SWRS045F January   2006  – November 2018 CC1021

PRODUCTION DATA.  

  1. 1Device Overview
    1. 1.1 Features
    2. 1.2 Applications
    3. 1.3 Description
    4. 1.4 Functional Block Diagram
  2. 2Revision History
  3. 3Terminal Configuration and Functions
    1. 3.1 Pin Diagram
    2. 3.2 Pin Configuration
  4. 4Specifications
    1. 4.1  Absolute Maximum Ratings
    2. 4.2  ESD Ratings
    3. 4.3  Recommended Operating Conditions
    4. 4.4  RF Transmit
    5. 4.5  RF Receive
    6. 4.6  RSSI / Carrier Sense
    7. 4.7  Intermediate Frequency (IF)
    8. 4.8  Crystal Oscillator
    9. 4.9  Frequency Synthesizer
    10. 4.10 Digital Inputs / Outputs
    11. 4.11 Current Consumption
    12. 4.12 Thermal Resistance Characteristics for VQFNP Package
  5. 5Detailed Description
    1. 5.1  Overview
    2. 5.2  Functional Block Diagram
    3. 5.3  Configuration Overview
      1. 5.3.1 Configuration Software
    4. 5.4  Microcontroller Interface
      1. 5.4.1 Configuration Interface
      2. 5.4.2 Signal Interface
      3. 5.4.3 PLL Lock Signal
    5. 5.5  4-wire Serial Configuration Interface
    6. 5.6  Signal Interface
      1. 5.6.1 Synchronous NRZ Mode
      2. 5.6.2 Transparent Asynchronous UART Mode
      3. 5.6.3 Synchronous Manchester Encoded Mode
        1. 5.6.3.1 Manchester Encoding and Decoding
    7. 5.7  Data Rate Programming
    8. 5.8  Frequency Programming
      1. 5.8.1 Dithering
    9. 5.9  Receiver
      1. 5.9.1  IF Frequency
      2. 5.9.2  Receiver Channel Filter Bandwidth
      3. 5.9.3  Demodulator, Bit Synchronizer and Data Decision
      4. 5.9.4  Receiver Sensitivity versus Data Rate and Frequency Separation
      5. 5.9.5  RSSI
      6. 5.9.6  Image Rejection Calibration
      7. 5.9.7  Blocking and Selectivity
      8. 5.9.8  Linear IF Chain and AGC Settings
      9. 5.9.9  AGC Settling
      10. 5.9.10 Preamble Length and Sync Word
      11. 5.9.11 Carrier Sense
      12. 5.9.12 Automatic Power-Up Sequencing
      13. 5.9.13 Automatic Frequency Control
      14. 5.9.14 Digital FM
    10. 5.10 Transmitter
      1. 5.10.1 FSK Modulation Formats
      2. 5.10.2 Output Power Programming
      3. 5.10.3 TX Data Latency
      4. 5.10.4 Reducing Spurious Emission and Modulation Bandwidth
    11. 5.11 Input and Output Matching and Filtering
    12. 5.12 Frequency Synthesizer
      1. 5.12.1 VCO, Charge Pump, and PLL Loop Filter
      2. 5.12.2 VCO and PLL Self-Calibration
      3. 5.12.3 PLL Turn-on Time versus Loop Filter Bandwidth
      4. 5.12.4 PLL Lock Time versus Loop Filter Bandwidth
    13. 5.13 VCO and LNA Current Control
    14. 5.14 Power Management
    15. 5.15 On-Off Keying (OOK)
    16. 5.16 Crystal Oscillator
    17. 5.17 Built-in Test Pattern Generator
    18. 5.18 Interrupt on Pin DCLK
      1. 5.18.1 Interrupt Upon PLL Lock
      2. 5.18.2 Interrupt Upon Received Signal Carrier Sense
    19. 5.19 PA_EN and LNA_EN Digital Output Pins
      1. 5.19.1 Interfacing an External LNA or PA
      2. 5.19.2 General-Purpose Output Control Pins
      3. 5.19.3 PA_EN and LNA_EN Pin Drive
    20. 5.20 System Considerations and Guidelines
      1. 5.20.1 SRD Regulations
      2. 5.20.2 Narrowband Systems
      3. 5.20.3 Low Cost Systems
      4. 5.20.4 Battery Operated Systems
      5. 5.20.5 High Reliability Systems
      6. 5.20.6 Frequency Hopping Spread Spectrum Systems (FHSS)
    21. 5.21 Antenna Considerations
    22. 5.22 Configuration Registers
      1. 5.22.1 Memory
  6. 6Applications, Implementation, and Layout
    1. 6.1 Application Information
      1. 6.1.1 Typical Application
    2. 6.2 Design Requirements
      1. 6.2.1 Input / Output Matching
      2. 6.2.2 Bias Resistor
      3. 6.2.3 PLL Loop Filter
      4. 6.2.4 Crystal
      5. 6.2.5 Additional Filtering
      6. 6.2.6 Power Supply Decoupling and Filtering
    3. 6.3 PCB Layout Guidelines
  7. 7Device and Documentation Support
    1. 7.1 Device Support
      1. 7.1.1 Device Nomenclature
    2. 7.2 Documentation Support
      1. 7.2.1 Community Resources
    3. 7.3 Trademarks
    4. 7.4 Electrostatic Discharge Caution
    5. 7.5 Export Control Notice
    6. 7.6 Glossary
  8. 8Mechanical Packaging and Orderable Information
    1. 8.1 Packaging Information

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5.9.10 Preamble Length and Sync Word

The rules for choosing a good sync word are as follows:

  1. The sync word should be significantly different from the preamble.
  2. A large number of transitions is good for the bit synchronization or clock recovery. Equal bits reduce the number of transitions. The recommended sync word has at the most 3 equal bits in a row.
  3. Autocorrelation. The sync word should not repeat itself, as this will increase the likelihood for errors.
  4. In general the first bit of sync should be opposite of last bit in preamble, to achieve one more transition.

The recommended sync words for the CC1021 device are 2 bytes (D391), 3 bytes (D391DA) or 4 bytes (D391DA26) and are selected as the best compromise of the above criteria.

Using the register settings provided by the SmartRF™ Studio software, packet error rates (PER) less than 0.5% can be achieved when using 24 bits of preamble and a 16 bit sync word (D391). Using a preamble longer than 24 bits will improve the PER.

When performing the PER measurements described above the packet format consisted of 10 bytes of random data, 2 bytes CRC and 1 dummy byte in addition to the sync word and preamble at the start of each package.

For the test, 1000 packets were sent 10 times. The transmitter was put in power down between each packet. Any bit error in the packet, either in the sync word, in the data or in the CRC caused the packet to be counted as a failed packet.