MICROCHIP MRF49XA-I-ST

MRF49XA
Data Sheet
ISM Band Sub-GHz
RF Transceiver
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C
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© 2009-2011, Microchip Technology Incorporated, Printed in
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Printed on recycled paper.
ISBN: 978-1-61341-846-8
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and manufacture of development systems is ISO 9001:2000 certified.
DS70590C-page 2
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
ISM Band Sub-GHz RF Transceiver
Features
Baseband Features
• Fully Integrated Sub-GHz Transceiver
• Supports Proprietary Sub-GHz Wireless Protocols
• 4-Wire Serial Peripheral Interface (SPI)
Compatible Interface
• CMOS/TTL Compatible I/Os
• Clock and Reset Signals for Microcontroller
• Integrated 10 MHz Oscillator Circuitry
• Integrated Low Battery Voltage Detector
• Supports Power-Saving modes
• Operating Voltage: 2.2V–3.8V
• Low-Current Consumption, Typically:
- 11 mA in RX mode
- 15 mA in TX mode
- 0.3 μA in Sleep mode
• Industrial Temperature Range
• 16-Pin TSSOP Package
• Supports Programmable TX Frequency Deviation
and RX Baseband Bandwidth (BBBW)
• Analog and Digital RSSI Outputs with Dynamic
Range
• RX Synchronous Pattern Recognition
• 16-Bit RX Data FIFO
• Two 8-Bit TX Data Registers
• Low-Power Duty Cycle mode
• Advanced Adjacent Channel Rejection/Blocking
Capability
• Internal Data and Clock Recovery
• Supports Data Filtering
• Data Quality Indicator (DQI)
RF/Analog Features
• Supports ISM Band Sub-GHz Frequency Ranges
(433 MHz, 868 MHz and 915 MHz)
• Modulation Technique: FSK with Frequency
Hopping Spread Spectrum (FHSS) Capability
• Supports High Data Rates:
- Digital mode 115.2 kbps, max.
- Analog mode 256 kbps, max.
• Differential RF Input/Output:
- -110 dBm Typical Sensitivity with 0 dBm
Maximum Input Level
- +7 dBm Typical Transmit Output Power
• High-Resolution Programmable Phase-Locked
Loop (PLL) Synthesizer
• Integrated Power Amplifier
• Integrated Low Phase Noise Voltage Controlled
Oscillator (VCO) Frequency
• Synthesizer and PLL Loop Filter
• Automatic Frequency Control (AFC)
© 2009-2011 Microchip Technology Inc.
Typical Applications
•
•
•
•
•
•
•
•
•
•
•
•
•
Home/Industrial Automation
Remote Control
Wireless PC Peripherals
Remote Keyless Entry
Vehicle Sensor Monitoring
Telemetry
Data Logging Systems
Remote Automatic Meter Reading
Security Systems for Home/Industrial
Environment
Automobile Immobilizers
Sports and Performance Monitoring
Wireless Toy Controls
Medical Applications
Preliminary
DS70590C-page 3
MRF49XA
Pin Diagram: 16-Pin TSSOP
DS70590C-page 4
SDI
1
16
INT/DIO
SCK
2
15
RSSIO
CS
3
14
VDD
SDO
4
13
RFN
MRF49XA
IRQ
5
12
RFP
FSK/DATA/FSEL
6
11
VSS
RCLKOUT/FCAP/FINT
7
10
RESET
CLKOUT
8
9
Preliminary
RFXTL/EXTREF
© 2009-2011 Microchip Technology Inc.
MRF49XA
Table of Contents
1.0 Introduction................................................................................................................................................................................... 7
2.0 Hardware Description................................................................................................................................................................... 9
3.0 Functional Description................................................................................................................................................................ 43
4.0 Application Details...................................................................................................................................................................... 73
5.0 Electrical Characteristics ............................................................................................................................................................ 79
6.0 Packaging Information................................................................................................................................................................ 89
Appendix A: Read Sequence and Packet Structures .......................................................................................................................... 93
Appendix B: Revision History............................................................................................................................................................... 95
The Microchip Web Site ....................................................................................................................................................................... 99
Customer Change Notification Service ................................................................................................................................................ 99
Customer Support ................................................................................................................................................................................ 99
Reader Response .............................................................................................................................................................................. 100
Product Identification System ............................................................................................................................................................ 101
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© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 5
MRF49XA
NOTES:
DS70590C-page 6
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
1.0
INTRODUCTION
Microchip’s MRF49XA is a fully integrated Sub-GHz
RF transceiver. This low-power single chip Frequency
Shift Keying (FSK) baseband transceiver supports:
•
•
•
•
•
•
•
•
Zero-IF architecture
Multi-channel and multi-band
Synthesizer with PLL
Power Amplifier (PA)
Low Noise Amplifier (LNA)
I/Q down converter mixers
I/Q demodulator
Baseband filters (BBFs) and amplifiers
•
•
•
•
•
•
PLL and I/Q VCO with Calibration
Receiver Signal Strength Indicator
Data Quality Indicator
AFC
Baseband Power Amplifier
TX and RX Buffers
The receiver’s Baseband Bandwidth (BBBW) can be
programmed to accommodate various deviations, data
rates and crystal tolerance requirements.
The high-resolution PLL allows:
The simplified functional block diagram of MRF49XA is
shown in Figure 1-1. The MRF49XA is an ideal choice
for low-cost, high-volume, low data rate (<256 kbps),
two-way and short range wireless applications. This
transceiver can be used in the unlicensed 433 MHz,
868 MHz and 915 MHz frequency bands, and for
applications looking for FCC, IC or ETSI certification in
the ISM band.
The MRF49XA has a low phase noise and provides an
excellent adjacent channel interference, Bit Error Rate
(BER) and larger communication coverage along with
higher output power. The MRF49XA device’s AFC
feature allows for the use of a low-accuracy, low-cost
crystal. In order to minimize the total system cost, a
communication link in most of the applications can be
created using a low-cost, generic 10 MHz crystal, a
bypass filter and an affordable microcontroller. The
MRF49XA provides a clock signal for the
microcontroller and avoids the need for a second
crystal on the circuit board. The transceiver can be
interfaced with many popular Microchip PIC®
microcontrollers through a 4-wire SPI, interrupt (IRO)
and Reset. The interface between the microcontroller
and MRF49XA is shown in Figure 1-2.
© 2009-2011 Microchip Technology Inc.
The MRF49XA supports the following digital data
processing features:
• The usage of multiple channels in any of the
bands
• The rapid settling time allows for faster frequency
hopping, bypassing multipath fading and
interference to achieve robust wireless links
The transceiver is integrated with different Sleep modes
and an internal wake-up timer to reduce the overall
current consumption, and to extend the battery life. The
device’s small size with low-power consumption makes
it ideal for various short range radio applications.
Preliminary
DS70590C-page 7
MRF49XA
FIGURE 1-1:
FUNCTIONAL NODE BLOCK DIAGRAM
Antenna
MRF49XA
RF Block
Matching
Circuitry
RFP
PA/LNA
and
PLL/CLK
Block
RFN
Baseband
Amplifier/
Filter/
Limiter
SPI
Signals
Data
Processing
Unit
MCU
Interface
Other
Handshaking
Signals
Power
Management
Memory
10 MHz
FIGURE 1-2:
MICROCONTROLLER TO MRF49XA INTERFACE
PIC® MCU
MRF49XA
I/O/SS
IRO
__
CS
SDO
SDI
SDI
SDO
SCK
SCK
INT
I/O
INT/DIO*
I/O
RESET*
I/O
FSK/DATA/FSEL*
CLKOUT*
OSC1
I/O
RCLKOUT/FCAP/FINT*
* Implies optional signals.
DS70590C-page 8
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
2.0
HARDWARE DESCRIPTION
The MRF49XA is an integrated, single chip ISM Band
Sub-GHz Transceiver. A simplified architectural block
diagram of the MRF49XA is shown in Figure 2-1.
The frequency synthesizer is clocked by an external
10 MHz crystal and generates the 433, 868 and 915
MHz radio frequency. The receiver with a Zero-IF
architecture consists of the following components:
•
•
•
•
•
The quality of the data is checked or validated using the
RSSI and DQI blocks built into the transceiver. Data is
buffered in transmitter registers and receiver FIFOs.
The AFC feature allows the use of a low-accuracy and
low-cost crystal. The CLKOUT is used to clock the
external controller. The transceiver is controlled through
a 4-wire SPI, interrupt (INT/DIO and IRO),
FSK/DATA/FSEL, RCLKOUT/FCAP/FINT and RESET
pins. See Table 2-1 for pin details.
The MRF49XA supports the following feature blocks:
LNA
Down Conversion Mixers
Channel Filters
Baseband Limiting Amplifiers
Receiver Signal Strength Indicator
The transmitter with a direct conversion architecture
has a typical output power of +7 dBm. An internal
transmit/receive switch combines the transmitter and
receiver circuits into differential RFP and RFN pins.
These pins are connected to the impedance matching
circuitry (Balun) and to the external antenna connected
to the device.
•
•
•
•
•
•
Clock Generation
Data Filtering and Amplification
Data Pattern Recognition and Timing
Data Processing and Storage
Independent Transmit and Receiver FIFO Buffers
Registers
These features reduce the processing load, and hence,
allows the use of low-cost 8-bit microcontrollers for data
processing.
The device operates in the low-voltage range of 2.2V–
3.8V, and in Sleep mode, it operates at a very low-current
state, typically 0.3 μA.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 9
MRF49XA ARCHITECTURAL BLOCK DIAGRAM
MIX
I
Cal
AMP Ckt
LNA
RFN
13
RFP
12
7
Self Calibration
MIX
Q
Data Filtering
and Clock
Recovery Unit
I/Q
DEMOD
CLK
DATA
6
Cal
AMP Ckt
FIFO
PA
Preliminary
PLL and I/Q VCO with
Calibration
PA/LNA and PLL/CLK
Block
CLK
OSC
© 2009-2011 Microchip Technology Inc.
CLKOUT
Comparator
DQI
AFC
Baseband Amplifier/Filter/Limiter
Block
WUTM
with
calibration
Data Processing Block
LBDB
Power
Supply Block
Microcontroller Interface Block
Low-Power Block
Clock Block
8
RSSI
9
RFXTL/
EXTREF
15
RSSIO
1
SDI
2
3
4
5
SCK
__
CS
SDO
IRO
10
16
RESET INT/DIO
RCLKOUT/
FCAP/FINT
11
VSS
14
VDD
FSK/DATA/
____
FSEL
MRF49XA
DS70590C-page 10
FIGURE 2-1:
MRF49XA
TABLE 2-1:
Pin
PIN DESCRIPTION
Symbol
Type
1
SDI
Digital Input
Serial data input interface to MRF49XA (SPI input signal).
2
SCK
Digital Input
Serial clock interface (SPI clock).
3
CS
Digital Input
Serial interface chip select (SPI chip/device select).
4
SDO
Digital Output
Serial data output interface from MRF49XA (SPI output
signal).
5
IRO
Digital Output
Interrupt Request Output: Receiver generates an
active-low interrupt request for the microcontroller on the
following events:
• The TXBREG (see Table 2-4) is ready to receive the
next byte.
• The RXFIFOREG (see Table 2-4) has received the
preprogrammed amount of bits.
• RXFIFOREG overflow/TXBREG underrun.
• Negative pulse on interrupt input pin (INT).
• Wake-up timer time-out.
• Supply voltage below the preprogrammed value is
detected.
• Power-on Reset (POR).
6
FSK/DATA/FSEL
Digital Input/Output
Frequency Shift Keying: Transmit FSK data input (with
internal pull-up resistor of 133 kΩ).
Data: When configured as DATA, this pin functions as
follows:
• Data In: Manually modulates the data from the external
host microcontroller when the internal TXBREG is disabled. If the TXBREG is enabled, this pin can be tied
“high” or left unconnected. When reading the internal
RXFIFOREG, this pin must be pulled “low”.
• Data Out: Receives data in conjunction with RCLKOUT
when the internal FIFO is not used.
FIFO Select: Selects the FIFO and the first bit appears on
the next clock when reading the RXFIFOREG. The FSEL pin
has an internal pull-up resistor. This pin must be “high” when
the TX register is enabled. In order to achieve minimum
current consumption, keep this pin “high” in Sleep mode.
7
RCLKOUT/FCAP/
FINT
Digital Input/Output
Recovery Clock Output: Provides the clock recovered from
the incoming data if:
• FTYPE bit of BBFCREG (see Table 2-10) is configured
as digital filter and
• FIFO is disabled by configuring FIFOEN bit of
GENCREG (see Table 2-10)
Filter Capacitor: This pin is a raw baseband data if the
FTYPE bit of BBFCREG is configured as a configuration
filter. The pin can be used by the host microcontroller for data
recovery.
FIFO Interrupt: When the internal FIFO, FIFOEN bit of
GENCREG is enabled, this pin acts as a FIFO full interrupt,
indicating that the FIFO has been filled to its preprogrammed
limit (see FFBC<3:0> bits in FIFORSTREG in Table 2-10).
8
CLKOUT
Digital Output
Clock Output: The transceiver’s clock output can be used by
the host microcontroller as a clock source. Refer Register 2
for more details.
© 2009-2011 Microchip Technology Inc.
Description
Preliminary
DS70590C-page 11
MRF49XA
TABLE 2-1:
PIN DESCRIPTION (CONTINUED)
Pin
Symbol
Type
Description
9
RFXTL/EXTREF
Analog Input
RF Crystal: This pin is connected to a 10 MHz series crystal
or to an external oscillator reference. The crystal is used as a
reference for the PLL which generates the local oscillator
frequency. It is possible to “pull” the crystal to the accurate
frequency by changing the load capacitor value.
External Reference Input: An external reference input, such
as an oscillator, can be connected as a reference source.
Connect the oscillator through a 0.01 μF capacitor.
10
RESET
Digital Input/Output
Active-low hardware pin. This pin has an open-drain Reset
output with internal pull-up and input buffer. Refer to
Section 3.1, Reset for more details.
11
Vss
Ground
12
RFP
RF Input/Output
13
RFN
RF Input/Output
14
VDD
Power
15
RSSIO
Analog Input/Output Received Signal Strength Indicator Output: The analog
RSSI output is used to determine the signal strength. The
response and settling time depends on the external filter
capacitor. Typically, a 4-10 nF capacitor provides optimum
response time for most applications.
16
INT/DIO
Digital Input/Output
DS70590C-page 12
Ground reference.
Differential RF input/output (+).
Differential RF input/output (-).
RF power supply. Bypass with a capacitor close to the pin.
See Section 2.1, Power and Ground Pins for more details.
Interrupt: This pin can be configured as an active-low
external interrupt to the device. If a logic ‘0’ is applied to this
pin, it causes the IRO pin to toggle, signaling an interrupt to
the external microcontroller. The source of interrupt can be
determined by reading the first four bits of STSREG (see
Table 2-4). This pin can be used to wake-up the device from
Sleep.
Data Indicator Output: This pin can be configured to
indicate valid data based on the actual internal settings.
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
2.1
Power and Ground Pins
The power supply bypassing is very essential for better
handling of signal surges and noise in the power line.
The large value decoupling capacitors should be
placed at the PCB power input. The smaller value
decoupling capacitors should be placed at every power
point of the device and at bias points for the RF port.
Poor bypassing leads to conducted interference which
can cause noise and spurious signals to couple into the
RF sections, thereby significantly reducing the
performance.
The VDD pin requires two bypass capacitors to ensure
sufficient bypass and decoupling. However, based on
the selected carrier frequency, the bypass capacitor
values vary. The recommended bypass capacitor
values are listed in Table 2-2 and the type of capacitor
to be used is listed in Table 2-3. The bypass capacitors
are connected to pin 14, as shown in Figure 4-1. The
trace length (VDD pin to bypass capacitors) should be
made as short as possible.
TABLE 2-2:
RECOMMENDED BYPASS
CAPACITORS VALUE
Band
(MHz)
C1(μF)
C2 (nF)
C3 (pF)
433
2.2
10
220
868
2.2
10
47
915
2.2
10
33
TABLE 2-3:
Property
C2
Power-on Reset
Power Glitch Reset
Software Reset
RESET Pin
Software Reset can be issued by sending the
appropriate control command to the device. The result
of the command is similar to POR, but the duration of
the Reset event is much less, typically 0.25 ms. The
Software Reset works only when the Sensitive Reset
mode is selected. See Section 3.1, Reset for details on
Reset; for connection details, see Figure 4-1.
2.3
Power Amplifier
The PA has an open-collector differential output and can
directly drive different PCB antennas, like loop or dipole,
with a programmable output power level during signal
transmission. However, certain types of antennas, like
monopole, need an additional matching circuitry. A
built-in, automatic antenna tuning circuit is used to avoid
the manual tuning and trimming procedures during
production process; the so called “hand effect”.
Low Noise Amplifier
The LNA has approximately 250Ω of differential input
impedance which functions well with the proposed
antenna (PCB/Monopole) during signal transmission.
The LNA, when connected to the 50Ω device, needs an
external matching circuit (Balun) for correct matching
and to minimize the noise figure of the receiver.
C3
SMD Size
A
0603
0603
Dielectric
Tantalum
Ceramic
Ceramic
2.2
•
•
•
•
2.4
RECOMMENDED BYPASS
CAPACITORS
C1
The device enters the Reset mode if any of the
following events take place:
The LNA gain can be selected in four steps for different
gain factors (between 0 dB and -20 dB relative to the
highest gain) based on the required RF signal strength.
This gain selection feature is useful in a noisy
environment.
RESET Pin
An external hardware Reset of MRF49XA can be
performed by asserting the RESET (pin 10) to low.
After releasing the pin, it takes slightly more than
0.25 ms for the transceiver to be released from the
Reset. The pin is driven with an open-drain output, and
hence, it is pulled down while the device is in POR. The
RESET pin has an internal, weak, on-chip, pull-up
resistor. The device will not accept commands during
the Reset period.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 13
MRF49XA
2.5
RFXTL/EXTREF and CLKOUT Pins
The MRF49XA has an internal, integrated crystal
oscillator circuit, and therefore, a single RFXTL/EXTREF
pin is used as a crystal oscillator. The crystal oscillator
circuit, with internal loading capacitors, provides a
10 MHz reference signal for the PLL. The PLL, in turn,
generates the local oscillator frequency. It is possible to
“pull” the crystal to the accurate frequency by changing
the load capacitor value. This reduces the external
component count and simplifies the design. The crystal
load capacitor is programmable from 8.5 pF–16 pF in 0.5
pF steps. Thus, the crystal oscillator circuit can accept a
wide range of crystals from different manufacturers with
different load capacitance requirements. The ability to
vary the load capacitance also helps in fine tuning the
final carrier frequency as the crystal itself is the PLL
reference for the carrier. An external reference input,
such as an oscillator, can be connected as a reference
source. The oscillator can be connected through a 0.01
μF capacitor. Choosing better crystal results in a lesser
TX to RX frequency offset and smaller deviation in
BBBW. Hence, the recommended crystal accuracy
should be ≤40 ppm. Deviation and BBBW are discussed
in detail in Section 2.8, Baseband/Data Filters. The
guidelines for selecting the appropriate crystal are
explained in Section 3.6, Crystal Selection Guidelines.
The transceiver can provide a clock signal through the
Clock Output (CLKOUT) pin to the microcontroller for
accurate timing, and thus, eliminating the need for a
second crystal. This also results in reducing the
component count.
2.6
Phase-Locked Loop
The PLL circuitry determines the operating frequency
of the device. This programmable PLL synthesizer
requires only a single 10 MHz crystal reference source.
The PLL maintains accuracy using the on-chip crystal
controlled reference oscillator and provides maximum
flexibility in performance to the designers. It is possible
to change the crystal to the accurate frequency by
changing the load capacitor value. The RF stability can
be controlled by selecting a crystal with specifications
which satisfy the application and by providing the
functions required to generate the carriers, and by
tuning each of the bands. For more details, see
Section 3.6, Crystal Selection Guidelines. The PLL’s
high resolution allows the use of multiple channels in
any of the bands. The on-chip PLL is able to perform
manual and automatic calibration to compensate for
the changes in temperature or operating voltage.
DS70590C-page 14
2.7
Automatic Frequency Control
The PLL in MRF49XA is capable of performing
automatic fine adjustment for the carrier frequency by
using an integrated AFC feature. The receiver uses the
AFC feature to minimize the frequency offset between
the TX/RX signals in discrete steps, which gives the
advantage of:
• Narrower receiver bandwidth for increased
sensitivity can be achieved
• Higher data rates can be achieved
• Usability of any locally available, low-accuracy
and inexpensive crystals can be used
The MRF49XA can be programmed to automatically
control the frequency or can be manually activated by
a strobe signal.
2.8
Baseband/Data Filters
The BBFs are user-programmable. The receiver
bandwidth can be set by programming the bandwidth of
the BBFs. The receiver, when programmed, is set up
according to the characteristics of the signal to be
received. The baseband receiver has several
programming options to optimize the communication
for a variety of applications. The programmable
functions are as follows:
•
•
•
•
•
Baseband Analog Filter
Baseband Digital Filter
Receive Bandwidth
Receive Data Rate
Clock Recovery
The output data filtering can be performed using either
an external capacitor or a digital filter based on the user
application. The RCLKOUT/FCAP/FINT pin in
MRF49XA provides the raw baseband data if
configured as a configuration filter. It can be used by
the host microcontroller to perform the data recovery.
2.9
Clock Recovery Circuit
The Clock Recovery Circuit (CLKRC) is used to render
a synchronized clock source to recover the data using
an external microcontroller. The CLKRC works by
sampling the preamble on the received data. The
preamble contains a sequence of 1 and 0 for the
CLKRC to properly extract the data timing. In Slow
mode, the CLKRC requires more sampling (12–16
bits), and hence, has a longer settling time before
locking. In Fast mode, it uses less samples (6–8 bits)
before locking, and thereby, the settling time is short
which makes timing accuracy less critical. The
RCLKOUT/FCAP/FINT pin provides the clock
recovered from the incoming data if the baseband filter
is configured as a digital filter.
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
2.10
2.10.1
Data Validity Blocks
2.10.2
RECEIVE SIGNAL STRENGTH
INDICATOR
The MRF49XA provides the RSSI signal to the host
microcontroller, and hence, supports the monitoring of
analog and digital signal strengths. A digital RSSI output
is provided to monitor the input signal level through an
internal STATUS register. The digital RSSI goes high, if
the received signal strength exceeds a given
preprogrammed RSSI threshold level. The digital RSSI
can be monitored by reading the STSREG. Alternatively,
an analog RSSI signal is also available at pin 15
(RSSIO) to determine the signal strength. The analog
RSSI settling time depends on the external filter
capacitor. Typically, a 4–10 nF capacitor provides
optimum response time for most of the applications. See
Section 4.0, Application Details and Section 5.0,
Electrical Characteristics for details on filter capacitors
for analog RSSI. The typical relationship between
analog RSSI voltage and RF input power is graphically
represented in Figure 2-2.
