Farm Jenny LTE-Thread Border Router HAT
If your ready to jump right in, follow the Quick Start Guide for the Farm Jenny LTE Border Router HAT.
Turn a Raspberry Pi or compatible Single Board Computer with 40-pin header into a feature-packed cellular Border Router. Just add your favorite pre-certified cellular modem.
A Border Router connects a local wireless network to other IP-based networks. This board was designed to implement a Thread Border Router, but its Nordic Semiconductors nRF52840-based radio module can support a variety of wireless protocols, including (Thread, BLE, Zigbee, and proprietary).
Features
- Socket for a wide variety of Nimbelink(R) or compatible end-certified cellular modems (not included)
- Certified nRF52840-based BLE/Zigbee radio with PA/LNA for long range
- Radio programming via standard Tag-Connect socket
- NFC Tag interface (flex/antenna required)
- Four (4) status LEDs (Power, Cell, BLE/802.15.4, User)
- One (1) momentary pushbutton
- Connector for LEDs/Button on external overlay
- USB interface for full cell modem access
- Pass-thru 40-pin connector for stacking
Pinout
This board conforms to the electrical specifications at https://github.com/raspberrypi/hats. The board does not back-feed power on the 5V pins. You must provide an adequate power supply for the Pi that can handle the current required by Pi and cell modem. Unless otherwise specified, all I/O uses 3.3V logic levels.
Where practical, the board has been carefully designed to play nicely when stacked with other HATs. Non-essential I/O has been connected using cuttable jumpers on the back side of the board, in case it conflicts with another HAT used in your system. See below for jumper locations.
Mechanical
This board conforms to the mechanical specifications for a Raspberry Pi HAT, refer to: https://github.com/raspberrypi/hats/blob/master/hat-board-mechanical.pdf
Power:
IMPORTANT You must provide an adequate power supply for the Pi that can handle the current required by Pi and cell modem. This HAT takes power from the Pi's 5VDC supply pins and uses a very robust 3A power supply to generate the 4V required by the cellular modem. OUr power supply includes generous bulk capacitance to filter out large spikes in current demanded by the modem, however depending on the modem model, peak and sustained current demand can still be very high. Even so-called low-power cellular technologies like CAT-M1 and NB-IOT can require short bursts of high current.
The HAT draws less than 50mA from the 3.3V power supply of the Pi.
2.4GHZ Radio Module
The board includes a Fanstel BT840XE radio with full modular certification. This module includes a Power Amplifier (PA) and Low-Noise recieve Amplifier (LNA) for long range and can use a variety of internal and external antennas connected using the u.FL port. The radio module includes a 32.768kHz crystal for accurate timing or low power sleep modes.
The Radio interfaces with the Pi using a high-speed SPI port, including an optional interrupt line.
By default, the Radio comes programmed with OpenThread Network Co-Processor (NCP) firmware and no bootloader. Custom programming is available on request. Firmware can also be programmed using a compatible SWD programmer/debugger and 6-pin Tag-Connect cable.
USB Port:
The board includes a micro-USB port (J2) connected to the cellular modem. This connection is for data only. The board CANNOT be powered through this USB connection and is intended for use only when installed on a suitable Single-Board Computer.
Serial Port:
Connector J1 provides an easy connection point for a serial adapter for development. Signals are 3.3V logic level and are ESD-protected, but not isolated or buffered. Use of a UART-to-USB adapter, such as TTL-232RG-VSW3V3-WE or TTL-232RG-VIP-WE from FTDI is recommended. If you wish to extend this interface outside the end device enclosure, additional protection circuitry or drivers may be necessary. By reconfiguring the jumpers, the Raspberry Pi's serial port can also be connected to the cellular modem (see pinout for more details). In most cases, this is not necessary as the cellular modem will enumerate multiple virtual serial ports (e.g., data, AT commands, etc.) over the single USB interface.
User Interface
The HAT includes 4 LEDs and one pushbutton. The same signals are available on a 6-position 1mm CIC flex circuit connector, suitable for connection of an overlay. When the overlay is used, it is helpful to depopulate the onboard LEDs. Contact us if you are interested in production quantities with these components removed.
NFC Tag Interface
The NFC connector is compatible with the NFC antenna shipped with Nordic Semicondutors Development Kits (DK), or a similar antenna available from Laird. Custom antennas may be designed or incorporated into an overlay.