bead
Monitor (Transmitter)

CC1150
+5.0 +3.3

DVDD AVDD
TPS73033 DGUARD AVDD
DCOUPL AVDD +5.0
4.5 Volts

CSN RF_P Balun Power
GREEN SI
Power On Matching Amplifier
SO
RF_N Network
SCLK
Power Jack
(5 Volts) Rbias
BFP450

XOSC_Q1

XOSC_Q2
BCR400W

26.0 MHz

Active Components:
+3.3 CC1150
MSP430F2232
LMV324
MSP430F2232 LMV321
TS5A3157 (4)
Jumper UCLK TPS73033
Disable AGC SOMI
SIMO
BFP450
P2.0 BCR400W
Jumper
Select External LMV321

+ P2.4/VeREF+
-
LMV324 (3/4)

Programable 6 Pole ORANGE
P4.0
Microphone

Gain Amplifier Chebychev
Low Pass P2.2/ADC_2
Gain = Filter YELLOW
10, 20, 40, 80 fc = 3 KHz P4.1
TS5A3157
LMV324 (1/4) GREEN
TS5A3157 (3) P4.2
PGA Gain 0
P3.6
PGA Gain 1
P3.7
BLUE
RCA P3.0 P1.0
Jack TXD
TO LCD P3.4
Display Card RXD
External Input P3.5
1 VRMS RED
P1.3 P1.1
P1.2
Cancel
Locate

16.384
Locate

MHz LEDS
Orange: Unused
Yellow: Unused
Green: Unused
Blue: Heartbeat
Red: Unused

+3.3

Figure 12 – Transmitter



+3.3

Ferrite Bead

Ferrite Bead
CC1101
DVDD AVDD
Receiver DGUARD AVDD
DCOUPL AVDD
Active Components:
CC1101
MSP430F2232
LMV324
RF_P
TPS76333 Balun BGA2011
Matching LNA
LMV321 Network
RF_N
TPA2001D1 CSN
SI
SO
+5.0 +3.3 SCLK Rbias

XOSC_Q1

XOSC_Q2
TPS76333
4.5 Volts

26.0 MHz

GREEN
Power On

Power Jack
(5 Volts) LED
Level Indicator
MSP430F2232
UCLK P4.0
SOMI
TPA2001D1 LMV824 (3/4) SIMO
P2.0 P4.1
Class D 6 Pole P1.2
Audio Power Chebychev
P4.2
Speaker

Amplifier Low Pass
Filter
fc = 3 KHz
P4.3

Speaker Amp Gain 0 P4.4
P3.6
Speaker Amp Gain 1
P3.7
P3.0 ORANGE
TXD
P3.4 P4.5
RXD
P3.5
TO LCD Battery Voltage Monitor
Display Card P2.2/ADC_2 BLUE
P2.3 P1.0
P2.4
RED
Increase

Decrease
Volume

P1.1
Volume

YELLOW
P2.5

16.384
MHz
LEDS
Orange: Packet Lost
Blue: Heartbeat
+3.3
Red: Low Battery
Yellow: Searching For Beacon

Figure 13 – Receiver



References

General references

[1] CC1101 Data Sheet (Rev. B) (swrs061b.pdf)
[2] CC1150 Single-Chip Low Cost Low Power RF-Transmitter (swrs037.pdf)
[3] Design Note DN006 ‘CC11xx Settings for FCC 15.247 Solutions’
(swra123a.pdf)
[4] MSP430F2232 Mixed Signal Microcontroller (Rev. B) (slas504b.pdf)
[5] BFP450 NPN Silicon RF Transistor(BFP450)
[6] BCR400W Active Bias Controller (BCR400W)
[7] BGA2011 900 MHz MMIC Low Noise Amplifier (BGA2011)
[8] TPA2001 One Watt Filter-less Mono Class D Amplifier(TPA2001)
[9] LMV324 Low-Voltage Rail-to-Rail Output Operational Amplifier (LMV324)
[10] TPS73033 Low Noise High PSRR RF Low Drop Out Regulator (TPS73033)
[11] TPS76333 Low Power Low Dropout Linear Regulator (TPS76333)

Document History
Revision Date Description/Changes
SWRA237A 13 Nov 2008 Initial release
SWRA237B 23 March 2009 Include CC1100E


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TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
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Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Amplifiers amplifier.ti.com Audio www.ti.com/audio
Data Converters dataconverter.ti.com Automotive www.ti.com/automotive
DLP® Products www.dlp.com Broadband www.ti.com/broadband
DSP dsp.ti.com Digital Control www.ti.com/digitalcontrol
Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical
Interface interface.ti.com Military www.ti.com/military
Logic logic.ti.com Optical Networking www.ti.com/opticalnetwork
Power Mgmt power.ti.com Security www.ti.com/security
Microcontrollers microcontroller.ti.com Telephony www.ti.com/telephony
RFID www.ti-rfid.com Video & Imaging www.ti.com/video
RF/IF and ZigBee® Solutions www.ti.com/lprf Wireless www.ti.com/wireless
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2009, Texas Instruments Incorporated

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