DATA QUALITY INDICATOR
The Data Quality Indicator (DQI) is a special function
which indicates the quality of the received signal and
the link. The unfiltered received data is sampled and
the number of spikes are counted in the received data
for a specified time. If the input signals are of high
value, it indicates the operating FSK transmitter of the
high output signal within the baseband filter bandwidth
from the local oscillator.
2.10.3
DATA INDICATOR OUTPUT
The Data Indicator Output (DIO) is an extension of DQI.
The DIO pin can be configured to indicate valid data
based on the actual internal settings. When an
incoming signal is detected, the DIO uses the DQI
clock recovery lock and digital RSSI signals to
determine the validity of the incoming signal. The DIO
searches for the valid data transitions at an expected
data rate. The desired data rate and the acceptance
criteria for valid data are user-programmable through
the SPI port. The DIO signal is valid when using the
internal receive FIFO or an external pin to capture
baseband data.
The DIO has three modes of operation: Slow, Medium
and Fast. Each mode is dependent on the type of
signals it uses to determine the valid data and the
number of incoming preamble bits present at the
beginning of the packet. The DIO can be multiplexed
with the INT pin for external usage.
ANALOG RSSI VOLTAGE VS. RF INPUT POWER
Analog RSSI Voltage (mV)
FIGURE 2-2:
1150
450
-100
-65
Input Power (dBm)
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 15
MRF49XA
2.11
2.11.1
Power-Saving Blocks
2.12
LOW BATTERY VOLTAGE
DETECTOR
The integrated low-battery voltage detector circuit
monitors the supply voltage against a preprogrammed
value and generates an interrupt on the IRO pin if it falls
below the programmed threshold level. The detector
circuit has a built-in 50 mV hysteresis.
2.11.2
WAKE-UP TIMER
The current consumption of the programmable wake-up
timer is very low, typically 1.5 μA. It is programmable
from 1 ms to several days with an accuracy level of
±10%. The calibration of the wake-up timer takes place
at every start-up and every 30s thereafter, and is
referenced with the crystal oscillator. The calibration is
performed even in Sleep mode. The calibration process
for the wake-up timer takes around 500 μs, and for
proper calibration, the crystal oscillator must be running
before the wake-up timer is enabled.
If any wake-up event occurs, including the wake-up
timer, the wake-up logic generates an interrupt signal
on the IRO pin which can be used to wake-up the
microcontroller and this reduces the period that the
microcontroller needs to be active. If the oscillator
circuit is disabled, the calibration circuit turns it on for a
brief period to perform the calibration in order to
maintain accurate timing before returning to Sleep.
2.11.3
LOW DUTY CYCLE MODE
The MRF49XA can be made to enter into a Low Duty
Cycle mode operation to decrease the average power
consumption in Receive mode. The Low Duty Cycle
mode is normally used in conjunction with the wake-up
timer for its operation. The DCSREG may be
configured so that when the wake-up timer brings the
device out of Sleep mode, the receiver is turned on for
a short time to sample for a signal. Then, the device
returns to Sleep and this process repeats.
DS70590C-page 16
INT, IRO Pins and Interrupts
The Interrupt pin (INT) can be configured as an
active-low external interrupt to MRF49XA which is
provided from the host microcontroller.
The device generates an interrupt request for the host
microcontroller by pulling the IRO pin low if the
following events occur:
• TX register is ready to receive the next byte
• RX FIFO has received the preprogrammed
amount of bits
• FIFO overflow/TX register underrun (TXUROW
overflow in Receive mode and underrun in
Transmit mode)
• Negative pulse on interrupt input pin, INT
• Wake-up timer time-out
• Supply voltage below the preprogrammed value is
detected
• Power-on Reset
The Status bits should be read out to identify the source
of interrupt. The interrupts are cleared by reading the
STATUS register.
See Section 3.9, Interrupts for functional description of
interrupts.
2.13
Transmit Register
The Transmit register in MRF49XA is configured as
two, 8-bit shift registers connected in series to form a
single 16-bit shift register. When the transmitter is
enabled, it starts sending out data from the first register
with respect to the set bit rate. After power-up and with
the Transmit registers enabled, the transmitter
preloads the TX latch with 0xAAAA. This can be used
to generate a preamble before sending actual data.
In hardware, the FSK/DATA/FSEL has two functions:
• As Frequency Shift Keying pin, it basically takes
care of transmitting the FSK data input. The pin
has an internal pull-up resistor of 133 kΩ. This pin
must be “high” when the TX register is enabled to
take care of the transmission.
• As DATA (Data Out), this pin receives the data in
conjunction with RCLKOUT when the internal
FIFO is not used. When reading the internal
RXFIFOREG, this pin must be pulled “low”.
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
2.14
Receive FIFO
The received data in MRF49XA is filled into a 16-bit First
In First Out (FIFO) register. The FIFO is configured to
generate an interrupt after receiving a defined number of
bits. When the internal FIFO is enabled, the FIFO
interrupt pin (RCLKOUT/FCAP/FINT) acts as a FIFO full
interrupt, indicating that the FIFO has been filled to its
preprogrammed limit. The receiver starts filling FIFO
with data when it identifies the synchronous pattern
through the synchronous pattern recognition circuit.
During this process, the FINTDIO bit changes its state.
The FIFO interrupt level is programmable from 1 to 16
bits. It is recommended to set the threshold to at least
half the length of the register (8 bits) to ensure that the
external host microcontroller has time to set up. The
synchronous pattern recognition circuit prevents the
FIFO from being filled up with noise, and hence, avoids
overloading the external host microcontroller.
Note:
The synchronous word is not accessible in
the RX FIFO. The SYNBREG provides this
information to the host microcontroller.
The FIFO read clock (SCK) must be < fXTAL/4 or
< 2.5 MHz for 10 MHz on RFXTAL. The
FSK/DATA/FSEL as the FIFO select pin, selects the
FIFO and the first bit appears on the next clock when
reading the RXFIFOREG.
In hardware, the FSK/DATA/FSEL pin is configured as
DATA (Data In) and with internal TXBREG disabled;
this manually modulates the data from the external host
microcontroller. If the TXBREG is enabled, this pin can
be tied “high” or can be left unconnected.
The internal synchronous pattern and the pattern
length are user-programmable. If the Chip Select (CS)
pin is low, the data bits on the SDI pin are shifted into
the device on the rising edge of the clock on the SCK
pin.The serial interface is initialized if the CS signal is
high.
2.15
Table 5-8. Data is received by the transceiver through
the SDI pin and is clocked on the rising edge of SCK.
The timing diagram is shown in Figure 5-1. MRF49XA
sends out the data through the SDO pin and is clocked
out on the falling edge of SCK. The Most Significant
bit (MSb) is sent first (e.g., bit 15 for a 16-bit command)
in any data. The POR circuit sets default values in all
control and command registers.
Note:
Special care must be taken when the
microcontroller’s built-in hardware serial port
is used. If the port cannot be switched to a
16-bit mode, then a separate I/O line should
be used to control the CS pin to ensure a low
level during the complete duration of the
communication (command) or a software
serial
control
interface
should
be
implemented.
The SDO pin defaults to a low state when the CS pin is
high (the MRF49XA is not selected). This pin has a
tri-state buffer and uses a bus hold logic. For the SPI
interface, see Figure 4-1.
The following parameters can be programmed and set
through SPI:
•
•
•
•
•
•
Frequency band
Center frequency of the synthesizer
Division ratio for the microcontroller clock
Wake-up timer period
Bandwidth of the baseband signal path
Low supply voltage detector threshold
Any of these auxiliary functions can be disabled when
not required. After power-on, all parameters are set to
default values. The programmed values are retained
during Sleep mode. The interface supports the read out
of a status register which provides detailed information
about the status of the transceiver and the received
data.
Note:
Serial Peripheral Interface
The MRF49XA communicates with the host
microcontroller through a 4-wire SPI port as a slave
device. An SPI compatible serial interface lets the user
select, command and monitor the status of the
MRF49XA through the host microcontroller. All registers
consist of a command code, followed by a varying
number of parameter or data bits. As the device uses
word writes, the CS pin should be pulled low for 16 bits.
Data bits on the SDI pin are shifted into the device upon
the rising edge of the clock on the SCK pin whenever the
CS pin is low.
To test the SPI interface lines, set the LBD
(Low Battery Detector) threshold below the
actual VDD and the device must generate
an interrupt.
The maximum clock frequency for the SPI bus is
20 MHz. The MRF49XA supports SPI mode 0,0 which
requires the SCK to remain Idle in a low state. The CS
pin must be held low to enable communication between
the host microcontroller and the MRF49XA. The
device’s timing specification details are given in
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 17
MRF49XA
2.16
Memory Organization
The memory in MRF49XA is implemented as static
RAM and is accessible through the SPI port. Each
memory location functionally addresses a register, control, status or data/FIFO fields, as shown in Table 2-10.
The command/control registers provide control, status
and device address for transceiver operations. The
FIFOs serve as temporary buffers for data transmission
and reception.
code, followed by control, data, status or parameter
bits. The MSb is sent first in all of the commands (e.g.,
bit 15 for a 16-bit command). The POR circuit sets the
default values in all control and command registers.
In general, MRF49XA registers are read only. Hence
the chip status can only be read by the Status Read
Register. During write, only appropriate byte is written
to the desired register. It is not desired to read/write all
registers and there is no way to read back the register.
The commands to the device are sent serially. All
17 commands basically address the 17 registers
affiliated to it. The registers consist of a command
TABLE 2-4:
CONTROL (COMMAND) REGISTER DESCRIPTION
SI. No. Register Name
1
STSREG
2
Register Description
Related Control Functions
Status Read Register
Receive register/FIFO, transmit register,
interrupt, frequency control and signal
strength, POR, wake-up timer, low battery
detect, data quality, clock recovery
GENCREG
General Configuration Register
Frequency band select, enables TX and RX
registers, crystal load capacitor bank value
3
AFCCREG
AFC Configuration Register
AFC locking range, mode, accuracy and
enable
4
TXCREG
Transmit Configuration Register
Modulation polarity, modulation bandwidth,
transmit power and deviation
5
TXBREG
Transmit Byte Register
Transmit data byte
6
CFSREG
Center Frequency Value Set Register
Transmit or receive frequency
7
RXCREG
Receive Control Register
Function of pin 16, DIO mode, RX BBBW,
LNA gain, digital RSSI threshold
8
BBFCREG
Baseband Filter Configuration Register
Clock Recovery mode, data indicator
parameter value and filter type
9
RXFIFOREG
10
FIFORSTREG
11
SYNBREG
Receiver FIFO Read Register
Receive data byte
FIFO and Reset mode Configuration
Register
FIFO interrupt level, FIFO start control and
FIFO enable, POR Sensitivity mode,
synchronous character length
Synchronous Byte Configuration Register
Synchronous character pattern
12
DRSREG
Data Rate Value Set Register
Data rate prescalar set
13
PMCREG
Power Management Configuration Register
Enables receive and transmit chain,
baseband circuit, synthesizer circuit,
oscillator, wake-up timer, low battery detect
and clock out
14
WTSREG
Wake-up Timer Value Set Register
Wake-up timer values for time interval
15
DCSREG
Duty Cycle Value Set Register
Duty Cycle mode and value
16
BCSREG
Battery Threshold Detect and Clock Output
Value Set Register
Low battery detect threshold values and
clock output frequency
17
PLLCREG
PLL Configuration Register
Clock out buffer speed, PLL bandwidth,
dithering and delay
DS70590C-page 18
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
2.17
Control (Command) Register Details
STSREG: STATUS READ REGISTER (POR: 0x0000)(1)
REGISTER 2-1:
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
TXRXFIFO
POR
TXOWRXOF
WUTINT
LCEXINT
LBTD
FIFOEM
ATRSSI
bit 15
bit 8
R-0
R-0
R-0
R-0
DQDO
CLKRL
AFCCT
OFFSV
R-0
R-0
R-0
R-0
OFFSB<3:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15
TXRXFIFO: Transmit Register or Receive FIFO bit
Transmit mode: Transmit Register Ready bit(2)
Indicates whether the transmit register is ready to receive the next byte for transmission.
1 = Ready(5)
0 = Not ready
Receive mode: Receive FIFO Fill (Interrupt) bit(2,3)
Indicates whether the RX FIFO has reached the preprogrammed limit.
1 = Reached the preprogrammed limit(5)
0 = Programming limit has not been reached
bit 14
POR: Power-on Reset bit
1 = POR has occurred(5)
0 = POR has not occured
bit 13
TXOWRXOF: Transmit Overwrite Receive Overflow bit
Transmit mode: Transmit Register Underrun or Overwrite bit
1 = Underrun or overwrite(5)
0 = Operating normally
Receive mode: Receive FIFO Overflow bit
1 = FIFO overflow(5)
0 = Operating normally
bit 12
WUTINT: Wake-up Timer (Interrupt) Overflow bit
1 = Timer overflow has occurred(5)
0 = Operating normally
bit 11
LCEXINT: Logic Change on External Interrupt bit
Indicates a high-to-low logic level change on external interrupt pin (INT/DIO)(5).
1 = High-to-low transition has occurred
0 = High-to-low transition has not occured
Note 1:
2:
3:
4:
5:
All register commands begin with logic ‘1’ and only the STATUS register read command begins with logic ‘0’.
This bit is multiplexed for Transmit or Receive mode.
See the FFBC bits (FIFORSTREG<3:0>) in Register 2-10.
To get accurate values, the AFC should be disabled during the read by clearing the FOFEN bit
(AFCCREG<0>). The AFC offset value (OFFSB bits in the status word) is represented as a two’s
complement number. The actual frequency offset can be calculated as the AFC offset value multiplied by
the current PLL frequency step from CFSREG (FREQB<11:0>).
This bit is cleared after STSREG is read.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 19
MRF49XA
REGISTER 2-1:
STSREG: STATUS READ REGISTER (POR: 0x0000)(1) (CONTINUED)
bit 10
LBTD: Low Battery Threshold Detect bit
Indicates whether the battery or supply voltage is below the preprogrammed threshold limit.
1 = Supply voltage is below threshold
0 = Normal supply voltage feed
bit 9
FIFOEM: FIFO Empty bit
Indicates whether the receive FIFO is empty or filled.
1 = FIFO is empty
0 = FIFO is filled
bit 8
ATRSSI: Antenna Tuning and Received Signal Strength Indicator bit
Transmit mode:
The bit indicates that the antenna tuning circuit has detected a strong RF signal.
1 = Strong RF signal present
0 = Weak or absence of RF signal
Receive mode:
The bit indicates that the incoming RF signal is above the preprogrammed digital RSSI limit.
1 = RF signal is above the threshold value set
0 = RF signal is less than the threshold value set
bit 7
DQDO: Data Quality Detect/Indicate Output bit
Indicates good data quality output.
1 = Quality data is detected
0 = Quality data is unavailable
bit 6
CLKRL: Clock Recovery Lock bit
Indicates clock recovery is locked.
1 = Clock recovery locked
0 = Clock recovery unlocked
bit 5
AFCCT: Automatic Frequency Control Cycle Toggle bit
For each AFC cycle run, this bit toggles between logic ‘1’ and logic ‘0’.
1 = AFC cycle has occurred
0 = No AFC in this cycle
bit 4
OFFSV: Offset Sign Value bit
Indicates the measured difference or frequency offset of any AFC cycle (sign of the offset value).
1 = Higher than the chip frequency
0 = Lower than the chip frequency
bit 3-0
OFFSB<3:0>: Offset bits
The offset value to be added to the frequency control parameter (internal PLL)(4).
1 = Result is negative
0 = Result is positive
Note 1:
2:
3:
4:
5:
Note:
All register commands begin with logic ‘1’ and only the STATUS register read command begins with logic ‘0’.
This bit is multiplexed for Transmit or Receive mode.
See the FFBC bits (FIFORSTREG<3:0>) in Register 2-10.
To get accurate values, the AFC should be disabled during the read by clearing the FOFEN bit
(AFCCREG<0>). The AFC offset value (OFFSB bits in the status word) is represented as a two’s
complement number. The actual frequency offset can be calculated as the AFC offset value multiplied by
the current PLL frequency step from CFSREG (FREQB<11:0>).
This bit is cleared after STSREG is read.
See Appendix A: “Read Sequence and Packet Structures” for the STSREG read sequence.
DS70590C-page 20
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-2:
GENCREG: GENERAL CONFIGURATION REGISTER (POR: 0x8008)
W-1
W-0
W-0
W-0
W-0
W-0
W-0
W-0
CCB<15:8>
bit 15
bit 8
W-0
W-0
TXDEN
FIFOEN
W-0
W-0
W-1
W-0
FBS<1:0>
W-0
W-0
LCS<3:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (10000000b) are serially sent to the microcontroller to identify the bits to be
written in the GENCREG.
bit 7
TXDEN: TX Data Register Enable bit
1 = Internal TX Data register enabled(1)
0 = Internal TX Data register disabled; no transmit
bit 6
FIFOEN: FIFO Enable bit
1 = Internal data FIFO enabled; the FIFO is used to store data during receive(2)
0 = FIFO disabled; FSK/DATA/FSEL and RCLKOUT/FCAP/FINT are used to receive data
bit 5-4
FBS<1:0>: Frequency Band Select bits
These bits set the frequency band to be used in Sub-GHz range.
11 = 915 MHz
10 = 868 MHz
01 = 433 MHz
00 = Reserved
bit 3-0
LCS<3:0>: Load Capacitance Select bits
These bits set and vary the internal load capacitance for the crystal reference.
1111 = 16.0 pF
1110 = 15.5 pF
1101 = 15.0 pF
1100 = 14.5 pF
1011 = 14.0 pF
1010 = 13.5 pF
1001 = 13.0 pF
1000 = 12.5 pF
0111 = 12.0 pF
0110 = 11.5 pF
0101 = 11.0 pF
0100 = 10.5 pF
0011 = 10.0 pF
0010 = 9.5 pF
0001 = 9.0 pF
0000 = 8.5 pF
Note 1:
2:
If the internal TX data register is used, the DATA/FSK/FSEL pin must be pulled “high”.
If the data FIFO is used, the DATA/FSK/FSEL pin must be pulled “low”.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 21
MRF49XA
REGISTER 2-3:
W-1
AFCCREG: AUTOMATIC FREQUENCY CONTROL CONFIGURATION REGISTER
(POR: 0xC4F7)
W-1
W-0
W-0
W-0
W-1
W-0
W-0
CCB<15:8>
bit 15
bit 8
W-1
W-1
AUTOMS<1:0>
W-1
W-1
ARFO<1:0>
W-0
W-1
W-1
W-1
MFCS
HAM
FOREN
FOFEN
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (11000100b) are serially sent to the microcontroller to identify the bits to be
written in the AFCCREG.
bit 7-6
AUTOMS<1:0>: Automatic mode Selection bits (for AFC)
These bits select the operation type (automatic/manual) for performing AFC based on the status of
the MFCS bit.
11 = Keeps offset independent for the state of the DIO signal
10 = Keeps offset only while receiving (DIO = High)
01 = Runs and measures only once after each power-up cycle
00 = Auto mode off (controlled by microcontroller)
bit 5-4
ARFO<1:0>: Allowable Range for Frequency Offset bits
These bits select the offset range allowable between transmitter and receiver frequencies.
11 = +3 FRES to -4 FRES(1)
10 = +7 FRES to -8 FRES
01 = +15 FRES to -16 FRES
00 = No restriction
bit 3
MFCS: Manual Frequency Control Strobe bit
This bit is the strobe signal which initiates the manual frequency control sample to calculate the offset error.
1 = A sample of a received signal is compared with a receiver Local Oscillator (LO) signal and an offset
error is calculated. If bit 1 is enabled, the value is stored in the Offset register of the AFC block.(2)
0 = Ready for the next sample
bit 2
HAM: High-Accuracy (Fine) mode bit(3)
1 = Switches the Frequency Control mode to High-Accuracy mode
0 = Frequency Control mode works in regular mode
bit 1
FOREN: Frequency Offset Register Enable bit
1 = Enables the offset value calculated by the offset sample. The offset value is added to the frequency
control word of the PLL which tunes the desired carrier frequency.
0 = Denies the addition of the offset value to the frequency control word of the PLL
bit 0
FOFEN: Frequency Offset Enable bit
1 = Enables the frequency offset calculation using the AFC circuit
0 = Disables the frequency offset calculation using the AFC circuit
Note 1:
2:
3:
The FRES is the frequency tuning resolution for each band. The FRES for each band is as follows:
433 MHz = 2.5 kHz
868 MHz = 5 kHz
915 MHz = 7.5 kHz
The offset error value is stored in the Offset register (FOREN bit should be enabled) in the AFC block and
is added to the frequency control word of the PLL. Reset this bit before initiating another sample.
In High-Accuracy (Fine) mode, the processing time is twice the regular mode, but the uncertainty of the
measurement is significantly reduced.
DS70590C-page 22
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-4:
W-1
TXCREG: TRANSMIT CONFIGURATION REGISTER (POR: 0x9800)
W-0
W-0
W-1
W-1
W-0
W-0
W-0
CCB<15:9>
MODPLY
bit 15
bit 8
W-0
W-0
W-0
MODBW<3:0>
W-0
W-0
r
W-0
W-0
W-0
OTXPWR<2:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-9
CCB<15:9>: Command Code bits
The command code bits (1001100b) are serially sent to the microcontroller to identify the bits to be
written in the TXCREG.
bit 8
MODPLY: Modulation Polarity bit (for FSK)
When MODPLY is configured as high/low:
1 = Logic ‘0’ is the higher channel frequency and logic ‘1’ is the lower channel frequency (negative
deviation)
0 = Logic ‘0’ is the lower channel frequency and logic ‘1’ is the higher channel frequency (positive
deviation)
bit 7-4
MODBW<3:0>: Modulation Bandwidth bits
These bits set the FSK frequency deviation for transmitting the logic ‘1’ and logic ‘0’(1).
1111 = 240 kHz
1110 = 225 kHz
1101 = 210 kHz
1100 = 195 kHz
1011 = 180 kHz
1010 = 165 kHz
1001 = 150 kHz
1000 = 135 kHz
0111 = 120 kHz
0110 = 105 kHz
0101 = 90 kHz
0100 = 75 kHz
0011 = 60 kHz
0010 = 45 kHz
0001 = 30 kHz
0000 = 15 kHz
bit 3
Reserved: Write as ‘0’
Note 1:
2:
The transmitter FSK modulation parameters are used for calculating the resulting output frequency, as
shown in Equation 2-1.
