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LPC1114 802.15.4 Wireless Transceiver

An 868MHz/915MHz wireless board based on the Cortex-M0 LPC1114 and AT86RF212 802.15.4 transceiver

LPC1114/AT86RF212 Wireless BoardThis board combines the low-power LPC1114 from NXP (50-MHz, Cortex-M0) with the AT86RF212 802.15.4 wireless transceiver from Atmel (700/800/900MHz).  The longer 868MHz (EU) or 915MHz (US) wavelength provides much better penetration of walls, concrete and other urban obstacles compared to 2.4GHz radios, while still maintaining reasonably high transfer rates (100 or 400 kbit/s, with faster rates possible).

The board has been designed to work off battery power -- ideally a single 3.7V LIPO or Lithium-Ion cell -- and includes a SW-selectable 2.2V and 3.3V output ULDO (though it can be also powered by providing an externally regulated 1.8-3.3V supply on the VIN pin).*  An SMA connector is provided for use with an external antenna (for best range and signal strength), along with a 2-pin JST PH-series connector to allow a secure, polarised battery connector.

*Note: The LM75B temp sensor and SD card require 3.3V for operation. The LPC1114, AT86RF212 an on-board EEPROM, however, can all be run as low as 1.8V.  For more information on minimum voltage, see Standard and Alternate Parts List.

Software: The LPC1114 802.15.4 Wireless Board is generally pin compatible with the LPC1114 Reference Design, and they both use an identical software library, the LPC1114 Code Base.

Key Features

  • Low-power, 50MHz 32-bit ARM Cortex M0 processor
  • 800/900MHz offers excellent signal penetration in an urban environment
  • Complete open source software library and easy to use wireless stack (Chibi from Freaklabs) allows you to get started sending and receiving data quickly.
  • micro-SD connector and FAT32 stack (ChaN's FATFS) to log data to disk, including the option to sniff 802.15.4 traffic directly to SD in libpcap format (understood by Wireshark and other open source analysis tools).
  • Includes a full UART-based CLI to send and receive data wirelessly or configure the device.
  • 4K x 8-bit I2C EEPROM to store sensor node addresses and other persistent values.
  • LM75B temp. sensor for temperature in 0.125°C steps.
  • Polarised JST PH connector to safely attach LIPO or Lithium-Ion battery cells or any other power source.
  • On board voltage divider to measure the battery input (can be disabled in SW to save power).
  • Linear voltage regulator (TPS780) can switch in SW between 3.3V and 2.2V for lower power consumption in sleep mode or when the SD card and temp. sensor are not being used (everything else is 1.8V compatible).
  • I2C, 3 x 10-bit ADC, and high-speed UART-pins broken out, along with reset, VIN/VOUT and a GPIO pin that can be mutiplexed for ADC or PWM output.
  • Can be programmed using ISP and any inexpensive USB-UART adapter or with a SWD HW debugger using the onboard 2x5-pin SWD connector.

Hardware: Schematic

Schematic

LPC1114 / AT86RF212 Schematic

Physical and Electrical Characteristics

  • Board Dimensions (LxW): 58x40mm
  • Temperature Range: -10°C to 70°C (can be modified for -40°C to 70°C
  • Power Input: 3.5-5.5V (DC input, 150mA max) 
  • Power Consumption*:
    • 36MHz Clock, 3.7V LIPO supply, Radio in sleep mode
      • While(1): ~10.6 mA
      • Deep-Sleep (2.2V): ~30 uA
    • 36MHz Clock 3.7V LIPO supply, Radio waiting for incoming messages
      • 3dBm, 868MHz, OQPSK 100kbit/s: ~20.3 mA
    • 36MHz Clock 3.7V LIPO supply, Radio transmitting (2mA LED enabled during transfer)
      • 3dBm, 868MHz, OQPSK 100kbit/s: ~20.5 mA

Disclaimer: These figures are provide for illustrative purposes only, and while they represent our own best efforts no guarantees can be made for power consumption. Overall power consumption is affected by a number of external conditions like temperature and operating environment, and small changes in the firmware can have a significant effect on power consumption in deep sleep mode.
Power Consumption Conditions: 25°C using a 3.7V LIPO cell, SWD debugger disconnected, regulated power supply set to 3.3V. While(1) loop has Systick timer initialised and running at a rate of 1000 ticks per second, UART is initialised for printf support, and two simple 32-bit integers are constantly added together to ensure activity.  SD card and the voltage divider are disabled, and the LM75B is in sleep mode.  Deep-Sleep has the regulated power supply set to 2.2V, with a 32-bit timer running from the WDTOSC at 7.8125kHz to allow SW wakeup, with the following peripherals turned off: IRCOUT, IRC, FLASH, BOD, ADC, SYSPLL, and SYSOSC. All tests were conducted using v0.61 of the LPC1114 Code Base, where a number of optimisations were introduced to improve power consumption on deep sleep.

License

Creative Commons License This work is licensed under a Creative Commons Attribution-Noncommercial 3.0 Unported License. Use of this design should be attributed to: microBuilder.eu.