PPS Piggy

The “PPS Piggy” is a companion board to the Trimble Resolution SMT carrier board and Resolution T that makes it easy to connect to a PC via either RS-232 or USB.

It provides a linear 3.3V power supply for the RT/RSMT board and 3.3V or 5V for the antenna, all from a 5V input (either external or from USB). Serial communications is available via either USB or RS-232 or both. If both are connected, USB takes precedence and can transmit to the RT or RSMT board, but both RS-232 and USB always receive data simultaneously from the RT or RSMT. Pulse-per-second output is provided via the RS-232’s DCD (carrier detect) line, and a 50-ohm driven 100mil header connector. An unpopulated SMA footprint with the same 50 ohm output is also provided. The 50-ohm output will drive 2.5V into a 50 ohm load, or 5V into a high-impedance load.

front view of pps piggy

The PPS Piggy is no longer being sold, but design files are available below.


  • 5V input power via header or USB
  • Onboard 3.3V linear regulator
  • Solder jumper for selecting 3.3V or 5V for antenna power (default 5V)
  • Serial RS232 on DE-9 female connector
  • Serial USB on 5-pin Mini-B connector
  • Pulse-per-second on the RS232 DCD pin (negative-going)
  • Pulse-per-second on 100mil header (positive-going) and unpopulated SMA connector, drives 2.5V into a 50 ohm load or 5V into a high-impedance load
  • 4-pin header with logic-level (3.3V) serial and PPS - use with Arduino, Raspberry Pi, or other microcontrollers alongside your PC
  • Board has same shape and mounting holes as RT/RSMT board, and mounts directly on top
  • Windows and Mac OS drivers for USB connectivity are available from FTDI. No drivers required for operation under Linux.
  • Revision 4 and earlier: Windows drivers available from Microchip.


PPS Piggy is open-source hardware, provided under the Creative Commons Attribution 3.0 license It was developed with Altium Designer but a PDF of the schematic as well as the Gerber and NC Drill outputs is provided below. The current revision is number 5.3.

angle view of pps piggy