The output transmit power range is relative to the maximum available power, which depends on the actual
antenna impedance.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 23
MRF49XA
REGISTER 2-4:
TXCREG: TRANSMIT CONFIGURATION REGISTER (POR: 0x9800) (CONTINUED)
OTXPWR<2:0>: Output Transmit Power Range bits(2)
These bits set the transmit output power range. The output power is programmable from 0 dB (Max.)
to -17.5 dB in -2.5 dB steps.
111 = -17.5 dB
110 = -15.0 dB
101 = -12.5 dB
100 = -10.5 dB
011 = -7.5 dB
010 = -5.0 dB
001 = -2.5 dB
000 = 0 dB
bit 2-0
Note 1:
2:
The transmitter FSK modulation parameters are used for calculating the resulting output frequency, as
shown in Equation 2-1.
The output transmit power range is relative to the maximum available power, which depends on the actual
antenna impedance.
EQUATION 2-1:
fFSKOUT = f0 +[(– 1)SIGN x (MB + 1) x (15 kHz)]
where:
f0 is the Channel Center Frequency (see Register 2-6 for f0 Calculation)
MB is the 4-bit Binary Number (MODBW<3:0>)
SIGN = MODPLY XOR FSK
DS70590C-page 24
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-5:
W-1
TXBREG: TRANSMIT BYTE REGISTER (POR: 0xB8AA)
W-0
W-1
W-1
W-1
W-0
W-0
W-0
CCB<15:8>
bit 15
bit 8
W-1
W-0
W-1
W-0
W-1
W-0
W-1
W-0
TXDB<7:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (10111000b) are serially sent to the microcontroller to identify the bits to be
written in the TXBREG.
bit 7-0
TXDB<7:0>: Transmit Data Byte bits
The transmit data bits hold the 8 bits that are to be transmitted. To use this register, set the bit,
TXDEN = 1 (GENCREG<7>). If TXDEN is not set, use the FSK/DATA/FSEL pin to manually modulate
the data.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 25
MRF49XA
REGISTER 2-6:
CFSREG: CENTER FREQUENCY VALUE SET REGISTER (POR: 0xA680)
W-1
W-0
W-1
W-0
W-0
W-1
CCB<15:12>
W-1
W-0
FREQB<11:8>
bit 15
bit 8
W-1
W-0
W-0
W-0
W-0
W-0
W-0
W-0
FREQB<7:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-12
CCB<15:12>: Command Code bits
The command code bits (1010b) are serially sent to the microcontroller to identify the bits to be written
in the CFSREG.
bit 11-0
FREQB<11:0>: Center Frequency Set bits
These bits set the center frequency to be used during transmit or receive. The 12-bit value (FVAL) must
be in a decimal range of 96 to 3903. The value outside this range results in the previous value being
retained and used such that no frequency change occurs(1).
Note 1:
To calculate the center frequency (F0), use Equation 2-2 and the values from Table 2-5. The CFSREG
sets the frequency within the selected band for transmit or receive. Each band has a range of frequencies
available for changing channels or frequency hopping. The selectable frequencies for each band are given
in Table 2-6.
EQUATION 2-2:
F0 = 10 x FA1 x (FA0 + FVAL/4000) MHz
where:
FVAL = Decimal Value of FREQB<11:0> = 96 < FVAL < 3903
Where FA0 and FA1 are constant values as given in Table 2-5 to calculate the Center Frequency.
TABLE 2-5:
CENTER FREQUENCY VALUE
Range
FA1
FA0
433 MHz
1
43
868 MHz
2
43
915 MHz
3
30
TABLE 2-6:
FREQUENCY BAND TUNING RESOLUTION
Frequency Band (MHz)
Min. (MHz)
Max. (MHz)
Tuning Resolution (kHz)
400
430.2400
439.7575
2.5
800
860.4800
879.5150
5.0
900
900.7200
929.2725
7.5
DS70590C-page 26
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-7:
W-1
RXCREG: RECEIVE CONTROL REGISTER (POR: 0x9080)
W-0
W-0
W-1
W-0
CCB<15:11>
W-0
W-0
FINTDIO
W-0
DIORT<1:0>
bit 15
bit 8
W-1
W-0
W-0
RXBW<2:0>
W-0
W-0
RXLNA<1:0>
W-0
W-0
W-0
DRSSIT<2:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-11
CCB<15:11>: Command Code bits
The command code bits (10010b) are serially sent to the microcontroller to identify the bits to be
written in the RXCREG.
bit 10
FINTDIO: Function Interrupt/Data Indicator Output bit
Sets the pin 16 function as the DIO or interrupt.
1 = DIO output
0 = INT input
bit 9-8
DIORT<1:0>: Data Indicator Output Response Time bits
If pin 16 is selected as DIO, these bits set the response time within which the transceiver detects and
indicates the incoming synchronous bit pattern, and issues an interrupt to the host microcontroller.
11 = Continuous
10 = Slow
01 = Medium
00 = Fast
bit 7-5
RXBW<2:0>: Receiver Baseband Bandwidth bits
These bits set the bandwidth of demodulated data. The bandwidth can accommodate different data
rates and deviations during frequency keying.
111 = Reserved
110 = 67 kHz
101 = 134 kHz
100 = 200 kHz
011 = 270 kHz
010 = 340 kHz
001 = 400 kHz
000 = Reserved
bit 4-3
RXLNA<1:0>: Receiver LNA Gain bits
These bits, when set to different values, can accommodate environments with high interferences. The
LNA gain also affects the true RSSI value.
11 = -20 dB
10 = -14 dB
01 = -6 dB
00 = 0 dB
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 27
MRF49XA
REGISTER 2-7:
bit 2-0
RXCREG: RECEIVE CONTROL REGISTER (POR: 0x9080) (CONTINUED)
DRSSIT<2:0>: Digital RSSI Threshold bits
These bits can be set to indicate the incoming signal strength above a preset limit. The result enables
or disables the DQDO bit (STSREG<7>).
111 = Reserved
110 = Reserved
101 = -73 dB
100 = -79 dB
011 = -85 dB
010 = -91 dB
001 = -97 dB
000 = -103 dB
DS70590C-page 28
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-8:
W-1
BBFCREG: BASEBAND FILTER CONFIGURATION REGISTER (POR: 0xC22C)
W-1
W-0
W-0
W-0
W-0
W-1
W-0
CCB<15:8>
bit 15
bit 8
W-0
W-0
W-1
W-0
W-1
ACRLC
MCRLC
r
FTYPE
r
W-1
W-0
W-0
DQTI<2:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (11000010b) are serially sent to the microcontroller to identify the bits to be
written in the BBFCREG.
bit 7
ACRLC: Automatic Clock Recovery Lock Control bit
1 = Configures the clock recovery lock control as automatic. In this setting, the clock recovery starts
in Fast mode and automatically switches to Slow mode after locking
0 = Clock recovery lock is controlled in Manual mode
bit 6
MCRLC: Manual Clock Recovery Lock Control bit
1 = Configures the clock recovery lock control to Fast mode. Fast mode requires a preamble of at least
6-8 bits to determine the clock rate and then it locks.
0 = Configures the clock recovery lock control to Slow mode. Slow mode takes a bit longer period and
requires a preamble of at least 12-16 bits to determine the clock rate and then it locks. Slow mode
requires more accurate bit timing. See Register 2-12 for the relationship between data rate and
clock recovery.
bit 5
Reserved: Write as ‘1’
bit 4
FTYPE: Filter Type bit
1 = Configures the baseband filter as an analog RC low-pass filter
0 = Configures the baseband filter as a digital filter(1)
bit 3
Reserved: Write as ‘1’
bit 2-0
DQTI<2:0>: Data Quality Threshold Indicator bits
The threshold parameter for the DQI should be set to less than four to report good signal quality if the
bit rate is close to the deviation. Usually, if the data rate falls less than the deviation, a higher threshold
parameter is permitted and might report a good signal quality(2).
Note 1:
2:
The digital filter is a digital version of a simple RC low-pass filter followed by a comparator with hysteresis.
The time constant for the digital filter is automatically calculated based on the bit rate set in the DRSREG.
The bit rate in this mode should not exceed 115 kbps. In analog RC filter, the demodulator output is fed to
the RCLKOUT/FCAP/FINT pin over a 10 kΩ resistor. The filter cutoff frequency is set by the external
capacitor connected to this pin and VSS. Table 2-6 shows the optimum filter capacitor values for different
data rates.
The DQI parameter is calculated using Equation 2-3. The DQI parameter in BBFCREG should be chosen
according to the following rules:
- The parameter should be > 4, otherwise, noise might be treated as a valid FSK signal.
- The maximum value is 7.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 29
MRF49XA
EQUATION 2-3:
TABLE 2-7:
DQIpar = 4 x (Deviation – TX/RXoffset)/Bit Rate
DS70590C-page 30
DATA RATE VS. FILTER
CAPACITOR VALUE
Data Rate
Preliminary
Filter Capacitor Value
1.2 kbps
12 nF
2.4 kbps
8.2 nF
4.8 kbps
6.8 nF
9.6 kbps
3.3 nF
19.2 kbps
1.5 nF
38.4 kbps
680 pF
57.6 kbps
270 pF
115.2 kbps
150 pF
256 kbps
100 pF
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-9:
W-1
RXFIFOREG: RECEIVER FIFO READ REGISTER (POR: 0xB000)
W-0
W-1
W-1
W-0
W-0
W-0
W-0
CCB<15:8>
bit 15
bit 8
W-0
W-0
W-0
W-0
W-0
W-0
W-0
W-0
RXDB<7:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (10110000b) are serially sent to the microcontroller to identify the bits to be
written in the RXFIFOREG.
bit 7-0
RXDB<7:0>: Receiver Data Byte bits
These are the recovered data bits stored in the FIFO. The controller can read 8 bits from the receiver
FIFO over the SPI bus. The FIFOEN bit (GENCREG<6>) should be set to receive these bits.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 31
MRF49XA
REGISTER 2-10:
W-1
FIFORSTREG: FIFO AND RESET MODE CONFIGURATION REGISTER
(POR: 0xCA80)
W-1
W-0
W-0
W-1
W-0
W-1
W-0
CCB<15:8>
bit 15
bit 8
W-1
W-0
W-0
FFBC<3:0>
W-0
W-0
W-0
W-0
W-0
SYCHLEN
FFSC
FSCF
DRSTM
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (11001010b) are serially sent to the microcontroller to identify the bits to be
written in the FIFORSTREG.
bit 7-4
FFBC<3:0>: FIFO Fill Bit Count bits
Sets the received bits before generating an external interrupt to the host microcontroller to indicate the
receive FIFO is ready to be read. The maximum fill level is 15(1).
bit 3
SYCHLEN: Synchronous Character Length bit
This bit sets the synchronous character length to byte or word long.(2)
1 = Byte long. User-programmable SCL0 byte is used.
0 = Word long. The character is composed of the SCL1 and SCL0 bytes. The SCL1 byte value is fixed
and is not configurable. The SCL0 byte value is user-programmable through the SYNBREG.
bit 2
FFSC: FIFO Fill Start Condition bit
This bit sets the condition at which the FIFO starts filling with data.
1 = The FIFO will continuously fill irrespective of noise or good data
0 = The FIFO will fill when it recognizes the synchronous character pattern as defined internally
bit 1
FSCF: FIFO Synchronous Character Fill bit
1 = The FIFO starts filling with data when it detects the synchronous character pattern as defined in
the FFSC bit
0 = The FIFO fill stops
To restart the synchronous character pattern recognition, just clear and set this bit(2).
bit 0
DRSTM: Disable (Sensitive) Reset mode bit
1 = Disables(3)
0 = Enables System Reset for any glitches above 0.2V in the power supply
Note 1:
2:
3:
On register overrun, the data will be lost. Therefore, the developer must take into account the processing
time required to read-out data before a register overrun. It is recommended to set the fill value to half of
the desired number of bits to be read to ensure sufficient time for additional processing. See Register 2-1
for the description of the TXRXFIFO and TXUROW bits, and Register 2-9 for details on polling and
interrupt driven FIFO reads from the SPI bus.
For synchronous character length selection, see Table 2-8.
For Reset mode selection, see Table 2-9.
DS70590C-page 32
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
TABLE 2-8:
SYNCHRONOUS CHARACTER SELECTION
SYCHLEN
SCL0
Synchronous Character
1
NA
0xD4
0xD4 (byte long)
0
0x2D
0xD4
0x2DD4 (word long)
TABLE 2-9:
RESET MODE SELECTION
DRSTM
Note:
SCL1
Reset mode
1
Normal Reset
0
Sensitive Reset
Condition
Reset is triggered when VDD is below 250 mV
Reset is triggered when VDD is below 1.6V and VDD glitch
is greater than 600 mV
See Appendix A: “Read Sequence and Packet Structures” for FIFO packet structures.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 33
MRF49XA
REGISTER 2-11:
W-1
SYNBREG: SYNCHRONOUS BYTE CONFIGURATION REGISTER
(POR: 0xCED4)
W-1
W-0
W-0
W-1
W-1
W-1
W-0
CCB<15:8>
bit 15
bit 8
W-1
W-1
W-0
W-1
W-0
W-1
W-0
W-0
SYNCB<7:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (11001110b) are serially sent to the microcontroller to identify the bits to be
written in the SYNBREG.
bit 7-0
SYNCB<7:0>: Synch Byte Configuration bits
The SYNBREG assigns the value to SCL0 of the synchronous character in the FIFORSTREG. The
value is valid for a byte or word long synchronous character.
DS70590C-page 34
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-12:
W-1
DRSREG: DATA RATE VALUE SET REGISTER (POR: 0xC623)
W-1
W-0
W-0
W-0
W-1
W-1
W-0
CCB<15:8>
bit 15
bit 8
W-0
W-0
W-1
W-0
W-0
W-0
W-1
W-1
DRPV<6:0>(1)
DRPE
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (11000110b) are serially sent to the microcontroller to identify the bits to be
written in the DRSREG.
bit 7
DRPE: Date Rate Prescaler Enable bit
1 = Enables the prescaler to obtain smaller values of expected data rates. The prescaler value when
enabled is approximately 1/8 of the actual data rate.
0 = Disables the prescaler
bit 6-0
DRPV<6:0>: Data Rate Parameter Value bits(1)
These bits represent the decimal value of the 7-bit parameter which is used to calculate the expected
data rate.
Note 1:
To calculate the expected data rate, use Equation 2-4. To calculate the DRPV<6:0> decimal value for a given
bit rate, use Equation 2-5. If the prescaler is not used, the data rates range from 2.694 kbps–344.828 kbps.
With the prescaler enabled, the data rates range from 337 bps to 43.103 kbps. The Slow Clock Recovery
mode requires more accurate bit timing when setting the data rate. Equation 2-6 is used to calculate the data
rate accuracy for Fast and Slow modes.
EQUATION 2-4:
DREx (kbps) = 10000/[29 x (DRPV<6:0> + 1) x (1 + DRPE x 7)]
where:
DRPV<6:0> is the Decimal Value from 0 to 127 and the Prescaler (DRPE) is ‘1’ (if ON) or ‘0’ (if OFF).
EQUATION 2-5:
DRPV<6:0> = 10000/[29 x (1 + DRPE x 7) x DREx] – 1
where:
DREx is the Expected Data Rate.
EQUATION 2-6:
• Slow mode Accuracy (SMA) = ΔDR/DR < 1/(29 x LN)
• Fast mode Accuracy (FMA) = ΔDR/DR < 3/(29 x LN)
where:
LN is the longest number of expected 1’s or 0’s in the data stream.
ΔDR is the difference in the actual data rate versus the set data rate in the transmitter.
DR is the expected data rate set using DRPV<6:0>.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 35
MRF49XA
REGISTER 2-13:
W-1
PMCREG: POWER MANAGEMENT CONFIGURATION REGISTER
(POR: 0x8208)
W-0
W-0
W-0
W-0
W-0
W-1
W-0
CCB<15:8>
bit 15
bit 8
W-0
W-0
RXCEN
BBCEN(1)
W-0
TXCEN
W-0
SYNEN
W-1
OSCEN
W-0
LBDEN
W-0
W-0
(3)
WUTEN
CLKOEN
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (10000010b) are serially sent to the microcontroller to identify the bits to be
written in the PMCREG.
bit 7
RXCEN: Receiver Chain Enable bit
The receiver chain consists of a baseband circuit, synthesizer and crystal oscillator.
1 = Enables receiver chain
0 = Disables receiver chain
bit 6
BBCEN: Baseband Circuit Enable bit(1)
The baseband circuit, synthesizer and oscillator work together to demodulate and recover the data
transmitted to the synthesizer (SYNEN bit). The OSCEN bit must be enabled along with the baseband
circuits in order to receive data.
1 = Enables baseband circuit
0 = Disables baseband circuit
bit 5
TXCEN: Transmit Chain Enable bit
The transmit chain consists of power amplifier, synthesizer, oscillator and transmit register.
1 = Enables the transmitter chain and starts transmission (if the TX register is enabled)
0 = Disables transmitter chain
bit 4
SYNEN: Synthesizer Enable bit
The synthesizer consists of a PLL, oscillator and VCO for controlling the channel frequency.
1 = Enables the synthesizer
0 = Disables the synthesizer
bit 3
OSCEN: Crystal Oscillator Enable bit
1 = Enables the crystal oscillator
0 = Disables the crystal oscillator
bit 2
LBDEN: Low Battery Detector Enable bit
The battery detector can be programmed to 32 different threshold levels(2).
1 = Enables the battery voltage detector circuit
0 = Disables the battery voltage detector circuit
bit 1
WUTEN: Wake-up Timer Enable bit(3)
1 = Enables the wake-up timer circuit
0 = Disables the wake-up timer circuit
Note 1:
2:
3:
4:
This bit can be disabled to reduce current consumption.
See BCSREG (Register 2-16) for programming details.
See WTSREG (Register 2-14) for details on programming the wake-up timer value.
If the CLKOEN bit is cleared by enabling the clock output, the oscillator continues to run even if the
OSCEN bit is cleared. The device will not fully enter into the Sleep mode.
DS70590C-page 36
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-13:
bit 0
Note 1:
2:
3:
4:
PMCREG: POWER MANAGEMENT CONFIGURATION REGISTER
(POR: 0x8208) (CONTINUED)
CLKOEN: Clock Output Enable bit
On-chip Reset or power-up clock output is enabled so that a processor can execute any special setup
sequences as required by the designer(2).
1 = Disables the clock output
0 = Enables the clock output(4)
This bit can be disabled to reduce current consumption.
See BCSREG (Register 2-16) for programming details.
See WTSREG (Register 2-14) for details on programming the wake-up timer value.
If the CLKOEN bit is cleared by enabling the clock output, the oscillator continues to run even if the
OSCEN bit is cleared. The device will not fully enter into the Sleep mode.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 37
MRF49XA
REGISTER 2-14:
W-1
WTSREG: WAKE-UP TIMER VALUE SET REGISTER (POR: 0xE196)
W-1
W-1
W-0
W-0
CCB<15:13>
W-0
W-0
W-1
WTEV<4:0>
bit 15
bit 8
W-1
W-0
W-0
W-1
W-0
W-1
W-1
W-0
WTMV<7:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-13
CCB<15:13>: Command Code bits
The command code bits (111b) are serially sent to the microcontroller to identify the bits to be written
in the WTSREG.
bit 12-8
WTEV<4:0>: Wake-up Timer Exponential Value bits
These bits define the exponential value to be used to set up the time interval. The value must be a
decimal equivalent between 0 and 29(1).
bit 7-0
WTMV<7:0>: Wake-up Timer Multiplier Exponential Value bits
These bits define the multiplier value to be used to set up the time interval. The value must be a
decimal equivalent between 0 and 255(1).
Note 1:
The WTSREG sets the wake-up interval for the device. After setting the wake-up time, the WUTEN bit
(PMCREG<1>) must be cleared and set at the end of every wake-up cycle. The wake-up duration can be
calculated using Equation 2-7.
EQUATION 2-7:
WUTIME (ms) =[1.03 x WTMV<7:0> x 2WTEV<4:0>] + 0.5 ms
where:
WTMV<7:0> = Decimal Value between 0 to 255
WTEV<4:0> = Decimal Value between 0 to 29
DS70590C-page 38
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-15:
W-1
DCSREG: DUTY CYCLE VALUE SET REGISTER (POR: 0xC80E)
W-1
W-0
W-0
W-1
W-0
W-0
W-0
CCB<15:8>
bit 15
bit 8
W-0
W-0
W-0
W-0
W-1
W-1
W-1
DCMV<6:0>
W-0
DCMEN
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (11001000b) are serially sent to the microcontroller to identify the bits to be
written in the DCSREG.
bit 7-1
DCMV<6:0>: Duty Cycle Multiplier Value bits
These bits are used to calculate the duty cycle or on time of the receiver after the wake-up timer has
brought the MRF49XA out of Sleep mode(1).
bit 0
DCMEN: Duty Cycle mode Enable bit
1 = Enables the Duty Cycle mode
0 = Disables the Duty Cycle mode
Note 1:
For operation in Duty Cycle mode, the receiver must be disabled (RXCEN = 0) and the wake-up timer
must be enabled (WUTEN = 1) in PMCREG. The registers, DCSREG and WTSREG, can be used to
reduce the current consumption of the receiver. The DCSREG can be set up so that when the wake-up
timer brings the MRF49XA out of Sleep mode, the receiver is turned on for a short period to sample the
signal presence before returning to Sleep. The process in the Duty Cycle mode starts over. The duty cycle
uses the multiplier value of the wake-up timer, in parts for its calculation, as shown in Equation 2-8.
EQUATION 2-8:
DC = [(DCMV<7:1> x 2 + 1)]/[WTMV<7:0> x 100%]
where:
WTMV is WTMV<7:0> bits of the WTSREG.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 39
MRF49XA
REGISTER 2-16:
W-1
BCSREG: BATTERY THRESHOLD DETECT AND CLOCK OUTPUT VALUE SET
REGISTER (POR: 0xC000)
W-1
W-0
W-0
W-0
W-0
W-0
W-0
CCB<15:8>
bit 15
bit 8
W-0
W-0
W-0
COFSB<2:0>
W-0
W-0
r
W-0
W-0
W-0
LBDVB<3:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (11000000b) are serially sent to the microcontroller to identify the bits to be
written in the BCSREG.
bit 7-5
COFSB<2:0>: Clock Output Frequency Set bits
These bits set the output clock frequency which can be used to run an external host microcontroller.
