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rpi-gateways

Raspberry Pi and ic880a based outdoor gateways. Includes build list, deploy scripts and more. This is a staging repo, before public deployment to: github.com/ttn-liv/rpi-gateways

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RPi Gateways

This build is heavily based on ttn_zn's build, but we're extending it to be standardised for several deployments, IP67 rated, with some access hardening, NAT punching and remote logging.

Deployment is controlled via ansible, instructions are in the deployment directory.

TODO: Build instructions are not yet available

Shopping List

Case

For the sensor, case and power supply:

Part Price Order/link
LoRaWAN concentrator board £200 ic880a (IMST Webshop)
UF.L (IPAX) to N-type pigtail lead £7 Solwise PIG-IPAXNCHSSKT25
RPi to iC880a interface £7 supplied from;
Raspberry Pi 2 £32 RPi2:
MicroSD Card (8Gb+) £7 A Sandisk Extreme/Ultra in 8Gb or 16Gb is preferred (based on usage bias) Amazon
up to 32V input down to to 5V output DC-DC voltage converter £11 Pololu 5V 5A Step-Down Voltage Regulator D24V50F5 (hobbytronics)
2.1mm DC socket to micro-B USB plug £1 (Amazon)
IP68 Ethernet DC splitter £5 (Aerial.net)
IP 67 rated enclosure with Ethernet and N-type holes, wall and pole mounting kit £20 (plus £20 p&p) EZNET EZ-SOE01W (Aerial.net)
LMR200/HDF200 co-axial cable £1/meter Solwise HDF200
N-type Plug for LMR200/HDF200 cable (50ohm) ×2 £3.10 Solwise N-Type 200 Plug
N-Type plug/jack inline coaxial surge arrestor £31 Diamond SP-3000P
Ethernet Network surge arrestor £20
  • The IP67 rated case that we're using has N-type connector holes, so we're standardising on N-type connectors for the antenna lead.
  • There are two types of N-type connectors, 75Ω and 50Ω. They are not directly compatible, despite appearing superficially similar. This project uses only 50Ω connectors.
  • This build uses LMR200 or equivalent coaxial cable for the antenna; this is a very similar diameter to RG58. The larger diameter LMR400 would also be suitable (and would require alternative N-type connectors), this would provide a much lower resistance (0.1Ω/m vs 0.3Ω/m) and longer range.
  • Regardless of the cable diameter, is recommended that the the coaxial length is kept to the minimum, ideally less than 1.5m.

Board Mounting

For the Raspberry Pi, interface board and concentrator board:

Part Qty Link
M2.5×8 nylon set screw 6 Farnell 2472704
M2.5 nylon nut 6 Farnell 2472686
Brass spacer 4.5×3mm 4 Farnell 1466898
Brass Jack screw (male-female standoff) M2.5×11 4 Farnell 2494583

For the Pololu DC-DC converter:

Part Qty Link
M2x5 nylon set screw 4 Farnell 2528936
M2×10 standoff (female-female) 2 Farnell 2494574

Power Supply

To reduce the cabling and case openings in the IP67 case, the raspberry pi is supplied with power using Power over Ethernet (PoE). The chosen Pololu DC-DC converter can step down voltages up to 32V, but PoE supplied at 12V or 24V will be sufficient.

Part Cost Link
A 12V supply with a 2.1mm DC plug OR a proper POE injector
Cat5E or Cat6 Ethernet cable (for external use)
8P8C (aka RJ45) connectors

Antenna option 1

Quarter wave ground plane:

Part Price link
¼ wave ground plane omnidirectional antenna £45 Aurel GP868 (Conrad Electronic)
BNC jack to N-type plug adaptor £5 TE Connectivity 1-1337567-0 (Farnell)
  • This antenna is has an F-type jack and is supplied with 2.5m RG58 cable which is terminated in a BNC plug. The BNC jack to N-type plug adaptor allows connection to the N-type pigtail in the case.

Antenna option 2

Half wave dipole:

Part Price link
Barracuda 5dbi omnidirectional antenna £90 Digikey 931-1255-ND Taoglas OMB.8912.05F21

Tools:

Part Price Order link
N-type coax connector crimping tool for LMR200/RG58 £24
RG58/LMR200/HDF200 coaxial stripping tool £12 332D Stripping tool (Solwise)

Testing

The following parts are not required for the build, but might be useful for on-the-bench testing. No more than one of each is needed:

Part Price Order/link
UF.L to SMA pigtail lead for test antenna EUR 6.5 (excl. tax) IMST Webshop
SMA ¼ wavelength Test Antenna £5–£10
RPi Power Supply 2A with micro USB £9 Farnell