111 = 10 MHz
110 = 5 MHz
101 = 3.33 MHz
100 = 2.5 MHz
011 = 2 MHz
010 = 1.66 MHz
001 = 1.25 MHz
000 = 1 MHz
bit 4
Reserved: Write as ‘0’
bit 3-0
LBDVB<3:0>: Low Battery Detect Value bits
These bits set the decimal value to calculate the battery detect threshold voltage level(1,2).
Note 1:
2:
When the battery level goes down by 50 mV below this value, the LBTD bit (STSREG<10>) is set, indicating
that the battery level is below the programmed threshold. This is useful in monitoring discharge-sensitive
batteries, such as Lithium cells. The low battery detect can be enabled by setting the LBDEN bit
(PMCREG<2>) and can be disabled by clearing the bit.
The low battery threshold value is programmable from 2.2V – 3.8V by using Equation 2-9.
EQUATION 2-9:
Threshold Voltage Value = 2.25 +[0.1 x (LBDVB<3:0>)]
where:
LBDVB<3:0> is the Decimal Value from 0 to 15.
DS70590C-page 40
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
REGISTER 2-17:
W-1
PLLCREG: PLL CONFIGURATION REGISTER (POR: 0xCC77)
W-1
W-0
W-0
W-1
W-1
W-0
W-0
CCB<15:8>
bit 15
bit 8
W-0
W-1
—
W-1
W-1
W-0
W-1
W-1
W-1
r
PDDS
PLLDD
r
PLLBWB
CBTC<1:0>
bit 7
bit 0
Legend:
r = reserved bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-8
CCB<15:8>: Command Code bits
The command code bits (11001100b) are serially sent to the microcontroller to identify the bits to be
written in the PLLCREG.
bit 7
Unimplemented: Write as ‘0’
bit 6-5
CBTC<1:0>: Clock Buffer Time Control bits
These bits control the rise and fall time for the clock buffer which is dependant on the output clock
frequency from the BCSREG.
11 = 5 MHz - 10 MHz
10 = 3.3 MHz
01 = 2.5 MHz or less
00 = 2.5 MHz or less
bit 4
Reserved: Masked to ‘1’
bit 3
PDDS: Phase Detector Delay Switch bit
1 = Enables the phase detector delay function
0 = Disables the phase detector delay function
bit 2
PLLDD: PLL Dithering Disable bit
1 = Disables PLL dithering
0 = Enables PLL dithering
bit 1
Reserved: Write as ‘1’
bit 0
PLLBWB: PLL Bandwidth bit
Enabling the bit configures higher data rates, faster settling and reduced phase noise; thus, resulting
in a better RF performance.
1 = -102 dBc/Hz, > 90 kbps (max 256 kbps)
0 = -107 dBc/Hz, < 90 kbps (max 86.2 kbps)
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 41
Reg. Name
STSREG
CONTROL/COMMAND REGISTER MAP
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
TXOWRXOF WUTINT LCEXINT
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
AFCCT
OFFSV
Preliminary
TXRXFIFO
POR
LBTD
FIFOEM
ATRSSI
DQDO
CLKRL
GENCREG
1
0
0
0
0
0
0
0
TXDEN
FIFOEN
AFCCREG
1
1
0
0
0
1
0
0
TXCREG
1
0
0
1
1
0
0
MODPLY
TXBREG
1
0
1
1
1
0
0
0
CFSREG
1
0
1
0
RXCREG
1
0
0
1
0
FINTDIO
BBFCREG
1
1
0
0
0
0
1
0
RXFIFOREG
1
0
1
1
0
0
0
0
FIFORSTREG
1
1
0
0
1
0
1
0
SYNBREG
1
1
0
0
1
1
1
0
DRSREG
1
1
0
0
0
1
1
0
DRPE
PMCREG
1
0
0
0
0
0
1
0
RXCEN
WTSREG
1
1
1
DCSREG
1
1
0
0
1
0
0
0
BCSREG
1
1
0
0
0
0
0
0
PLLCREG
1
1
0
0
1
1
0
0
Bit 3
Bit 2
Bit 0
OFFSB<3:0>
FBS<1:0>
AUTOMS<1:0>
Bit 1
0x0000
LCS<3:0>
ARFO<1:0>
MFCS
MODBW<3:0>
HAM
—
0x8008
FOREN
FOFEN
OTXPWR<2:0>
TXDB<7:0>
RXBW<2:0>
ACRLC
0xB8AA
0xA680
RXLNA<1:0>
MCRLC
—
FTYPE
—
DRSSIT<2:0>
0x9080
DQTI<2:0>
0xC22C
RXDB<7:0>
FFBC<3:0>
0xB000
SYCHLEN
FFSC
FSCF
DRSTM
SYNCB<7:0>
TXCEN
SYNEN
WTEV<4:0>
OSCEN
0xC623
LBDEN
WUTEN
CLKOEN
WTMV<7:0>
—
CBTC<1:0>
—
1
DCMEN
LBDVB<3:0>
PDDS
0x8208
0xE196
DCMV<6:0>
COFSB<2:0>
0xCA80
0xCED4
DRPV<6:0>
BBCEN
0xC4F7
0x9800
FREQB<11:0>
DIORT<1:0>
Value
on POR
PLLDD
—
0xC80E
0xC000
PLLBWB
0xCC77
MRF49XA
DS70590C-page 42
TABLE 2-10:
© 2009-2011 Microchip Technology Inc.
MRF49XA
3.0
FUNCTIONAL DESCRIPTION
3.1
Reset
The MRF49XA is a low-power, Zero-IF, multi-channel
FSK transceiver which operates in the 433, 868
and 915 MHz frequency bands. All the RF and
baseband functions and processes are integrated in
the MRF49XA. The device for its operation requires
only a single, 10 MHz crystal as a reference source and
an external, low-cost host microcontroller. The
MRF49XA supports the following functions:
The MRF49XA supports four types of Reset:
•
•
•
•
•
•
•
•
•
The MRF49XA has a built-in Power-on Reset circuitry
which automatically resets all control registers when
power is applied. A delay of 100 ms is recommended
after a power-up sequence in order to allow the VDD to
reach the correct voltage level and to get stabilized to
recognize an active-low Reset. In Reset mode, the
device does not accept the control commands through
the SPI.
Reset
PA and LNA
Synthesizer (PLL, VCO and Oscillator)
I/Q Mixers and Demodulators
BBFs and Amplifiers
Received Signal Strength Indicator
Low Battery Detector
Wake-up Timer/Low Duty Cycle mode
DQI
The MRF49XA is the best option for FHSS applications
requiring frequency agility to meet Federal
Communications
Commission
(FCC),
Industry
Canada (IC)
or
European
Telecommunications
Standards Institute (ETSI) requirements. The
communication link can be created by just using the
MRF49XA along with a low-cost microcontroller. The
device uses the different power-saving modes to reduce
the overall current consumption, and thereby, extends
the battery life of the system or application.
FIGURE 3-1:
•
•
•
•
Power-on Reset
Power Glitch Reset
Software Reset
Reset Pin
3.1.1
POWER-ON RESET
After power-up, the supply voltage starts to rise
above 0V. The Reset block has an internal ramping
voltage reference level (Reset ramp signal) which rises
at a 100 mV/ms (typical) rate. The device remains in
the Reset state until the voltage difference between the
actual VDD and the internal Reset ramp signal is higher
than
the
Reset
threshold
voltage
level
(typically 600 mV). The device remains in Reset mode
as long as the VDD voltage level is less than 1.6V (typical), irrespective of the voltage difference between the
VDD and the internal ramp signal. Figure 3-1 graphically shows the POR example for VDD with respect to
time conditions.
POWER-ON RESET EXAMPLE
VDD
Reset Threshold
Voltage (600 mV)
1.6V
Reset Ramp
Line
(100 mV/ms)
Time
RESET
Output
(Pin 10)
H
L
© 2009-2011 Microchip Technology Inc.
The device stays in Reset when VDD < 1.6V
(even if the voltage difference is smaller
than the Reset threshold).
Preliminary
DS70590C-page 43
MRF49XA
3.1.2
POWER GLITCH RESET
Spikes or glitches are found on the VDD line if the power
supply filtering is not satisfactory, or the internal
resistance of the power supply is very high. So, in this
case, the Sensitive Reset mode needs to be enabled.
Here, the device Reset occurs due to the transients
present on the VDD line.
The internal Reset block has two basic modes of
operation:
The Sensitive Reset mode is the default mode which
can
be
changed
using
the
DRSTM
bit
(FIFORSTREG<0>). Figure 3-2 shows the Sensitive
Reset mode.
Normal Reset mode: The device enters this mode,
when the power glitch detection circuit is disabled.
Figure 3-3 shows the Normal Reset mode.
Note:
• Sensitive Reset mode
• Normal Reset mode
Sensitive Reset mode: Enabling the Sensitive Reset,
a Reset is generated if:
• the positive going edge of the VDD has a rising
rate greater than 100 mV/ms, and
• the voltage difference between the internal ramp
signal and the VDD reaches the Reset threshold
voltage (600 mV).
FIGURE 3-2:
Negative change in the supply voltage does
not cause a Reset event unless the VDD
level reaches the Reset threshold voltage
(i.e., 250 mV in Normal Reset mode, 1.6V in
Sensitive Reset mode).
If the Sensitive mode is disabled and the power supply
is turned off, the VDD requires 250 mV to trigger a
Power-on Reset when the supply voltage is reapplied.
If the decoupling capacitors retain their charges for a
longer duration, there might be no Reset after
power-up as the power glitch detector is disabled.
Note:
The Reset event reinitializes the internal
registers, and thus, the Sensitive mode is
enabled again.
SENSITIVE RESET ENABLED
V DD
Reset Threshold
Voltage (600 m V)
Reset Ram p Line
(100 m V/m s)
1.6V
Tim e
RESET
Output
(Pin 10)
H
L
DS70590C-page 44
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
FIGURE 3-3:
SENSITIVE RESET DISABLED
V DD
Reset Threshold
Voltage (600 mV)
Reset Ramp Line
(100 mV/ms)
250 mV
Time
RESET
Output
(Pin 10)
3.1.3
H
L
SOFTWARE RESET
The registers associated with Reset are:
The Software Reset is initiated using the host
microcontroller. The 0xFE00 command triggers this
Reset only if the Sensitive Reset mode is enabled. The
hardware automatically clears the bit(s) to their
power-on state. The Software Reset command is the
same as POR, but the duration of the Reset event is
much less than the actual POR (0.25 ms, typical).
3.1.4
• STSREG (see Register 2-1)
• FIFORSTREG (see Register 2-10)
• WTSREG (see Register 2-14)
RESET PIN
The MRF49XA has an open-drain Reset output with an
internal pull-up and input buffer (active-low). The host
microcontroller resets the MRF49XA by asserting the
RESET pin to low (see Figure 3-4). All control registers
are reset to their POR values. The RESET pin consists
of an internal weak pull-up resistor. In order to allow the
RF circuitry to start-up and get stabilized, a delay of
around 0.25 ms is recommended for accessing the
MRF49XA after a hardware Reset.
FIGURE 3-4:
RESET PIN INTERNAL
CONNECTION
V DD
To M CU Reset
(Input/Output*)
100k
To Internal
Reset Logic
RESET
Pin
N
10k
From POR
Circuit
V SS
* These pins can be left floating.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 45
MRF49XA
3.2
VDD Line Filtering
During the Reset event (caused by power-on, glitch on
the supply line or Software Reset), the VDD line should
be kept clean. Noise or a periodic disturbing signal
superimposed on the supply voltage may prevent the
device from getting out of the Reset state. To avoid this,
adequate filters should be made available on the power
supply lines to keep the distorting signal level
below 100 mVp-p, in the DC-50 kHz range for 200 ms,
from VDD ramp start. The usage of regulators or SMPS
may sometimes introduce switching noise on the VDD
line, so follow the power supply manufacturer’s
recommendations on how to decrease the ripple of
regulator IC and/or how to shift the switching frequency
while using SMPS.
The registers associated with power line filtering are:
• STSREG (see Register 2-1)
• FIFORSTREG (see Register 2-10)
• WTSREG (see Register 2-14)
DS70590C-page 46
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
3.3
Power and Low Noise Amplifiers
The PA is an open-collector, differential output with
programmable output power which can directly drive a
loop or dipole antenna, and with proper matching, can
also drive a monopole antenna. An automatic antenna
tuning circuit configured in the PA avoids the manual
tuning during production and this offsets “hand effects”.
TABLE 3-1:
PROGRAMMABLE LOAD
CAPACITANCE VALUE
CAP3
CAP2
CAP1
CAP0
Load
Capacitance
0
0
0
0
8.5
0
0
0
1
9
The registers associated with the PA are:
0
0
1
0
9.5
• TXCREG (see Register 2-4)
• PMCREG (see Register 2-13)
0
0
1
1
10
0
1
0
0
10.5
0
1
0
1
11
0
1
1
0
11.5
0
1
1
1
12
1
0
0
0
12.5
1
0
0
1
13
1
0
1
0
13.5
1
0
1
1
14
1
1
0
0
14.5
1
1
0
1
15
1
1
1
0
15.5
1
1
1
1
16
The input LNA has selectable gain (0 dB, -6 dB, -14 dB
and -20 dB) which is useful in environments with strong
interferers. The LNA has 250Ω of differential input
impedance, which requires a matching circuit when
connected to 50Ω devices.
The registers associated with the LNA are:
• RXCREG (see Register 2-7)
• PMCREG (see Register 2-13)
3.4
Crystal Oscillator and Clock
Output
The MRF49XA has a single pin crystal oscillator circuit,
which provides a 10 MHz reference signal for the
on-chip PLL. The clock frequency is programmable from
eight predefined frequencies, each being a prescaled
value of a 10 MHz crystal reference. A programmable
crystal load capacitor has been internally configured to
reduce the external component count and to have a
much simplified design. The internal load capacitor is
programmable from 8.5 pF – 16 pF in 0.5 pF steps as
defined GENCREG. This provides the advantage of
accepting a wide range of crystals from different
manufacturers with different load capacitance
requirements. For load capacitance values, see
Table 3-1. These values are programmable through the
BCSREG (see Register 2-16).
The crystal oscillator circuit is sensitive to parasitic
capacitance for start-up. A small amount of parasitic
capacitance is needed to facilitate oscillation. To achieve
this, create a ground plane around the crystal and widen
the connection to the MRF49XA. This is to adjust the
reference frequency and to compensate for stray
capacitance that might be introduced due to PCB layout.
If the layout is not possible, a 0.5 pF – 1 pF capacitor,
soldered across the crystal, will initiate the start-up. Also,
see Section 3.6, Crystal Selection Guidelines for
selecting the right crystal.
The crystal oscillator provides a reference signal to the
RF synthesizer, baseband circuits and digital signal
processing parts. If receiver or transmitter blocks are
used frequently, it is recommended to leave the
oscillator running because the crystal might need a few
milliseconds to start and stabilize. The stabilization
time mainly depends on the crystal parameters.
The CLKOEN bit (PMCREG<0>) is used to enable or
disable the clock output.
3.4.1
CLOCK TAIL FEATURE
The MRF49XA provides the clock signal for the
microcontroller for accurate timing, and thus, removes
the need for a second crystal for any board design.
When the microcontroller turns off the crystal oscillator
by clearing the OSCEN bit (PMCREG<3>), the
MRF49XA provides a fixed number (192) of further clock
pulses for the microcontroller to switch itself to Idle or
Sleep mode (Low-Power Consumption modes). To use
this feature, STSREG must be read before the OSCEN
bit is set to ‘0’. If STSREG is not read, then the clock
output will not shut down. If the CLKOUT pin is not used,
it is suggested to turn off the output buffer from
PMCREG.
Note:
Leaving blocks needlessly turned on
increases the current consumption, and
thus, reduces the battery life.
The microcontroller clock source (if the clock is not
supplied by the MRF49XA) should be stable enough
over temperature and voltage ranges to ensure a
minimum of 16 bits time delay under all operating
circumstances.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 47
MRF49XA
3.4.2
AUTO CRYSTAL OSCILLATOR
When an interrupt occurs, irrespective of the OSCEN bit
setting, the crystal oscillator automatically turns on to
supply a clock signal to the microcontroller. After clearing
all interrupts and reading the STSREG, the crystal
oscillator is automatically turned off. The clock tail feature
provides enough clock pulses for the microcontroller to
enter the Low-Power mode. Due to this automatic
feature, it is not possible to turn off the crystal by clearing
the OSCEN bit if any interrupt is active. For example,
after power-on, the POR interrupt must be cleared by
reading STSREG and then writing ‘0’ to the OSCEN bit
puts the part in Sleep mode. It is necessary to clear all
interrupts before turning the OSCEN bit off as the extra
current required for running the crystal oscillator can
shorten the battery life significantly.
On disabling the clock output (CLKOEN = 1), both the
clock tail and auto crystal oscillator usage features are
turned off. Only the OSCEN bit controls the crystal
oscillator (considering that both RXCEN and TXCEN
bits are cleared); the interrupts have no effect on it.
The registers associated with the crystal oscillator and
clock are:
•
•
•
•
•
STSREG (see Register 2-1)
AFCCREG (see Register 2-3)
PMCREG (see Register 2-13)
BCSREG (see Register 2-16)
PLLCREG (see Register 2-17)
3.5
Phase-Locked Loop
The synthesizer consists of a PLL, oscillator and VCO
for controlling the channel frequency. The synthesizer
must be enabled when either the transmitter or the
receiver is enabled. For faster RX/TX switching, the
synthesizer block must be kept on. Enabling the
transmitter using the TXCEN bit (PMCREG<5>) will
turn on the PA, and since the synthesizer is already up
and running, the PA immediately produces the TX
signal at the output. The oscillator must also be
enabled to provide the reference frequency for the PLL.
On power-up, the synthesizer performs the calibration
automatically. The synthesizer also has an internal
start-up calibration procedure. If there are significant
changes in voltage or temperature, recalibration should
be performed by simply disabling the synthesizer and
re-enabling it. When set, the SYNEN bit
(PMCREG<4>) enables the synthesizer.
DS70590C-page 48
The PLL circuit automatically performs the fine
adjustment of carrier frequency. This way, the receiver
can minimize the offset between a transmit and receive
frequency. The frequency control function can be
enabled or disabled through AFCCREG. The range of
offset can be programmed and the offset value is
calculated and added to the frequency control word
within the PLL to incrementally change the carrier
frequency. The MRF49XA can be programmed to
automatically change and control the carrier frequency.
The carrier frequency can also be manually activated
by a strobe signal.
The oscillator provides the reference signal to the RF
synthesizer to set up the transmit or receive frequency.
The crystal oscillator also provides a reference signal to
the RF, baseband circuits and microcontroller interface.
The PLL
following:
•
•
•
•
•
Configuration
register
configures
the
Output clock buffer slew rate
Crystal start-up time
Phase detector delay
PLL dithering
PLL bandwidth
The dithering reduces the noise error when calculating
the fractional-N synthesizer code. When the PLLDD bit
(PLLCREG<2>) is cleared, dithering is enabled and the
settling time is slightly increased. The PLL bandwidth
can accommodate higher data rates above 90 kbps.
The reduced PLL bandwidth allows faster settling time
and reduced phase noise, and thus, results in a better
RX performance. See Register 2-17 for details on PLL
setting and configuration.
The registers associated with the PLL are:
•
•
•
•
•
STSREG (see Register 2-1)
AFCCREG (see Register 2-3)
PMCREG (see Register 2-13)
BCSREG (see Register 2-16)
PLLCREG (see Register 2-17)
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
3.6
Crystal Selection Guidelines
The crystal oscillator of MRF49XA requires a 10 MHz
Parallel mode crystal. The circuit contains an
integrated load capacitor in order to minimize the
external component count. The internal load
capacitance value is programmable from 8.5 pF –
16 pF in 0.5 pF steps. With appropriate PCB layout, the
total load capacitance value can be 10 pF – 20 pF, so a
variety of crystal types can be used.
When the total load capacitance is not more than 20 pF,
and a worst case 7 pF Shunt Capacitance (CS) value is
expected for the crystal, the oscillator is able to start-up
with any crystal having less than 100Ω Equivalent
Series Loss Resistance (ESR). However, the low CS
and ESR values ensure the faster oscillator start-up.
FIGURE 3-5:
The Crystal Frequency (fref) is used as the reference of
the PLL, which generates the Local Oscillator
Frequency (fLO). Therefore, fLO is directly proportional to
fref. The accuracy requirements for production tolerance,
temperature drift and aging can thus be determined from
the maximum allowable local oscillator frequency error.
Whenever a low-frequency error is essential for the
application, it is possible to “pull” the crystal to the
accurate frequency by changing the load capacitor
value. The widest pulling range can be achieved if the
nominal required load capacitance of the crystal is in
the “midrange”; for example, 16 pF. The “pull-ability” of
the crystal is defined by its Motional Capacitance (Cm)
and shunt capacitance.
MAXIMUM CRYSTAL TOLERANCES INCLUDING TEMPERATURE AND AGING (ppm)
Bit Rate: 2.4 kbps
433 MHz
868 MHz
915 MHz
30
20
10
10
45
30
20
15
Deviation [± kHz]
60
75
50
70
25
30
25
30
90
90
40
40
105
100
50
50
120
100
60
50
45
30
15
15
Deviation [± kHz]
60
75
50
70
25
30
25
30
90
80
40
40
105
100
50
50
120
100
60
50
45
5
3
3
Deviation [± kHz]
60
75
20
30
10
20
10
15
90
50
25
25
105
75
30
30
120
75
40
40
Deviation [± kHz]
135
150
20
30
10
20
10
15
165
50
25
25
Bit Rate: 9.6 kbps
433 MHz
868 MHz
915 MHz
30
15
8
8
Bit Rate: 38.4 kbps
433 MHz
868 MHz
915 MHz
30
Do Not Use
Do Not Use
Do Not Use
Bit Rate: 115.2 kbps
433 MHz
868 MHz
915 MHz
105
Do Not Use
Do Not Use
Do Not Use
© 2009-2011 Microchip Technology Inc.
120
3
Do Not Use
Do Not Use
Preliminary
180
70
35
30
195
80
45
40
DS70590C-page 49
MRF49XA
3.7
Automatic Frequency Control
The AFC block operates in two modes and these
modes depend on the strobe signals which are
governed by the MFCS bit (AFCCREG<3>). The two
operating modes are as follows:
caused by the crystal tolerances. This method
allows the use of a low-cost quartz crystal in the
application and provides protection against
interference.
(AUTOMS1 = 1, AUTOMS0 = 0): The
frequency offset is automatically calculated
and the center frequency is corrected when
the DIO is high. When DIO goes low, the
calculated value is dropped.
3.
• Manual mode
• Automatic mode
Manual mode: In this mode, the microcontroller
provides the manual frequency control strobe signal.
See Register 2-3 (AFCCREG) for more details. One
measurement cycle can compensate for around 50% –
60% of the actual frequency offset. Two measurement
cycles can compensate for 80% and three measurement
cycles can compensate for 92% of the actual frequency
offset. The AFCCT bit (STSREG<5>) is used to
determine when the actual measurement cycle has
been completed.
Automatic mode: In this mode, the strobe signal from
the microcontroller is not required to update the
Frequency Offset register block, as shown in
Figure 3-6. The AFC circuit is automatically enabled
when the DIO indicates the potential incoming signal
during the entire measurement cycle and measures the
same result in two subsequent cycles. Without AFC,
the transmitter and the receiver need to be tuned
precisely to the same frequency. The RX/TX frequency
offset can lower the range. The units must be adjusted
carefully during the production. To avoid drift, a stable
and efficient crystal must be used or the output power
needs to be increased to compensate for yield loss.
The two methods recommended for improving the
accuracy of the AFC calculation are as follows:
• The transmit package should start with a low
effective baud rate pattern (i.e., 00110011b) as it
is easier to receive. The circuit automatically
measures the frequency offset during this initial
pattern and changes the receiving frequency
accordingly. The remaining part of the package
will be received by the corrected frequency
settings.
• The transmitter sends the first part of the packet
with a higher deviation step than required during
normal operation to help reception. After the
frequency shift correction, the deviation can be
reduced.
In both methods, when the DIO indicates poor receiving
conditions (i.e., when DIO goes low), the output register
is automatically cleared. This mode (Drop Offset mode)
is used when the receiver communicates with more than
one transmitter.
4.
(AUTOMS1 = 1, AUTOMS0 = 1): This mode
(Keep Offset mode) is similar to Drop Offset
mode, but is recommended for use when the
receiver communicates with only one
transmitter. After a complete measuring cycle,
the measured value is kept independent of the
state of the DIO signal. In this mode, the DRSSI
limit should be carefully selected to minimize the
range hysteresis.
The AFC block calculates the TX/RX offset using the
OFFSB bits (STSREG<3:0>). This value is used to pull
the RX synthesizer close to the transmitter frequency.
The benefits of the AFC feature are:
• Low-cost crystal can be used
• Temperature or aging drift will not cause range
loss
• Production alignment is not needed
Figure 3-6 depicts the AFC circuit for frequency offset
correction.
The Automatic mode Selection bits, AUTOMS<1:0>
(AFCCREG<7:6>), select the type of operation
(automatic or manual) for performing the AFC based on
the status of the MFCS bit (AFCCREG<3>). There are
four types of operation modes for controlling the
frequency:
1.
2.
(AUTOMS1 = 0, AUTOMS0 = 0): Automatic
operation of AFC is off. The MFCS bit is
controlled by the microcontroller.
(AUTOMS1 = 0, AUTOMS0 = 1): The circuit
measures the frequency offset only once after
power-up. Hence, extended TX to RX distance
can be achieved. In the actual application, when
the user applies a battery, the circuit measures
and compensates for the frequency offset
DS70590C-page 50
The AFC Offset Value (OFFSB<3:0> bits in the status
word) is represented as a two’s complement number.
The actual frequency offset is calculated as the AFC
offset value multiplied by the current PLL frequency
step (see Register 2-6 for more details).
The actual RX/TX offset can be monitored by using the
AFC status report (i.e., AFCCT bit) included in the status
word of the receiver. By reading out the status word, the
actual measured offset frequency can be derived. To get
accurate values, the AFC has to be disabled during read
by clearing the FOFEN bit (AFCCREG<0>).
The registers associated with AFC are:
•
•
•
•
•
STSREG (see Register 2-1)
AFCCREG (see Register 2-3)
CFSREG (see Register 2-6)
RXCREG (see Register 2-7)
PLLCREG (see Register 2-17)
Preliminary
© 2009-2011 Microchip Technology Inc.
© 2009-2011 Microchip Technology Inc.
FIGURE 3-6:
AFC CIRCUIT FOR FREQUENCY OFFSET CORRECTION
Baseband Signal IN
AFCCT
STSIG
HAM
FINE
SEL
10 Y
10 MHz CLK
/4
11
MUX
FIFOEN
Enable Calculation
CLK
Digital AFC
Core Logic
OFFSB
<6:0>
7-Bit
Digital Limiter
If IN > MaxDEV then,
OUT = MaxDEV
7
7
If IN < MinDEV then,
OUT = MinDEV
Frequency
Offset
Register
DIO
AUTOMS<1:0>
Auto Operation
Signals for Auto
Operation modes
ADDER
FCOR<11:0>
Corrected Frequency
Parameter to
Synthesizer
ELSE,
OUT = IN
Preliminary
CLK
POR
ARFO<1:0>
12-Bit
CLR
Range Limit
Strobe
MFCS
Strobe
Output Enable
FOREN
Output Enable
FREQB<11:0>
DS70590C-page 51
MRF49XA
Parameter from Frequency
Control Word
MRF49XA
3.8
Initialization
3.9
Certain control register values must be initialized for
the basic operations of MRF49XA. These values differ
from the Power-on Reset values and provide improved
operational parameters. These settings are normally
made once after a Reset. After initialization, the
MRF49XA device features can be configured for the
application. Here, accessing a register is implied as a
command to the MRF49XA device through the SPI
port. The steps to be followed for the initialization of
MRF49XA using the control registers are as follows:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Set FIFORSTREG.
Enable synchronous latch from FIFORSTREG.
Program frequency band and crystal load
capacitance from GENCREG.
Enable AFC function from AFCCREG.
Set center frequency through CFSREG for
transmit or receive frequency.
Set data rate through DRSREG.
Enable required functions (transmit, receive,
etc.) from PMCREG.
Configure RXCREG.
Configure TXCREG.
Tune in the antenna.
Turn off the transmitter and turn on the receiver.
Enable FIFO for data reception.
Set FIFORSTREG.
Enable synchronous latch from FIFORSTREG.
Read STSREG.
Interrupts
The advanced interrupt handler circuit is implemented
in the MRF49XA to reduce the power consumption. As
mentioned, the Sleep mode is the lowest power
consumption mode in which the mode clock and all
functional blocks of the chip are disabled. However, the
WUT and LBD circuits can be active if enabled. In case
of any interrupt, the device wakes up, switches to the
Active mode and an interrupt signal generated on the
IRO pin of the device indicates the change in state or
occurrence of an interrupt to the host microcontroller.
The source of the interrupt is determined by reading the
status word of the device (see Register 2-1).
The receiver generates an active-low interrupt request
for the microcontroller at the following events:
• TXBREG is ready to receive the next byte
• RXFIFOREG has received the preprogrammed
amount of bits
• RXFIFOREG overflow/TXBREG underrun
• Negative pulse on Interrupt Input pin (INT)
• Wake-up Timer Time-out (WUTINT)
• Supply voltage below the preprogrammed value is
detected
• Power-on Reset
The following steps should be followed to tune in the
antenna section:
1.
2.
Turn on the transmitter section from PMCREG.
Wait for 5 ms for the oscillator to get stabilized.
The registers associated with initialization are:
•
•
•
•
•
•
•
•
•
STSREG (see Register 2-1)
GENCREG (see Register 2-2)
AFCCREG (see Register 2-3)
TXCREG (see Register 2-4)
CFSREG (see Register 2-6)
RXCREG (see Register 2-7)
FIFORSTREG (see Register 2-10)
DRSREG (see Register 2-12)
PMCREG (see Register 2-13)
DS70590C-page 52
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
3.9.1
SETTING INTERRUPTS
3.9.1.4
The device’s interrupt pin (IRO) signals one of eight
interrupt events to the host microcontroller. The
interrupt source in the microcontroller is read out from
the transceiver through the SDO pin. The interrupt
sources that are available are briefly described in the
following subsections.
3.9.1.1
1.
TXRXFIFO: Transmit Register or
Receive FIFO bit
Transmit mode: Transmit Register Ready bit
This interrupt is generated when the Transmit
register is empty. It is valid only when the
TXDEN bit (GENCREG<7>) is set and the
TXCEN bit (PMCREG<5>) is enabled.
2.
Receive mode: Receive FIFO Empty bit
This interrupt is generated when the bit level in
the
RXFIFOREG
has
reached
the
preprogrammed level. An interrupt is triggered
when the number of received data bits in the
receiver FIFO reaches the threshold set by the
FFBC bits (FIFORSTREG<7:4>). This is valid
only when the FIFOEN bit (GENCREG<6>) is set
and the RXCEN bit (PMCREG<7>) is enabled.
3.9.1.2
POR: Power-on Reset Interrupt
The POR interrupt is generated when a change on the
VDD line triggers an internal Reset circuit or a Software
Reset was issued. For details, see Section 3.1, Reset.
3.9.1.3
1.
2.
TXOWRXOF: Transmit Overwrite
Receive Overflow bit
WUTINT: Wake-up Timer Interrupt
This interrupt occurs when the time specified by the
wake-up timer has elapsed. It is valid only when the
WUTEN bit (PMCREG<1>) is set. The device
periodically wakes up and switches to Receive mode. If
valid FSK data is received, the device sends an
interrupt to the microcontroller and continues filling the
RXFIFO. After the completion of transmission, the
FIFO is read out completely and all other interrupts are
cleared. The device returns to the Low-Power
Consumption mode.
3.9.1.5
LCEXINT: Logic Low-Level Change
on External Interrupt
Follows the level of the INT pin if configured as an
external interrupt by clearing the FINTDIO bit
(RXCREG<10>).
3.9.1.6
LBTD: Low Battery Threshold Detect
This interrupt occurs when VDD goes below the
programmable low battery detector threshold level
configured by the LBDVB bits (BCSREG<3:0>). It is
valid only when the LBDEN bit (PMCREG<2>) is set.
3.9.2
CLEARING INTERRUPTS
If any of the interrupt sources gets active, the IRO
changes to logic low level and the corresponding
interrupt bit in the status byte goes high. Clearing an
interrupt implies:
• releasing the IRO pin to return to logic high, and
• clearing the corresponding interrupt bit in the
STSREG
Transmit mode: Transmit Register Underrun or
Overwrite bit
The clearing of each of the interrupts is briefly
described in the following subsections.
This interrupt is generated when the automatic
Baud Rate Generator (BRG) has completed the
transmission of a byte in TXBREG before the
register write. It is valid only when the TXDEN bit
(GENCREG<7>) is set and the TXCEN bit
(PMCREG<5>) is enabled.
3.9.2.1
1.
Transmit mode
The IRO pin and its status bit remain active until
the register is written (if underrun does not occur
until the register write) or the transmitter and the
TX latch are switched off.
Receive mode: Receive FIFO Overflow bit
This interrupt is generated when the bits
received are more than the FIFO capacity
(16 bits). This is valid only when the FIFOEN bit
(GENCREG<6>) is set and the RXCEN bit
(PMCREG<7>) is enabled.
TXRXFIFO
2.
Receive mode
The IRO pin and its status bit remain active until
the FIFO is read (receive FIFO interrupt
threshold number of bits have been read). The
receiver is switched off or the RXFIFO is
switched off.
3.9.2.2
POR
The IRO pin and its status bit are cleared by reading the
Status Read register.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 53
MRF49XA
3.9.2.3
1.
TXOWRXOF
Transmit mode
In this mode, the TXOWRXOF and TXRXFIFO
bits are always set together. The IRO pin and its
status bit remain active until the transmitter and
the TX latch are switched off.
2.
Receive mode
In this mode, the TXOWRXOF and TXRXFIFO
bits are always set together and can be cleared
by reading the STSREG. The IRO pin and its
status bit remain active until the FIFO is read (a
FIFO interrupt threshold number of bits have
been read), the receiver is switched off or the
RX FIFO is switched off.
3.9.2.4
WUTINT
The IRO pin and its status bit are cleared by reading
the STSREG.
3.9.2.5
LCEXINT
feature provides sufficient clock pulses for the
microcontroller to enter the Low-Power Consumption
mode. Due to this automatic feature, it is not possible to
turn off the crystal by clearing the OSCEN bit if any
interrupt is active.
For example, after power-on, the POR interrupt must
be cleared by a status read, and then by writing ‘0’ in
the OSCEN bit, puts the device into Sleep mode.
Note:
Before turning the OSCEN bit off, clear all
the interrupts, because the additional
current required for running the crystal
oscillator can shorten the battery life
significantly.
The registers associated with interrupts are:
•
•
•
•
•
STSREG (see Register 2-1)
GENCREG (see Register 2-2)
RXCREG (see Register 2-7)
PMCREG (see Register 2-13)
BCSREG (see Register 2-16)
The IRO pin and its status bit follow the level of the INT pin.
3.9.2.6
LBTD
The IRO pin is released by reading the status bit of
STSREG, but the status bit remains active until the VDD
is below the threshold value.
The MRF49XA interrupt generation logic is shown in
Figure 3-7. A better way of interrupt handling is to first
read the STSREG on an interrupt and then decide the
action based on the status byte/word. It is important to
note that any of the interrupt sources can wake-up the
MRF49XA from Sleep mode. This means that the
crystal oscillator starts to supply a clock signal to the
microcontroller even if the microcontroller has its own
clock source. The MRF49XA will not enter Sleep mode
if any of the interrupt remains active, irrespective of the
state of the OSCEN bit in PMCREG. This way, the
microcontroller can always have a clock signal to
process the interrupt.
To prevent high-current consumption, which results in
short battery life, it is highly recommended to process
and clear interrupts before entering Sleep mode. The
functions which are not necessary should be turned off
to avoid unwanted interrupts. Before finalizing the
microcontroller (application) code, a thorough testing
must be conducted to make sure that all interrupt
sources are handled before putting the transceiver in
Sleep mode.
The OSCEN bit controls the crystal oscillator
(considering that the RXCEN and TXCEN bits are
cleared) if the CLKOEN bit (PMCREG<0>) is set. The
interrupts have no effect on it.
On interrupt, the crystal oscillator turns on automatically
to supply a clock signal to the microcontroller,
irrespective of the OSCEN bit setting. The clock tail
DS70590C-page 54
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
FIGURE 3-7:
MRF49XA INTERRUPT GENERATION LOGIC
TXRXFIFO
TXCEN
TXRXFIFO
RXCEN
RESET
(Ext./Int.)
TXOWRXOF
TXCEN
IRO
TXOWRXOF
RXCEN
WUTINT
WUTEN
LCEXINT (INT)
FINTDIO
LBTD
LBDEN
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 55
MRF49XA
3.10
Baseband/Data Filtering
A suitable bandwidth should be used to achieve various
FSK deviation, data rate and crystal tolerance requirements. The filter structure is a 7th order, Butterworth
low-pass with 40 dB suppression at twice the bandwidth
frequency. Offset cancellation is done by using a
high-pass filter, with a cutoff frequency below 7 kHz, in
order to achieve the best possible frequency response in
baseband and a good flat response in the pass band.
Figure 3-8 shows the full baseband amplifier transfer
function. This optimizes the chip area, cost and channel
separation.
The baseband receiver has several programming
options to optimize the communication for a wide range
of applications. The programmable functions are as
follows:
•
•
•
•
•
Baseband Analog Filter
Baseband Digital Filter
Receive Bandwidth
Receive Data Rate
Clock Recovery
FIGURE 3-8:
FULL BASEBAND AMPLIFIER TRANSFER FUNCTION (BW = 67 kHz)
40
Output Power Level (dB)
20
0
-20
-40
-60
-80
-100
-120
-140
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E+06
Frequency (Hz)
The receive bandwidth is programmable from 67 kHz to
400 kHz to accommodate various FSK modulation
deviations. If the deviation is known for a given
transmitter, good results are obtained with a bandwidth
of at least twice the transmitter FSK deviation.
EXAMPLE 3-1:
•
•
•
•
Example 3-1 shows the method to calculate the
recommended frequency deviation and BBBW for the
given specifications.
FREQUENCY DEVIATION AND BBBW CALCULATION
Data Rate – 9.6 kbps
Crystal Accuracy – 40 ppm
Frequency Band – 915 MHz
fxerror by the Crystal: 40 x (915000/1000000) = 36.6 kHz
Deviation = Data Rate + 2 x fxerror + 10 = 9.6 + 2 x 36.6 + 10 = 92.8 kHz
The closest possible deviation is 90 kHz.
BBBW = Deviation x 2 – 10 kHz = 90 x 2 – 10 = 170 kHz
The closest possible BBBW is 200 kHz.
The FSK modulated deviation for this example is shown in Figure 3-9.
DS70590C-page 56
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
FIGURE 3-9:
FSK MODULATED DEVIATION – MAXIMUM TX TO RX OFFSET
2 x deviation
Amplitude
10 kHz + Data Rate
Baseband Filter Characteristic
Data Rate
TX-RX Offset
Frequency
BBBW
Programmable
The baseband filtering type can also be selected
between an analog filter and a digital filter.
3.10.1
ANALOG FILTERING MODE
For analog filtering, a simple RC low-pass filter is used,
along with a Schmitt Trigger circuit. The demodulator
output is fed to the RCLKOUT/FCAP/FINT pin over a
10 kΩ resistor. The filter cut-off frequency is set by the
external capacitor connected to this pin and VSS. A
10 kΩ resistor and the Schmitt Trigger are integrated
on the chip. An external capacitor for the RC filter has
to be chosen in accordance with the required bit rate.
The receiver can handle up to 256 kbps of data rate in
analog operation. The receive data rate is
programmable from 337 bps to 256 kbps. An internal
prescaler can be used to give better resolution when
setting up the receive data rate. The prescaler is
optional and can be disabled through DRSREG. The
analog filtering does not use the FIFO and the clock.
The clock is not provided for the demodulated data,
and hence, there is no need for setting the correct bit
rate.
© 2009-2011 Microchip Technology Inc.
RX Center
Freq.
10 kHz
3.10.2
TX Center
Freq.
DIGITAL FILTERING MODE
A digital filter is used with a clock frequency at 29 times
the data rate. For digital filtering, the synchronized
clock to the data is provided by the CLKRC. By using
this clock, the received data can fill the FIFO. If the
FIFO is not used, the recovered clock can be accessed
through RCLKOUT/FCAP/ FINT pin.
The CLKRC operates in three modes: Automatic mode,
Slow mode and Fast mode. All three modes are
configurable through BBFCREG. Each mode is
dependent on the type of signals it uses to determine
the valid data and also the number of incoming
preamble bits present at the beginning of the packet. In
Automatic mode, the CR CLKRC automatically
switches between the Fast and Slow mode. The noise
immunity of the CLKRC is very high in Slow mode;
however, it has slower settling time and requires more
accurate data timing than in Fast mode.
The registers associated with baseband filtering are:
•
•
•
•
STSREG (see Register 2-1)
RXCREG (see Register 2-7)
BBFCREG (see Register 2-8)
PMCREG (see Register 2-13)
Preliminary
DS70590C-page 57
MRF49XA
3.11
Data Quality Indicator
can prevent the crystal oscillator from starting, or the
DQI signal will not go high, even when the quality of the
received signal is good.
The DQI is the digital processing part of the radio
connected to the demodulator and functions when the
receiver is on. This reports the reception of an FSK
modulated RF signal. The DQI parameter setting
defines how clean the incoming data stream would be
stated as good data (valid FSK signal). The DIO signal
goes high if the internally calculated data quality value
exceeds the DIO threshold parameter, for five
consecutive data bits, for both high and low periods.
The DIO is an extension of the DQI. When incoming
data is detected, it uses the DQI signal, the clock
recovery lock signal and the digital RSSI signal to
determine if the incoming data is valid. The desired
data rate and the acceptance criteria for valid data are
user-programmable through the SPI port.
The DIO has three modes of operation: Slow, Medium
and Fast. Each mode is dependent on the signals it
uses to determine the valid data and also on the
number of incoming preamble bits present at the
beginning of the packet.
The DQI parameter (i.e., Data Quality Threshold
Indicator (DQTI) bit) value is calculated using the
formula given in Equation 3-1.
EQUATION 3-1:
The DIO can be disabled by the user so that only raw
data from the comparator comes out, or it can be set to
accept only a preset range of data rates and data
quality. The DIO saves the battery power and the time
for a host microcontroller because it will not wake-up
the microcontroller unless there is valid data present.
See Register 2-7 (RXCREG) for setup details.
DQIpar = 4 x (Deviation – TX/RXoffset)/Bit Rate
The DQI parameter in BBFCREG should be chosen
according to the following rules:
• The parameter should be > 4; otherwise, noise
might be treated as a valid FSK signal
• The maximum value is 7
The DIO signal is valid when using the internal receive
FIFO or an external pin to capture baseband data. DIO
can be multiplexed to pin 16 for external usage.
Figure 3-10 depicts the DIO logic block diagram.
Even during the on-time calculation in the Low Duty
Cycle mode, depending on the data quality threshold
indicator, the device needs to receive a few valid data
bits before the DQI signal indicates good signal
condition (see Register 2-8). Selecting a short on-time
FIGURE 3-10:
DIO LOGIC BLOCK DIAGRAM
MUX
DQI
DIORT0
SEL0
DIORT1
CR_LOCK
SEL1
FAST
IN0
MEDIUM
DRSSI
IN1
SLOW
DQI
IN2
LOGIC HIGH
DRSSI
DQI
CR_LOCK
SET
Y
DIO
IN3
CLR
Q
RXCEN
R/S
FLIP/FLOP
CLR
DS70590C-page 58
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
The DIO signal response time setting is configured
through RXCREG and has the following modes of
operation:
• Default mode: The DIO is permanently
connected to logic high. It always stays high
independent of the receiving parameters.
• Slow mode: The DIO signal goes high if the
digital RSSI, DQI and Clock Recovery Lock
(CR_LOCK) signals are present. It stays high
until any of these signals are present and goes
low when all three input signals are low.
• Medium mode: The DIO signal is active when
the CR_LOCK and the DRSSI or the DQI signals
are high. It goes low when either the CR_LOCK
becomes inactive or the DRSSI or DQI signals
goes low.
• Fast mode: The DIO signal follows the level of
the DQI signal.
The registers associated with DQI are:
• STSREG (see Register 2-1)
• RXCREG (see Register 2-7)
• BBFCREG (see Register 2-8)
3.12
Programmable Synchronous Byte
The internal synchronous pattern and the pattern
length are user-programmable. The MRF49XA is
configured to use a synchronous character to indicate
the valid incoming data. The synchronous character
selection is done through the FIFORSTREG. The
character is divided into two bytes: SCL1 and SCL0.
The SCL0 byte is user-configurable, whereas SCL1 is
fixed to 2Dh and is non-programmable. The
synchronous character can also be configured as a
byte character or a word character. A byte character
uses only SCL0, whereas the word character uses
both
SCL1
and
SCL0.
Since
SCL0
is
user-configurable, it is advantageous while operating
under interferences and also while identifying the
related transmitters.
The registers associated with the programmable
synchronous byte are:
• FIFORSTREG (see Register 2-10)
• PMCREG (see Register 2-13)
© 2009-2011 Microchip Technology Inc.
3.13
Received Signal Strength
Indicator
The Received Signal Strength Indicator (RSSI)
estimates the received signal power within the
bandwidth of ISM channels. The MRF49XA provides
both analog RSSI and digital RSSI. A digital RSSI output
is provided to monitor the input signal level. The signal
goes high if the received signal strength exceeds a given
preprogrammed level. The digital RSSI threshold is
programmable through RXCREG, and is read and
monitored only through STSREG. When an incoming
signal is stronger than the preprogrammed threshold, the
digital RSSI bit in the STSREG is set. The settling time of
digital RSSI depends on the external filter capacitor.
The DRSSIT value is a 3-bit binary value ranging from
0 to 8. Table 3-2 shows the mapping between the
DRSSIT value versus the received power level. The
number of symbols to average can be changed by
programming the DRSSIT bits (RXCREG<2:0>).
The digital RSSI is basically a sensitive comparator
behind an analog RSSI block. The comparator
threshold can be set using the three bits and the
comparator output can be read out through the Status
Read register. The curve in Figure 3-11 shows the
analog RSSI output voltage versus signal strength.
The analog RSSI level is linear with input signal levels
between -103 dBm and -73 dBm. The RSSIO pin in
MRF49XA is used as an analog RSSI output and better
results can be achieved by using this pin with a
sensitive comparator.
These bits can be set to indicate the incoming signal
strength above a preset limit. The result enables or
disables the DQDO bit (STSREG<7>). The RSSI
threshold depends on the LNA gain and the real RSSI
threshold can be calculated by using the formula as
given in Equation 3-2.
EQUATION 3-2:
RSSIth = RSSIsetth + GLNA
In Transmit mode, the ATRSSI bit (STSREG<8>)
indicates that the antenna tuning circuit has detected a
relatively strong RF signal.
In Receive mode, the ATRSSI bit indicates that the
incoming RF signal is above the preprogrammed
digital RSSI threshold.
Preliminary
DS70590C-page 59
MRF49XA
TABLE 3-2:
DIGITAL RSSI THRESHOLD LEVELS
RSSI Threshold
DRSSIT2
DRSSIT1
DRSSIT0
Reserved
1
1
1
Reserved
1
1
0
-73
1
0
1
-79
1
0
0
-85
0
1
1
-91
0
1
0
-97
0
0
1
-103
0
0
0
FIGURE 3-11:
INPUT POWER VS. ANALOG RSSI VOLTAGE
1.2
1
0.6
RSSI (V)
0.8
0.4
0.2
0
-112
-102
-92
-82
-72
-62
-52
-42
Input Power (dBm)
3.13.1
RELATIONSHIP BETWEEN RSSI
AND CLOCK RECOVERY
3.13.2
The DIO signal response time setting is configured
through RXCREG and has the following modes of
operation:
•
•
•
•
Normal mode
Slow mode
Medium mode
Fast mode
These operation modes are configurable through
BBFCREG.
In Medium mode, the DIO signal is active when the
CR_LOCK and the DRSSI or the DQI signals are high.
The DIO goes low when either the CR_LOCK turns
inactive, or the DRSSI or DQI signals go low. For more
details on DQI, see Section 3.11, Data Quality
Indicator.
DS70590C-page 60
RELATIONSHIP BETWEEN RSSI
AND AFC
The Keep Offset mode of automatic configuration of
AFC (i.e., AUTOMS1 = 1, AUTOMS0 =
1) is
recommended to be used when a receiver operates
with only one transmitter. After a complete measuring
cycle, the measured value is kept independent from
the state of the DIO signal. In this mode, the DRSSI
limit should be carefully selected to minimize the range
hysteresis.
The registers associated with RSSI are:
•
•
•
•
STSREG (see Register 2-1)
GENCREG (see Register 2-2)
RXCREG (see Register 2-7)
PMCREG (see Register 2-13)
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
3.14
Power Management
The Power Management Configuration
enables/disables the following functions:
•
•
•
•
•
•
•
•
register
Receiver
Transmitter
Baseband Circuit
Synthesizer
Crystal Oscillator
Low Battery Detect Circuit
Wake-up Timer
Clock Output
Clock Output: The CLKOEN bit, when set, disables
the oscillator clock output. On device Reset or
power-up, the clock output is enabled so that a
processor can begin execution of any special setup
sequences as required by the designer. See
Register 2-16 (BCSREG) for programming details.
Note:
Figure 3-12 shows the functions that are enabled using
PMCREG.
Receiver: The RXCEN bit, when set, enables the
entire receiver chain. The receiver chain consists of a
baseband circuit, synthesizer and crystal oscillator.
Transmitter: The TXCEN bit, when set, enables the
entire transmit chain. The transmit chain consists of a
power amplifier, synthesizer, oscillator and transmit
register. When the transmit chain and Transmit register
are enabled, any data in the Transmit register is shifted
out and a transmission is started.
Baseband Circuit: The BBCEN bit, when set, enables
the baseband circuit. The baseband circuit, synthesizer
and oscillator work together to demodulate and recover
the data transmitted to the synthesizer (SYNEN bit). If
baseband circuits are enabled, then the oscillator
(OSCEN bit) must be enabled in order to receive data.
The BBCEN bit can be disabled to reduce current
consumption.
Synthesizer: The SYNEN bit, when set, enables the
synthesizer. The synthesizer is comprised of a PLL,
oscillator and VCO for controlling the channel frequency.
This bit must be enabled when either the transmitter or
the receiver is enabled. The oscillator must also be
enabled to provide the reference frequency for the PLL.
On power-up, the synthesizer automatically performs
the calibration. If there are significant changes in voltage
or temperature, recalibration can be performed by
disabling and re-enabling the synthesizer.
If bit 0 is cleared, and with the clock
output enabled, the oscillator continues to
run even if the OSCEN bit is cleared. The
device will not fully enter Sleep mode.
The RF front end is comprised of the LNA and the
mixer. The synthesizer block has two main
components: the VCO and the PLL. The baseband
section consists of a baseband amplifier, low-pass
filter, limiter and I/Q demodulator.
The synthesizer also has an internal start-up calibration
procedure. If quick RX/TX switching is needed, leave
this block on. Enabling the transmitter using the
TXCEN bit (PMCREG<5>) will turn on the PA, and
since the synthesizer is already up and running, the PA
immediately produces the TX signal at the output.
To decrease the TX/RX turnaround time, keep the
baseband section on. Switching to Receive mode
means disabling the PA and enabling the RF front end.
Since the baseband block is already on, the internal
start-up calibration is skipped, and thus, the turnaround
time is shorter. The BBCEN, SYNEN and OSCEN bits
are provided to optimize the TX to RX or RX to TX
turnaround time.
The crystal oscillator provides a reference signal to the
RF synthesizer, baseband circuit and digital signal
processor. If the receiver or the transmitter is frequently
used, it is recommended to leave the oscillator running
as the crystal might need a few milliseconds to start. The
start timing mainly depends on the crystal parameters.
Note:
Leaving blocks unnecessarily turned on
increases the current consumption, and
thus, decreases the battery life.
Crystal Oscillator: The OSCEN bit, when set, enables
the oscillator circuit. The oscillator provides the
reference signal to the synthesizer when setting the
transmit or receive frequency of use.
Low Battery Detect Circuit: The LBDEN bit, when
set, enables the battery voltage detect circuit. The
battery detector can be programmed to 32 different
threshold levels. See Register 2-16 (BCSREG) for
programming details.
Wake-up Timer: The WUTEN bit, when set, enables
the wake-up timer. See Register 2-14 (WTSREG) for
details on programming the wake-up timer interval.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 61
MRF49XA
From PMCREG, the following points are applicable
when using the bit functionalities:
• The chip enters Receive mode if both the TXCEN
and RXCEN bits are set.
• FSK/DATA/FSEL input is equipped with an internal
pull-up resistor. To achieve minimum current
consumption, do not pull this input to logic low in
Sleep mode.
• To enable the RF synthesizer, the crystal oscillator
must be turned on.
• To turn on the baseband circuits, the RF
synthesizer and the crystal oscillator must be
enabled.
• Setting the RXCEN bit automatically turns on the
crystal oscillator, synthesizer, baseband circuits
and RF front end.
• Setting the TXCEN bit automatically turns on the
crystal oscillator, synthesizer and RF power
amplifier.
DS70590C-page 62
The clock tail and automatic crystal enable/disable
features help in reducing the power consumption and
are discussed in detail in Section 3.4, Crystal
Oscillator and Clock Output.
The registers associated with power management are:
•
•
•
•
STSREG (see Register 2-1)
GENCREG (see Register 2-2)
RXCREG (see Register 2-7)
PMCREG (see Register 2-13)
Preliminary
© 2009-2011 Microchip Technology Inc.
© 2009-2011 Microchip Technology Inc.
FIGURE 3-12:
LOGIC CONNECTIONS BETWEEN POWER CONTROL BITS
Enable Power
Amplifier
TXCEN
Start TX
Enable Power
Amplifier
Edge
Detector
LNA
PA
Enable RF Front End
Clear TX Latch
(If TX latch is used)
Enable RF
Synthesizer
VCO and PLL
Preliminary
SYNEN
Enable RF
Synthesizer
(Crystal Synthesizer
must be ON)
Start TX
Clear TX Latch
RXCEN
TX Latch
Enable RF Front
End
Enable Baseband
Circuits
Enable Crystal
Oscillator
Crystal Oscillator
I/Q
Demod.
Enable Baseband
Circuits
BBCEN
Digital Signal
Processing
DS70590C-page 63
Enable Crystal
Oscillator
OSCEN
MRF49XA
(RF Synthesizer
must be ON)
MRF49XA
3.15
Low Duty Cycle Mode
In Low Duty Cycle mode, the receiver periodically
wakes up for a short period and checks for the valid
FSK transmission in progress. The FSK transmission is
detected in the frequency range determined by
CFSREG and the baseband filter bandwidth is
determined by the RXCREG. The on time is
automatically extended until the DQI indicates a good
received signal condition.
completely and all other interrupts are cleared. The
device then returns to the Low-Power Consumption
mode. Figure 3-13 depicts the Low-Power Duty Cycle
mode sequence.
The low duty cycle is calculated by using the DCMV
(DCSREG<7:1>) and WTMV (WTSREG<7:0>) bits, as
shown in Equation 3-3. The time cycle is determined by
the WTSREG.
EQUATION 3-3:
The following facts need to be considered while
calculating the duty cycle on-time:
• The crystal oscillator, the synthesizer and the PLL
need time to start (see Table 5-7).
• Depending on the DQTI, the device needs to
receive few valid data bits before the DQI signal
indicates a good signal condition (see
Register 2-8).
Selecting a short on-time can prevent the crystal
oscillator from starting, or the DQI signal will not go high
even when the received signal has a good quality. The
MRF49XA is normally configured to work in FIFO mode.
However, when the device periodically wakes up from
Sleep mode, it switches to the Receive mode. If valid
FSK data is received, the device sends an interrupt to
the microcontroller and continues filling the RXFIFO. On
completion of transmission, the FIFO is read out
FIGURE 3-13:
DC = (DCMV<7:1> x 2 + 1)/WTMV<7:0> x 100%
Note:
The registers associated with Low Duty Cycle mode
are:
•
•
•
•
•
•
STSREG (see Register 2-1)
GENCREG (see Register 2-2)
RCXREG (see Register 2-7)
BBFCREG (see Register 2-8)
PMCREG (see Register 2-13)
WTSREG (see Register 2-14)
LOW-POWER DUTY CYCLE MODE SEQUENCE
Start/Send
Start/Send
Packet A
Transmitter
In Duty Cycle mode, the RXCEN bit must
be cleared and the WUTEN bit must be
set in PMCREG.
Packet A
Packet A
Packet
B. B. B. B.
Receiver
TWAKE-up
Receiving
Packet A
Packet A
Packet
B.
DQI
IRO
Microcontroller
Operation
DS70590C-page 64
FIFO Read
FIFO Read
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
3.16
Sleep, Wake-up and Battery
Operations
The advanced interrupt handler circuit is configured in
the transmitter to reduce the power consumption. As
mentioned, the Sleep mode is the lowest power
consumption mode in which the clock and all functional
blocks of the device are disabled. In case of any
interrupt, the device wakes up, switches to Active mode
and an interrupt signal generated on the IRO pin
indicates the change in state to the host
microcontroller. The source of the interrupt can be
determined by reading the status word of the device
(see Register 2-1).
To reduce current consumption, the MRF49XA should
be placed in the low-power consuming Sleep mode. In
Sleep mode, the 10 MHz main oscillator is turned off,
disabling the RF and baseband circuitry. Data is
retained in the control and FIFO registers and the
transceiver is accessible through the SPI port.
The MRF49XA will not enter Sleep mode if any of the
interrupt remains active, irrespective of the state of the
OSCEN bit in the PMCREG. This way, the
microcontroller can always have a clock signal to
process the interrupt. To prevent high-current
consumption, which results in shorter battery life, it is
highly recommended to process and clear interrupts
before entering Sleep mode. The functions which are
not necessary should be turned off to avoid unwanted
interrupts.
The device has the ability to wake itself up from Sleep
mode through a wake-up timer. The WTSREG sets the
wake-up interval for the MRF49XA. After setting the
wake-up interval, the WUTEN bit (PMCREG<1>)
should be cleared and set at the end of every wake-up
cycle.
The Wake-up Duration Time (WUTIME) is calculated
as shown in Equation 3-4.
EQUATION 3-4:
WUTIME = 1.03 x WTMV<7:0> x 2WTEV<4:0> + 0.5 ms
where:
WTMV<7:0> = Decimal Value between 0 to 255
WTEV<4:0> = Decimal Value between 0 to 29
Note: WUTIME is measured in ms.
The Battery Threshold Detect feature is useful in
monitoring the discharge-sensitive batteries, such as
Lithium cells. The LBDEN bit (PMCREG<2>) is used to
enable or disable the low battery detect feature.
The BCSREG configures the following:
• Output clock frequency
• Low battery detect threshold
The low battery threshold value is programmable from
2.2V to 3.8V and is calculated by using Equation 3-5.
EQUATION 3-5:
Threshold Voltage Value = 2.25 + 0.1 x (LBDVB<3:0>)
To minimize the current consumption, the MRF49XA
supports different power-saving modes, along with an
integrated wake-up timer. Active mode can be
reinitiated by the following ways:
• By applying the wake-up events’ negative logical
pulse on INT pin
• Wake-up timer time-out
• Low supply voltage detection
• On-chip FIFO filled up
• On receiving a request through the serial interface
To make the MRF49XA device enter into Sleep mode,
certain control register values must be initialized. The
sequence to program the control registers for entering
into Sleep and Wake-up modes is as follows:
For Sleep mode:
1.
2.
3.
4.
Check the IRO bit status
Read STSREG
Configure GENCREG
Configure PMCREG for oscillator and clock
buffering
where:
LBDVB<3:0> is the Decimal Value from 0-15
When the battery level falls 50 mV below this value, the
LBTD bit (STSREG<10>) is set, indicating that the
battery level is below the programmed threshold.
The registers associated with power-saving modes
are:
•
•
•
•
•
•
•
STSREG (see Register 2-1)
GENCREG (see Register 2-2)
TXCREG (see Register 2-4)
RXCREG (see Register 2-7)
PMCREG (see Register 2-13)
WTSREG (see Register 2-14)
BCSREG (see Register 2-16)
For Wake-up mode:
1.
2.
3.
Enter in TX/RX mode or
Enable crystal or
Set the INT pin
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 65
MRF49XA
3.17
TX Register Buffered Data
Transmission
In Data Transmission mode (enabled by the TXDEN bit
(GENCREG<7>)), the TX data is clocked into one of
the two 8-bit data registers. The transmitter starts to
send the data from the first register (with the given bit
rate) when the TXCEN bit (PMCREG<5>) is set. The
initial value of the data registers (0xAA) can be used to
generate preamble. During this mode, the SDO pin is
monitored to check whether the register is ready (SDO
is high) to receive the next byte from the
microcontroller. The block diagrams of the Transmit
register, before and during transmit, are shown in
Figure 3-14 and Figure 3-15, respectively.
FIGURE 3-14:
The transmitter FSK modulation parameters are used
for calculating the resulting output frequency, as shown
in Equation 3-6.
EQUATION 3-6:
fFSKOUT = f0 + (-1)SIGN x (MB + 1) x (15 kHz)
where:
f0 is the Channel Center Frequency
(see Register 2-6 for f0 calculation)
MB is the 4-bit Binary Number (MODBW<3:0>)
SIGN = MODPLY XOR FSK
TX REGISTER BLOCK DIAGRAM (BEFORE TRANSMIT)
TXCEN = 0
(Register Initial Fill-up)
SDI
8-Bit Shift Register
(Default: AAh)
SDO
8-Bit Shift Register
(Default: AAh)
SDO
TX_DATA
CLK
Serial Bus Data
SCLK
DS70590C-page 66
SDI
CLK
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
FIGURE 3-15:
TX REGISTER BLOCK DIAGRAM (DURING TRANSMIT)
TXCEN = 1
(During TX)
SDI
8-Bit Shift Register
SEL
10 Y
Bit Rate
SDO
CLK
11
MUX
SEL
1:8
Divider
10
SEL
8-Bit Shift Register
10
SCLK
Y
TX_DATA
SDI
Y
CLK
SDO
11
MUX
11
MUX
Serial Bus Data
© 2009-2011 Microchip Technology Inc.
Note: The data registers’ content is initialized by clearing the TXCEN bit.
Preliminary
DS70590C-page 67
MRF49XA
The device transmit sequence should be performed as
follows:
1.
2.
Enable the TX register by setting TXDEN = 1.
The TX register is automatically filled with
0xAAAA, which can be used to generate
preamble.
3. Enable the transmitter by setting TXCEN = 1.
4. The synthesizer and the PLL turns on, calibrates
itself and the PA is automatically enabled.
5. The TX data transmission starts.
6. On completion of byte transmission, the IRO pin
goes high and the SDO pin goes low
simultaneously. The IRO pulse shows that the
first 8 bits (the first byte by default, 0xAA) have
been transmitted. There are still 8 bits in the
transmit register.
7. The microcontroller recognizes the interrupt and
writes a data byte to the TXBREG.
8. Repeat steps 6 and 7 until the last data byte is
reached.
9. Using the same method, transmit a dummy byte.
The value of this dummy byte can be anything.
10. The next high-to-low transition on the IRO line
(or low-to-high on the SDO pin) shows that the
transmission of the data bytes has ended. The
dummy byte is still in the TX latch.
11. Turn off the transmitter by setting the bit,
TXCEN = 0. This event probably happens while
the dummy byte is being transmitted. Since the
dummy byte contains no useful information, this
corruption will not cause any problem.
12. Clearing the TXDEN bit clears the register
underrun interrupt. The IRO pin goes high and
the SDO pin goes low.
TABLE 3-3:
Mode
Transmit
The transmit sequence is illustrated in Figure 3-16. For
details on transmit pin function configuration, see
Table 3-3. The TXDEN bit is in the GENCREG register
and enables the Transmit Data register.
The transmit sequence can be performed without
sending a dummy byte (step 1), but after loading the
last data byte to the transmit register, the PA turn off
should be delayed for at least 16 bits time. The
microcontroller clock source (if the clock is not supplied
by the transceiver) should be stable enough over
temperature and voltage ranges to ensure this
minimum delay under all operating circumstances.
When the dummy byte is used, the whole process is
driven by interrupts. Changing the TX data rate has no
effect on the algorithm and no accurate delay
measurement is needed. Figure 3-17 shows the
multi-byte transmit write sequence.
The registers associated with transmission are:
•
•
•
•
•
STSREG (see Register 2-1)
GENCREG (see Register 2-2)
TXCREG (see Register 2-4)
TXBREG (see Register 2-5)
PMCREG (see Register 2-13)
TRANSMIT PIN FUNCTION VS. OPERATION MODE
Bit Setting
Function
Pin 6
Pin 7
TXDEN = 0
Internal TX Data register disabled
TX data input
Not used
TXDEN = 1
Internal TX Data register enabled
FSEL input
(TX Data register can be
accessed)
DS70590C-page 68
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
FIGURE 3-16:
TX REGISTER USAGE
Do not switch the TXCEN off here, because the TX
Byte 1 is not transmitted out, it is only stored in the
internal register
Enabling the transmitter preloads the TX latch with
0xAAAA
SPI
Commands
GENCREG
(CS, SCK, SDI)
TXDEN = 1
TX Latch
TX Latch
TX Byte 1
Dummy
TX Byte
PMCREG
TXCEN = 1
PMCREG
TXCEN = 0
GENCREG
TXDEN = 0
TXCEN
Enable
Synthesizer/PA
Synt.
PA
Ttx_xtal_on(1)
0xAA
TX Data
0xAA
TX Byte1
Fraction of the dummy byte
IRO
SDO(2)
Note 1: Ttx_xtal_on is the start-up time of PLL + PA with a running crystal oscillator.
2: SDO is a tri-state of CS.
FIGURE 3-17:
MULTIPLE BYTE WRITE WITH TRANSMIT REGISTER
CS
SCK
TX BYTE 2
TX BYTE 1
SDI
TX BYTE n
Transmit Register Write
SDO
(Register interrupt in TX mode*)
* The device is in Transmit (TX) mode when the RXCEN bit is cleared using the PMCREG.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 69
MRF49XA
3.18
RX FIFO Buffered Data Read
the device on the rising edge of the clock on the SCK
pin. The serial interface is initialized every time if the
CS signal is high. Figure 3-18 shows a simple receiver
FIFO read over SPI lines.
In the Receive Operating mode, the incoming data is
clocked into a 16-bit FIFO buffer. The receive pin
function configuration required for the FIFO operation
is given in Table 3-4. The FIFOEN bit is in the
GENCREG register and enables the receive FIFO. The
receiver starts to fill the FIFO when the FINTDIO bit and
the synchronous pattern recognition circuit indicates
the potential real incoming data. This prevents the
FIFO from being filled with noise and avoids the
overloading on the external microcontroller.
In general, MRF49XA registers are read only. The
RXFIFO and the chip status can be read. During write
only appropriate byte is written to the desired register.
Hence it is not desired to read/write all registers and
there is no way reading back any of the other registers.
To test the SPI interface lines, the best is to set the LBD
(Low Battery Detector) threshold below the actual VDD
and the device must generate an interrupt.
The internal synchronous pattern and the pattern
length are user-programmable. If the Chip Select (CS)
pin is low, the data bits on the SDI pin are shifted into
FIGURE 3-18:
RECEIVER FIFO READ
CS
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
SCK
SDI
Received Bits Out
SDO
TXRXFIFO
MSB
LSB
(TX/RX mode)
Note: The transceiver is in Receive (RX) mode when the RXCEN bit is set using the PMCREG .
DS70590C-page 70
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
3.18.1
INTERRUPT MODE
3.18.2
The user can define the FIFO interrupt level (the
number of received bits) which generates the FINT
when the level is exceeded. In this case, the Status bits
report the changed FIFO status.
POLLING MODE
When the FSEL signal is low, the FIFO output is
connected directly to the SDO pin and its contents are
clocked out by the SCK pin. Set the FIFO interrupt level
to 1. In this case, as long as FINT indicates received
bits in the FIFO, the microcontroller continues to take
the bits away. When FINT goes low, no more bits need
to be taken.
An SPI read command (Receiver FIFO Read
Command) is also available to read out the contents of
the FIFO. See Figure 3-19 for a simple receiver FIFO
read, in Polling mode, on SPI lines.
TABLE 3-4:
Mode
Receive
FIGURE 3-19:
RECEIVE PIN FUNCTION VS. OPERATION MODE
Bit Setting
Function
Pin 6
Pin 7
FIFOEN = 0
Receiver FIFO Disabled
RX Data Output
RX Data Clock Output
FIFOEN = 1
Receiver FIFO Enabled
FSEL Input
(RX data FIFO can be
accessed)
FINT Output
FIFO READ EXAMPLE WITH FINT POLLING
CS
0
1
2
3
4
SCK
FSEL
FIFO Read Out
SDO
FIFO OUT
FO + 1
FO + 2
FO + 3
FO + 4
FINT
The registers associated with reception are:
Note:
During FIFO access, fSCK cannot be
higher than fref/4, where fref is the crystal
oscillator frequency. If the duty cycle of
the clock signal is not 50%, the shorter
period of the clock pulse should be at
least 2/fref.
© 2009-2011 Microchip Technology Inc.
•
•
•
•
•
STSREG (see Register 2-1)
GENCREG (see Register 2-2)
RXCREG (see Register 2-7)
FIFORSTREG (see Register 2-10)
PMCREG (see Register 2-13)
Preliminary
DS70590C-page 71
MRF49XA
3.19
RX-TX Frequency Alignment
Method
The RX-TX frequency offset occurs due to the
differences in the actual reference frequency. To
minimize this error, the same crystal type and the same
PCB layout should be used for the crystal placement on
the RX and TX PCBs. Also, see Section 3.6, Crystal
Selection Guidelines.
To verify the possible RX-TX offset, it is recommended
to measure the CLK output of both transceivers with a
high level of accuracy. Do not measure the output at the
RFXTL pin as the measurement process itself might
change the reference frequency. As the carrier
frequencies are derived from the reference frequency,
having identical reference frequencies, and nominal
frequency settings at the TX and RX side, there should
be no offset if the CLK signals have identical
frequencies.
The actual RX-TX offset can be monitored by using the
AFC status data included in the STSREG of the
receiver. By reading out the STSREG, the actual
measured offset frequency can be reported. In order to
get accurate values, the AFC has to be disabled during
the read by clearing the FOFEN bit in AFCCREG.
The registers associated with RX-TX alignment
procedures are:
•
•
•
•
STSREG (see Register 2-1)
AFCCREG (see Register 2-3)
RXCREG (see Register 2-7)
PMCREG (see Register 2-13)
The crystal oscillator load capacitor bank value is to
fine-tune the oscillator and minimize the offset. So the
process is to measure the clock output and parallel
change the value to minimize the offset.
DS70590C-page 72
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
4.0
APPLICATION DETAILS
The application circuit of MRF49XA with a balun circuit
is shown in Figure 4-1.
FIGURE 4-1:
APPLICATION CIRCUIT
VDD
C1
2 .2 u F
IN T /D IO *
RC7
SDI
RC6
SCK
RC5
CS
RC4
RC3
IR O
RC2
F S K /D A T A /F S E L *
RC1
R C L K O U T /F C A P /F IN T *
RC0
C LK O U T*
OSC1
_____
M C LR
1
16
2
15
3
14
4
5
MRF49XA
P IC ® M C U
SDO
C3
0 .0 1 u F
C2
(see
Table 2-2)
C4*
2 .2 n F
13
B a lu n
12
6
11
7
10
8
9
50 O hm Loop
A n te n n a
RESET*
X1
10 M H z
* C o n n e c tio n s a re o p tio n a l.
4.1
Antenna/Balun
A balun circuit for a 50Ω antenna is shown in
Figure 4-2. If low tolerance components (i.e., ±5%) are
used with an appropriate ground, the impedance
remains close to the 50Ω measurement.
FIGURE 4-2:
BALUN CIRCUIT
+3.3V
L1
C5
C6
J1
50 Ω ANT
RFN
L2
L3
RFP
C7
© 2009-2011 Microchip Technology Inc.
Freq.
L1
868 MHz
390 nH
33 nH
47 nH
2.7 pF
68 pF
5.1 pF
433 MHz
100 nH
8.2 nH
22 nH
1.2 pF
27 pF
2.7 pF
915 MHz
100 nH
8.2 nH
22 nH
1.2 pF
27 pF
2.7 pF
Preliminary
L2
L3
C5
C6
C7
DS70590C-page 73
MRF49XA
4.2
Antenna Design Considerations
The MRF49XA is designed to drive a differential output,
such as a dipole antenna or a loop antenna. The loop
antenna is ideally suited for applications where
compact size is required. The dipole is typically not a
good option for compact designs due to its inherent
size at resonance, and its space requirements around
the ground plane, to be an efficient antenna. A
monopole antenna can be used, along with a balun, or
by using the matching circuit.
TABLE 4-1:
RF Transmitter Matching
The RF pins are of high impedance and differential
value. The optimum differential load for the RF port at
a given frequency band is shown in Table 4-1.
These load values in the table are expected by the RF
port pins to have as an antenna load for maximum
power transfer. Antennas that are suited for such
values would be a Loop, Dipole and Folded Dipole. For
all antenna applications, either a bias, choke inductor
or coils must be included during transmission since the
RF outputs are of open-collector type.
FREQUENCY BAND – ANTENNA ADMITTANCE/IMPEDANCE
MRF49XA
4.4
4.3
Admittance (ms)
Impedance (Ω)
433 MHz
2–j5.9
52+j152
62
868 MHz
1.2–j11.9
7.8+j83
15.4
915 MHz
1.49–j12.8
9+j77
13.6
General PCB Layout Design
The guidelines in this section help the users in
high-frequency PCB layout design.
The printed circuit board is usually comprised of two or
four basic FR4 layers.
The two-layer printed circuit board has mixed
signal/power/RF and common ground routed in both
the layers.
FIGURE 4-3:
Inductance (nH)
The four-layer printed circuit board is comprised of the
following layers:
•
•
•
•
Signal layout
RF ground
Power line routing
Common ground
The four-layer PCB is shown in Figure 4-4.
TWO BASIC COPPER FR4 LAYERS
Signal/Power/RF and
Common Ground
Dielectric Constant = 4.5
Signal/Power/RF and
Common Ground
FIGURE 4-4:
FOUR BASIC COPPER FR4 LAYERS
Signal Layout
Dielectric Constant = 4.5
RF Ground
Dielectric Constant = 4.5
Power Line Routing
Dielectric Constant = 4.5
Ground
DS70590C-page 74
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
The following guidelines explain the requirements of
the above mentioned layers.
• It is important to keep the original PCB thickness,
since any change will affect antenna performance
(see total thickness of dielectric) or microstrip
lines’ characteristic impedance.
• For good transmit and receive performance, the
trace lengths at RF pins must be kept as short as
possible. Using small, surface mount components
(in 0402/0603 package) yields good performance
and keeps the RF circuit small. RF connections
should be short and direct.
• Except for the antenna layout, avoid sharp
corners since they can act as an antenna. Round
corners will eliminate possible future EMI
problems.
• Digital lines are prone to be very noisy when
handling periodic waveforms and fast
clock/switching rates. Avoid RF signal layout
close to any of the digital lines.
• A VIA filled ground patch underneath the IC
transceiver is mandatory.
• Power supply must be distributed to each pin in a
star topology and low-ESR capacitors must be
placed at each pin for proper decoupling noise.
• Thorough decoupling on each power pin is
beneficial for reducing in-band transceiver noise,
particularly when this noise degrades performance. Usually, low value caps (27 pF – 47 pF)
combined with large value caps (100 nF) will
cover a large spectrum of frequency.
• Passive component (inductors) should be in the
high-frequency category and the Self Resonant
Frequency (SRF) should be at least two times
higher than the operating frequency.
© 2009-2011 Microchip Technology Inc.
• The additional trace length affects the crystal
oscillator by adding parasitic capacitance to the
overall load of the crystal. To minimize this, place
the crystal as close as possible to the RF device.
• Setting short and direct connections between the
components on board minimizes the effects of
“frequency pulling” that might be introduced by
stray capacitance. It even allows the internal load
capacitance of the chip to be more effective in
properly loading the crystal oscillator circuit.
• Long run tracks of clock signal may radiate and
cause interference. This can degrade receiver
performance and add harmonics or unwanted
modulation to the transmitter.
• Keep clock connections as short as possible and
surround the clock trace with an adjacent ground
plane pour. Pouring helps in reducing any
radiation or crosstalk due to long run traces of the
clock signal.
• Low value decoupling capacitors, typically 0.01 μF
– 0.1 μF, should be placed for VDD of the chip and
for bias points of the RF circuit.
• High value decoupling capacitors, typically 2.2 μF
– 10 μF, should be placed at the point where
power is applied to the PCB.
• Power supply bypassing is necessary. Poor
bypassing contributes to conducted interference
which can cause noise and spurious signals to
couple into the RF sections, significantly reducing
performance.
Preliminary
DS70590C-page 75
MRF49XA
4.5
MRF49XA Schematic and Bill of
Materials
4.5.1
SCHEMATIC
FIGURE 4-5:
MRF49XA SCHEMATIC
+3.3V
C1
RSSIO
C2
0.01 uF
C3
2.2 uF
6.3V
C4
1000 pF
+3.3V
INT/DIO
L1
U1
MRF49XA
SDI
SCK
__
CS
SDO
__
IRO
__
FSEL
FINT
TP1
CLK
TP2
GND
1
2
3
4
5
6
7
89
C5
C6
J1
50Ω ANT
__
16
SDI
INT/DIO
15
SCK
RSSIO
__
14
VDD
CS
13
SDO
RFN
__
12
IRO
RFP
___
11
FSK/DATA/FSEL
VSS
____
10
RCLK
OUT/FCAP/FINT RESET
CLKOUT
RFXTL/EXTREF
L2
L3
C7
X1
10 MHz
___
RESET
Freq.
DS70590C-page 76
C1
L1
L2
390 nH
33 nH
L3
C5
C6
47 nH
2.7 pF
68 pF
C7
433 MHz
220 pF
868 MHz
47 pF
100 nH
8.2 nH
22 nH
1.2 pF
27 pF
2.7 pF
915 MHz
33 pF
100 nH
8.2 nH
22 nH
1.2 pF
27 pF
2.7 pF
Preliminary
5.1 pF
© 2009-2011 Microchip Technology Inc.
MRF49XA
4.5.2
BILL OF MATERIALS
TABLE 4-2:
MRF49XA: 433 MHz BILL OF MATERIALS
Designator
Value
C1
200 pF
Capacitor, Ceramic, 50V, C0G,
SMT 0603
Murata
GRM1885C1H201JA01D
C5
2.7 pF
Capacitor, Ceramic, 50V, C0G,
SMT 0603
Murata
GRM1885C1H2R7CZ01D
C6
68 pF
Capacitor, Ceramic, 50V, C0G,
SMT 0603
Murata
GRM1885C1H680JA01D
C7
5.1 pF
Capacitor, Ceramic, 50V, C0G,
SMT 0603
Murata
GRM1885C1H5R1DZ01D
L1
390 nH
Inductor, Ceramic, 5%, SMT 0603
Murata
LQW18ANR39J00D
L2
33 nH
Inductor, Multilayer, 5%, SMT 0603
TDK Corporation MLG1608B33NJ
L3
47 nH
Inductor, Multilayer, 5%, SMT 0603
TDK Corporation MLG1608B47NJ
C4
1000 pF
Capacitor, Ceramic, 50V, 10%,
SMT 0603, X7R
Murata
GRM188R71H102KA01D
C2
10000 pF
Capacitor, Ceramic, 50V, 10%,
SMT 0603, X7R
Murata
GRM188R71H103KA01D
Kemet
T491A225K010AT
C3
Description
2.2 μF, 10V Capacitor, Tantalum, 10%,
SMT 3216-18 (A)
U1
—
X1
10 MHz
Manufacturer
Manufacturer PN
MRF49XA Transceiver
Microchip
MRF49XA-I/ST
Crystal, ±10 ppm, 10 pF,
SMT 5 x 3.2 mm
Abracon
ABM3B-10.000MHZ-12-R8
0-B-1-U-T
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 77
MRF49XA
TABLE 4-3:
MRF49XA: 868/915 MHz BILL OF MATERIALS
Designator
Value
C1
33 pF
Capacitor, Ceramic, 50V, C0G,
SMT 0603
Murata
GRM1885C1H330JA01D
C5
1.2 pF
Capacitor, Ceramic, 50V, C0G,
SMT 0603
Murata
GRM1885C1H1R2CZ01D
C6
27 pF
Capacitor, Ceramic, 50V, C0G,
SMT 0603
Murata
GRM1885C1H270JA01D
C7
2.7 pF
Capacitor, Ceramic, 50V, C0G,
SMT 0603
Murata
GRM1885C1H2R7CZ01D
L1
100 nH
Inductor, Multilayer, 5%, SMT 0603
L2
8.2 nH
Inductor, Multilayer, 5%, SMT 0603
TDK Corporation MLG1608B8N2D
L3
22 nH
Inductor, Multilayer, 5%, SMT 0603
TDK Corporation MLG1608B22NJ
C4
1000 pF
Capacitor, Ceramic, 50V, 10%,
SMT 0603, X7R
Murata
GRM188R71H102KA01D
C2
10000 pF
Capacitor, Ceramic, 50V, 10%,
SMT 0603, X7R
Murata
GRM188R71H103KA01D
Kemet
T491A225K010AT
C3
2.2 μF, 10V Capacitor, Tantalum, 10%,
SMT 3216-18 (A)
U1
—
X1
10 MHz
DS70590C-page 78
Description
Manufacturer
Manufacturer PN
TDK Corporation MLG1608BR10J
MRF49XA Transceiver
Microchip
MRF49XA-I/ST
Crystal, ±10 ppm, 10 pF,
SMT 5 x 3.2 mm
Abracon
ABM3B-10.000MHZ-12-R80B-1-U-T
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
5.0
ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings(†)
Temperature under bias ........................................................................................................................... -40°C to +85°C
Storage temperature .............................................................................................................................. -55°C to +125°C
Lead temperature (soldering, max 10s) ............................................................................................................... +260°C
Voltage on VDD with respect to VSS ............................................................................................................... -0.3V to 6V
Voltage on any combined digital and analog pin with respect to VSS
(except RFP, RFN and VDD) ........................................................................................................... -0.3V to (VDD + 0.3V)
Voltage on open-collector outputs (RFP, RFN)(1) ........................................................................... -0.5V to (VDD + 1.5V)
Input current into pin (except VDD and VSS).......................................................................................... -25 mA to 25 mA
Electrostatic discharge with human body model .................................................................................................... 1000V
Note:
At maximum, voltage on RFP and RFN cannot be higher than 7V.
† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the device at those or any other conditions above those
indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 79
MRF49XA
TABLE 5-1:
RECOMMENDED OPERATING CONDITIONS
Parameters
Min
Typ
Max
Unit
Operating Temperature
-40
—
+85
°C
Supply Voltage for RF, Analog and Digital
Circuits
2.2
—
3.8
V
Supply Voltage for Digital I/O
2.2
3.3
3.8
V
DC Voltage on Open-Collector Outputs
(RFP, RFN)(1,2)
VDD–1.5
—
VDD+1.5
V
AC Peak Voltage on Open-Collector
Outputs (RFP, RFN)(1)
VDD–1.5
—
VDD+1.5
V
Note 1:
2:
At minimum, VDD – 1.5V cannot be lower than 1.2V.
At maximum, VDD + 1.5V cannot be higher than 5.5V.
CURRENT CONSUMPTION(1)
TABLE 5-2:
Chip mode
Condition
Min
Typ
Max
Unit
Sleep
Sleep clock disabled, all blocks disabled
—
0.3
1
μA
Idle
Oscillator and baseband enabled, clock
output disabled
—
0.6
1.2
mA
TX
TX
RX
Power output – 0 dBm, 50Ω load, 433 MHz
—
15
—
mA
868 MHz
—
16
—
mA
915 MHz
—
17
—
mA
At maximum output power, 433 MHz
—
22
26
mA
868 MHz
—
23
27
mA
915 MHz
—
24
28
mA
433 MHz
—
11
13
mA
868 MHz
—
12
14
mA
—
13
15
mA
Low Battery Voltage Detector
Current Consumption
915 MHz
—
—
0.5
1.7
μA
Wake-up Timer Current
Consumption
—
—
1.5
3.5
μA
Note 1:
Typical Values: TA = 25°C, VDD = 3.3V.
I/O PIN INPUT SPECIFICATIONS(1)
TABLE 5-3:
Symbol
Characteristic
VIL
Input Low Voltage
VIH
Input High Voltage
(2)
Condition
Min
Typ
Max
Unit
—
—
—
0.3xVDD
V
—
0.7xVDD
—
—
V
IIL
Input Low Leakage Current
VIL = 0V
-1
—
1
μA
IIH
Input High Leakage Current
VIH = VDD, VDD = 3.8V
-1
—
1
μA
VOL
Digital Low Output Voltage
lOL = 2 mA
—
—
0.4
V
VOH
Digital Low Output
IOH = -2 mA
VDD–0.4
—
—
V
VLBTD
Low Battery Threshold Detect
Programmable in 0.1V
steps
2.25
—
3.75
V
Note 1:
2:
Typical Values: TA = 25°C, VDD = 3.3V.
Negative current is defined as the current sourced by the pin.
DS70590C-page 80
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
TABLE 5-4:
RECEIVER AC CHARACTERISTICS(1)
Parameters
Receiver Sensitivity
Condition
Min
Typ
Max
Unit
(2)
—
-112
—
dBm
(2)
—
-110
—
dBm
(2)
915 MHz band
—
-109
—
dBm
LNA: High Gain
0
—
—
dBm
433 MHz band
868 MHz band
Maximum RF Input
Power
RF Input Capacitance
—
—
1
—
pF
Receiver Spurious
Emission
—
—
—
-60
dBm
mode 0
—
67
—
kHz
Mode 1
—
134
—
kHz
Mode 2
—
200
—
kHz
Mode 3
—
270
—
kHz
Mode 4
—
340
—
kHz
Receiver BW
Mode 5
RSSI Range
RSSI Error
—
400
—
kHz
—
—
46
—
dB
—
—
±6
—
dB
RSSI Power Supply
Dependency
When input signal level is lower than
-54 dBm and greater than -100 dBm
—
+35
—
mV/V
Filter Capacitor for
Analog RSSI
—
1
—
—
nF
RSSI Programmable
Level Steps
—
—
6
—
dB
Digital RSSI
Response Time
Until the RSSI signal goes high after
the input signal exceeds the
preprogrammed limit, CARRSI = 4.7
nF
—
500
—
μs
Input IP3
In band interferers in high bands (868
MHz, 915 MHz)
—
-21
—
dBm
IIP3
(LNA – 6 dB gain)
In band interferers in low band (433
MHz)
—
-15
—
dBm
IIP3
(LNA – 6 dB gain)
Out of band interferers,
l f-fO l > 4 MHz
—
-12
—
dBm
FSK Bit Rate
With internal digital filters supported
by design
0.6
—
115.2
kbps
FSK Bit Rate
With internal analog filters supported
by design
—
—
256
kbps
AFC Locking Range
Δffsk: FSK deviation in the received
signal
—
0.8 – Δffsk
—
—
Note 1:
2:
Typical Values: TA = 25°C, VDD = 3.3V.
BER = 10E – 3, BW = 67 kHz, Δf = 30 kHz, Baud Rate = 1.2 kbps, digital filter with AFC disabled.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 81
MRF49XA
TABLE 5-5:
TRANSMITTER AC CHARACTERISTICS(1)
Parameters
RF Carrier Frequency
Maximum RF Output Power
Condition
Min
Typ
Max
Unit
433 MHz band, 2.5 kHz resolution
430.24
—
439.75
MHz
868 MHz band, 5.0 kHz resolution
860.48
—
879.51
MHz
915 MHz band, 7.5 kHz resolution
900.72
—
929.27
MHz
433 MHz @ 50Ω load
—
7
—
dBm
868 MHz @ 50Ω load
—
5
—
dBm
915 MHz @ 50Ω load
—
5
—
dBm
RF Output Power Control Range In steps of 8
Pmax – 17.5
—
Pmax
dBm
TX Gain Control Resolution
Programmed in 8 steps
—
2.5
—
dB
Harmonic Suppression
At maximum power, 50Ω load
—
—
-35
dBc
Open-Collector Output DC
Current
Programmable
0.5
—
6
mA
Spurious Emission
| f-fsp | > 1 MHz
At maximum power, 50Ω load
—
—
-55
dBc
Output Capacitance (Set by the
Automatic Antenna Tuning
Circuit)
433 MHz band
2
2.6
3.2
pF
868 MHz band
2.1
2.7
3.3
pF
915 MHz band
2.1
2.7
3.3
pF
Quality Factor of the Output
Capacitance
433 MHz band
13
15
17
—
868 MHz band
8
10
12
—
915 MHz band
8
10
12
—
100 kHz from carrier
—
-80
—
dBc/Hz
1 MHz from carrier
—
-103
—
dBc/Hz
Output Phase Noise
FSK Bit Rate
Internal TX Data register
—
—
172
kbps
FSK Bit Rate
TX data connected to the FSK
input
—
—
256
kbps
FSK Frequency Deviation
Programmable in 15 kHz steps
15
—
240
kHz
Note 1:
Typical Values: TA = 25°C, VDD = 3.3V.
TABLE 5-6:
PLL PARAMETERS AC CHARACTERISTICS(1)
Parameters
Condition/Note
Min
Typ
Max
Unit
PLL Reference Frequency
Crystal related timing and frequency parameters change
according to the PLL reference
frequency
9
10
11
MHz
PLL Lock Time
Frequency error <1 kHz after
10 MHz step
—
30
—
μs
PLL Start-up Time
With a running crystal oscillator
and based on the design
—
200
300
μs
Note 1:
Typical Values: TA = 25°C, VDD = 3.3V.
DS70590C-page 82
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
TABLE 5-7:
OTHER TIMING PARAMETERS AC CHARACTERISTICS(1)
Parameters
Condition
Min
Typ
Max
Unit
Transmitter Switch On Time
Synthesizer off, crystal oscillator
on with 10 MHz step
—
250
—
μs
Receiver Switch On Time
Synthesizer off, crystal oscillator
on with 10 MHz step
—
250
—
μs
Transmitter to Receiver Switch
Time
Synthesizer and crystal oscillator
on during TX/RX change with 10
MHz step
—
150
—
μs
Receiver to Transmitter Switch
Time
Synthesizer and crystal oscillator
on during RX/TX change with 10
MHz step
—
150
—
μs
Crystal Load Capacitance (See
Crystal Selection Guide)
Programmable in 0.5 pF steps,
tolerance ±10%
8.5
—
16
pF
Crystal Oscillator Start-up Time
Default capacitance bank setting,
crystal ESR <50Ω. Crystal load
capacitance = 16 pF.(2)
—
2
7
ms
Internal POR Time-out
After VDD has reached 90% of the
final value(3)
—
—
100
ms
Wake-up Timer Clock Accuracy
Crystal oscillator must be enabled
to ensure proper calibration at the
start-up(2)
—
±10
—
%
—
—
—
2
pF
—
—
10
ns
Digital Input Capacitance
Digital Output Rise/Fall Time
Note 1:
2:
3:
15 pF pure capacitive load
Typical Values: TA = 25°C, VDD = 3.3V.
The crystal oscillator start-up time depends on the capacitance seen by the oscillator. Low capacitance and
low-ESR crystal are recommended with low parasitic PCB layout design.
During the Power-on Reset period, commands are not accepted by the chip. In case of Software Reset (see
WTSREG (Register 2-14)), the Reset time-out is typically 0.25 ms.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 83
MRF49XA
5.1
Timing Specification and Diagram
TABLE 5-8:
SPI TIMING SPECIFICATION
Symbol
Parameter
Minimum Value (ns)
tCH
Clock High Time
25
tCL
Clock Low Time
25
tSS
Select Setup Time (CS falling edge to SCK rising edge)
10
tSH
Select Hold Time (SCK falling edge to CS rising edge)
10
tSHI
Select High Time
25
tDS
Data Setup Time (SDI transition to SCK rising edge)
5
tDH
Data Hold Time (SCK rising edge to SDI transition)
5
tOD
Data Delay Time
10
FIGURE 5-1:
SPI TIMING DIAGRAM
tSS
tSHI
CS
tCD
tCH
tSH
tCL
SCK
tDS
SDI
SDO
tDH
BIT 15
TXRXFIFO
BIT 14
POR
BIT 13
BIT 8
TXOWRXOF
BIT 7
BIT 1
DQDO
OFFSB(0)
BIT 0
FIFO OUT
ATRSSI
DS70590C-page 84
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
5.2
Typical Performance
Characteristics
CHANNEL SELECTIVITY AND BLOCKING(1,2)
FIGURE 5-2:
80
70
Suppression (dB)
60
50
40
30
20
434 MHz
10
868 MHz
ETSI
0
0
1
2
3
4
5
6
7
8
9
10
11
12
CW Interferer Offset with respect to Carrier (MHz)
Note 1:
2:
LNA gain maximum, filter bandwidth 67 kHz, data rate 9.6 kbps, AFC switched off, FSK
deviation ±45 kHz, VDD = 2.7V.
The ETSI limit given in the figure is drawn by taking -106 dBm at 9.6 kbps typical sensitivity
into account and corresponds to receiver class 2 requirements.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 85
MRF49XA
FIGURE 5-3:
BER CURVES IN 433 MHz BAND
BER Curves in 433 MHz Band
1.0E+00
1.0E-01
BER
1.0E-02
1.0E-03
1.0E-04
1.2k
9.6k
19.2k
115.2k
1.0E-05
1.0E-06
-120
-115
-110
-105
-100
-95
-90
Input Power (dBm)
FIGURE 5-4:
BER CURVES IN 868 MHz BAND
BER Curves in 868 MHz Band
1.0E+00
1.0E-01
BER
1.0E-02
1.0E-03
1.0E-04
1.2k
9.6k
19.2k
115.2k
1.0E-05
1.0E-06
-115
-110
-105
-100
-95
-90
-85
Input Power (dBm)
DS70590C-page 86
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
Table 5-9 shows the optimal receiver BBBW and
transmitter deviation frequency (ΔfFSK) settings for
different data rates, considering no TX/RX offset
frequency. If the TX/RX offset (for example, due to
crystal tolerances) has to be taken into account,
increase the BW accordingly.
TABLE 5-9:
Baud
Rate
RX BW AND TX DEVIATION FREQUENCY FOR DIFFERENT BAUD RATES
1.2 kbps
2.4 kbps
4.8 kbps
9.6 kbps
19.2 kbps
38.4 kbps
57.6 kbps
115.2 kbps
BW
in kHz
BW – 67
BW – 67
BW – 67
BW – 67
BW – 67
BW – 134
BW – 134
BW – 200
ΔTX
in kHz
ΔfFSK – 45
ΔfFSK – 45
ΔfFSK – 45
ΔfFSK – 45
ΔfFSK – 45
ΔfFSK – 90
ΔfFSK – 90
ΔfFSK – 120
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 87
MRF49XA
FIGURE 5-5:
RECEIVER SENSITIVITY OVER AMBIENT TEMPERATURE
(433 MHz, 2.4 kbps, ΔfFSK: 45 kHz, BW: 67 kHz)
Receiver Sensitivity over Ambient Temperature for 433 MHz
-100
Power Level (dBm)
-103
2.2V
-106
2.7V
3.3V
-109
3.8V
-112
-115
-50
-25
0
25
50
75
100
Temperature (°C)
FIGURE 5-6:
RECEIVER SENSITIVITY OVER AMBIENT TEMPERATURE
(868 MHz, 2.4 kbps, ΔfFSK: 45 kHz, BW: 67 kHz)
Receiver Sensitivity over Ambient Temperature for 868 MHz
-100
Power Level (dBm)
-103
2.2V
-106
2.7V
3.3V
-109
3.8V
-112
-115
-50
-25
0
25
50
75
100
Temperature (°C)
DS70590C-page 88
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
6.0
PACKAGING INFORMATION
6.1
Package Marking Information
16-Lead TSSOP
Example
XXXXXXXX
YYWW
NNN
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
49XA/ST e3
0910
017
Product-specific information
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
This package is Pb-free. The Pb-free JEDEC designator ( e3 )
can be found on the outer packaging for this package.
In the event, the full Microchip part number cannot be marked on one line, it
will be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 89
MRF49XA
6.2
Package Details
This section provides the technical details of the
packages.
16-Lead Plastic Thin Shrink Small Outline (ST) – 4.4 mm Body [TSSOP]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
DS70590C-page 90
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
16-Lead Plastic Thin Shrink Small Outline (ST) – 4.4 mm Body [TSSOP]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 91
MRF49XA
16-Lead Plastic Thin Shrink Small Outline (ST) – 4.4 mm Body [TSSOP]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
DS70590C-page 92
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
APPENDIX A:
READ SEQUENCE
AND PACKET
STRUCTURES
Figure 1 shows the STSREG read sequence with FIFO
read as an example.
FIGURE A-1:
STSREG READ SEQUENCE
CS
1
0
2
3
4
5
6
7
8
9
11
10
12
14
13
15
17
16
SCK
Command
SDI
Interrupt Bits Out
(1)(2)(3)
SDO
Status Bits Out
(1,2,3)
POR
TXRXFIFO
TXOWR
XOF
FIFO Out
(1,2,3)
WUTI
NT
LCE
XINT
LBTD
FIFO
EM
ATRS
SI
DQDO
CLKRL
AFCCT
OFFSV
OFFSB
<3>
OFFSB
<2>
OFFSB
<1>
OFFSB
<0>
FO
FO+1
FO+2
(Sign)
(Latched) (Latched) (Latched) (Latched) (Latched)
Note: 1. Applicable when the RXCEN bit is set using the PMCREG.
2. Applicable when the RXCEN bit is cleared using the PMCREG.
3. These bits are internally latched and the other bits are only multiplexed out.
TABLE A-1:
Length
Minimum Length
RECOMMENDED FIFO PACKET STRUCTURES
Preamble
Synchronous Word/Network ID
Payload
CRC
4-8 bits (0x0A or 0x05)
0xD4 (programmable)
—
4-bit-1 byte
0x2DD4 (D4 is programmable)
—
2 bytes
Recommended Length 8-12 bits (e.g., 0xAA or 0x55)
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 93
MRF49XA
NOTES:
DS70590C-page 94
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
APPENDIX B:
REVISION HISTORY
Revision A (March 2009)
This is the initial released version of this document.
Revision B (June 2009)
Major updates are done throughout the document.
Revision C (November 2011)
Minor corrections such as figures, language and
formatting updates are incorporated throughout the
document.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 95
MRF49XA
NOTES:
DS70590C-page 96
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
INDEX
F
A
Absolute Maximum Ratings ................................................ 79
AC Characteristics
Other Timing Parameters............................................ 83
PLL Parameters .......................................................... 82
Receiver...................................................................... 81
Transmitter.................................................................. 82
Antenna Design Considerations ......................................... 74
Antenna/Balun .................................................................... 73
Automatic Frequency Control (AFC) ............................. 14, 50
FIFO Interrupt ..................................................................... 11
Frequency Shift Keying
Data ............................................................................ 11
FIFO Select ................................................................ 11
Functional Description ........................................................ 43
G
General PCB Layout Deign ................................................ 74
H
Hardware Description ........................................................... 9
B
I
Baseband Features............................................................... 3
Baseband/Data Filtering ..................................................... 56
Bill of Materials.................................................................... 77
Block Diagrams
AFC Circuit for Frequency Offset Correction .............. 51
Analog RSSI Voltage vs. RF Input Power................... 15
Application Circuit ....................................................... 73
Balun Circuit................................................................ 73
DIO Logic .................................................................... 58
Four Basic Copper FR4 Layers .................................. 74
Functional Node............................................................ 8
Logic Connection Between Power Control Bits .......... 63
MCU to MRF49XA Interface ......................................... 8
MRF49XA Architectural .............................................. 10
MRF49XA Interrupt Generation Logic......................... 55
RESET Pin Internal Connection.................................. 45
Two Basic Copper FR4 Layers ................................... 74
TX Register Before Transmit ...................................... 66
TX Register During Transmit ...................................... 67
I/O Pin Input Specifications................................................. 80
Initialization ......................................................................... 52
Internet Address ................................................................. 99
Interrupt .............................................................................. 12
Interrupt Request Output .................................................... 11
Interrupts ............................................................................ 52
Clearing ...................................................................... 53
LBTD .......................................................................... 53
LCEXINT .................................................................... 53
POR............................................................................ 53
Setting ........................................................................ 53
TXOWRXOF............................................................... 53
TXRXFIFO.................................................................. 53
WUTINT...................................................................... 53
C
M
Clock Output ....................................................................... 11
Clock Recovery Circuit (CLKRC) ........................................ 14
Crystal Oscillator ................................................................. 14
Crystal Oscillator and Clock Output .................................... 47
Crystal Selection Guidelines ............................................... 49
Current Consumption .......................................................... 80
Customer Change Notification Service ............................... 99
Customer Notification Service............................................. 99
Customer Support ............................................................... 99
Memory Organization ......................................................... 18
Microchip Internet Web Site................................................ 99
D
Data
Data In ........................................................................ 11
Data Out...................................................................... 11
Data Filtering and Clock Recovery ..................................... 14
Analog Operation ........................................................ 57
Digital Operation ......................................................... 57
Data Indicator Output (DIO) ................................................ 15
Data Quality Indicator (DQI).......................................... 15, 58
Data Validity Blocks
Data Indicator Output.................................................. 15
Data Quality Indicator ................................................. 15
Receive Signal Strength Indicator............................... 15
E
Electrical Characteristics..................................................... 79
Errata .................................................................................... 5
Examples
Frequency Deviation and BBBW Calculation.............. 56
External Reference Input .................................................... 12
© 2009-2011 Microchip Technology Inc.
L
Low Duty Cycle Mode................................................... 16, 64
Low Noise Amplifier (LNA).................................................. 13
Low-Battery Voltage Detector............................................. 16
O
Output
Filter Capacitor ........................................................... 11
P
Packaging
Details......................................................................... 90
Marking....................................................................... 89
Packaging Information ........................................................ 89
Performance Characteristics
BER Curves
In 433 MHz Band................................................ 86
In 868 MHz Band................................................ 86
Channel Selectivity and Blocking ............................... 85
Receiver Sensitivity Over Ambient Temperature
At 433 MHz......................................................... 88
At 868 MHz......................................................... 88
Phase Locked Loop (PLL) ............................................ 14, 48
Pin Description.................................................................... 11
Pin Diagram .......................................................................... 4
Pins
CLKOUT ..................................................................... 11
CS............................................................................... 11
DATA .......................................................................... 11
FSK/DATA/FSEL ........................................................ 11
INT/DIO ...................................................................... 12
IRO ............................................................................. 11
RCLKOUT/FCAP/FINT............................................... 11
Preliminary
DS70590C-page 97
MRF49XA
RESET ........................................................................ 12
RFN............................................................................. 12
RFP ............................................................................. 12
RFXTL/EXTREF ......................................................... 12
RSSIO......................................................................... 12
SCK............................................................................. 11
SDI .............................................................................. 11
SDO ............................................................................ 11
VDD.............................................................................. 12
VSS .............................................................................. 12
Power and Low Noise Amplifiers ........................................ 47
Power Management ............................................................ 61
Power-Saving Modes
Low Battery Voltage Detector ..................................... 16
Low Duty Cycle Mode ................................................. 16
Wake-up Timer ........................................................... 16
Programmable Synchronous Byte ...................................... 59
R
Reader Response ............................................................. 100
Receive FIFO ...................................................................... 17
Receive Signal Strength Indicator (RSSI) ........................... 15
Received Signal Strength Indicator (RSSI) ......................... 59
Recommended Operating Conditions ................................. 80
Recovery Clock Output ....................................................... 11
Register Map....................................................................... 42
Registers
AFCCREG (Automatic Frequency Control Configuration)
22
BBFCREG (Baseband Filter Configuration)................ 29
BCSREG (Battery Threshold Detect and Clock Output
Value Set) ........................................................... 40
CFSREG (Center Frequency Value Set) .................... 26
DCSREG (Duty Cycle Value Set) ............................... 39
DRSREG (Data Rate Value Set) ................................ 35
FIFORSTREG (FIFO and Reset Mode Configuration) 32
GENCREG (General Configuration) ........................... 21
PLLCREG (PLL Configuration) ................................... 41
PMCREG (Power Management Configuration) .......... 36
RXCREG (Receive Control)........................................ 27
RXFIFOREG (Receiver FIFO Read)........................... 31
STSREG (STATUS Read) .......................................... 19
SYNBREG (Synchronous Byte Configuration) ........... 34
TXBREG (Transmit Byte)............................................ 25
TXCREG (Transmit Configuration) ............................. 23
WTSREG (Wake-up Timer Value Set)........................ 38
Reset
Power Glitch Reset ..................................................... 44
Power-on Reset .......................................................... 43
RESET Pin.................................................................. 45
Software Reset ........................................................... 45
Reset Mode Selection ......................................................... 33
RESET Pin .......................................................................... 13
Revision History .................................................................. 95
RF Crystal ........................................................................... 12
RF Transmitter Matching..................................................... 74
RF/Analog Features .............................................................. 3
RX FIFO Buffered Data Read ............................................. 70
RX-TX Frequency Alignment Method ................................. 72
Timing Specification.................................................... 84
Synchronous Character Selection ...................................... 33
T
Timing Diagrams
FIFO Read with FINT Polling...................................... 71
FSK Modulated Deviation (Max. TX to RX Offset)...... 57
Low-Power Duty Cycle Mode Sequence .................... 64
Multiple Byte Write with Transmit Register ................. 69
Power-on Reset Example ........................................... 43
Receiver FIFO Read................................................... 70
Sensitive Reset Disabled............................................ 45
Sensitive Reset Enabled............................................. 44
SPI .............................................................................. 84
STSREG Read Sequence .......................................... 93
TX Register Usage ..................................................... 69
Transmit Register ............................................................... 16
TX Register Buffered Data Transmission ........................... 66
Typical Applications .............................................................. 3
V
VDD Line Filtering................................................................ 46
W
Wake-up Timer ................................................................... 16
WWW Address ................................................................... 99
WWW, On-Line Support ....................................................... 5
S
Schematics
MRF49XA ................................................................... 76
Serial Peripheral Interface (SPI) ......................................... 17
Sleep, Wake-up and Battery Operations............................. 65
SPI
DS70590C-page 98
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
THE MICROCHIP WEB SITE
CUSTOMER SUPPORT
Microchip provides online support through our web site
at www.microchip.com. This web site is used as a
means to make files and information easily available to
customers. Accessible by using your favorite Internet
browser, the web site contains the following
information:
Users of Microchip products can receive assistance
through several channels:
• Product Support – Data sheets and errata,
application notes and sample programs, design
resources, user’s guides and hardware support
documents, latest software releases and archived
software
• General Technical Support – Frequently Asked
Questions (FAQs), technical support requests,
online discussion groups, Microchip consultant
program member listing
• Business of Microchip – Product selector and
ordering guides, latest Microchip press releases,
listing of seminars and events, listings of
Microchip sales offices, distributors and factory
representatives
•
•
•
•
•
Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Development Systems Information Line
Customers
should
contact
their
distributor,
representative or field application engineer (FAE) for
support. Local sales offices are also available to help
customers. A listing of sales offices and locations is
included in the back of this document.
Technical support is available through the web site at:
http://microchip.com/support
CUSTOMER CHANGE NOTIFICATION
SERVICE
Microchip’s customer notification service helps keep
customers current on Microchip products. Subscribers
will receive e-mail notification whenever there are
changes, updates, revisions or errata related to a
specified product family or development tool of interest.
To register, access the Microchip web site at
www.microchip.com. Under “Support”, click on
“Customer Change Notification” and follow the
registration instructions.
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 99
MRF49XA
READER RESPONSE
It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip
product. If you wish to provide your comments on organization, clarity, subject matter, and ways in which our
documentation can better serve you, please FAX your comments to the Technical Publications Manager at
(480) 792-4150.
Please list the following information, and use this outline to provide us with your comments about this document.
TO:
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RE:
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Total Pages Sent ________
From: Name
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City / State / ZIP / Country
Telephone: (_______) _________ - _________
FAX: (______) _________ - _________
Application (optional):
Would you like a reply?
Y
N
Device: MRF49XA
Literature Number: DS70590C
Questions:
1. What are the best features of this document?
2. How does this document meet your hardware and software development needs?
3. Do you find the organization of this document easy to follow? If not, why?
4. What additions to the document do you think would enhance the structure and subject?
5. What deletions from the document could be made without affecting the overall usefulness?
6. Is there any incorrect or misleading information (what and where)?
7. How would you improve this document?
DS70590C-page 100
Preliminary
© 2009-2011 Microchip Technology Inc.
MRF49XA
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
X
/XX
XXX
Device
Temperature
Range
Package
Pattern
Example:
a)
b)
Device
MRF49XA: Sub-GHz RF Transceiver
Temperature Range
I
Package
ST = TSSOP (Lead Plastic Thin Shrink Small Outline,
No Lead)
T = Tape and Reel
MRF49XA-I/ST: Industrial temperature,
TSSOP package.
MRF49XAT-I/ST: Industrial temperature,
TSSOP package, tape and reel.
= -40° C to +85° C (Industrial)
© 2009-2011 Microchip Technology Inc.
Preliminary
DS70590C-page 101
Worldwide Sales and Service
AMERICAS
ASIA/PACIFIC
ASIA/PACIFIC
EUROPE
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://www.microchip.com/
support
Web Address:
www.microchip.com
Asia Pacific Office
Suites 3707-14, 37th Floor
Tower 6, The Gateway
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Tel: 852-2401-1200
Fax: 852-2401-3431
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Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
India - Bangalore
Tel: 91-80-3090-4444
Fax: 91-80-3090-4123
India - New Delhi
Tel: 91-11-4160-8631
Fax: 91-11-4160-8632
Austria - Wels
Tel: 43-7242-2244-39
Fax: 43-7242-2244-393
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Noblesville, IN
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Fax: 317-773-5453
Los Angeles
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Tel: 949-462-9523
Fax: 949-462-9608
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Santa Clara, CA
Tel: 408-961-6444
Fax: 408-961-6445
Toronto
Mississauga, Ontario,
Canada
Tel: 905-673-0699
Fax: 905-673-6509
China - Beijing
Tel: 86-10-8569-7000
Fax: 86-10-8528-2104
China - Chengdu
Tel: 86-28-8665-5511
Fax: 86-28-8665-7889
Korea - Seoul
Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
China - Hangzhou
Tel: 86-571-2819-3187
Fax: 86-571-2819-3189
Malaysia - Kuala Lumpur
Tel: 60-3-6201-9857
Fax: 60-3-6201-9859
China - Hong Kong SAR
Tel: 852-2401-1200
Fax: 852-2401-3431
Malaysia - Penang
Tel: 60-4-227-8870
Fax: 60-4-227-4068
China - Nanjing
Tel: 86-25-8473-2460
Fax: 86-25-8473-2470
Philippines - Manila
Tel: 63-2-634-9065
Fax: 63-2-634-9069
China - Qingdao
Tel: 86-532-8502-7355
Fax: 86-532-8502-7205
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
Taiwan - Hsin Chu
Tel: 886-3-5778-366
Fax: 886-3-5770-955
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
Taiwan - Kaohsiung
Tel: 886-7-536-4818
Fax: 886-7-330-9305
China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
Taiwan - Taipei
Tel: 886-2-2500-6610
Fax: 886-2-2508-0102
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
Spain - Madrid
Tel: 34-91-708-08-90
Fax: 34-91-708-08-91
UK - Wokingham
Tel: 44-118-921-5869
Fax: 44-118-921-5820
China - Xian
Tel: 86-29-8833-7252
Fax: 86-29-8833-7256
China - Xiamen
Tel: 86-592-2388138
Fax: 86-592-2388130
China - Zhuhai
Tel: 86-756-3210040
Fax: 86-756-3210049
DS70590C-page 102
Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340
China - Chongqing
Tel: 86-23-8980-9588
Fax: 86-23-8980-9500
08/02/11
Preliminary
© 2009-2011 Microchip Technology Inc.