By Timebeat

Raspberry Pi CM4 multi-constellation GPS / GNSS module

£65.95 - £199.95
Regular price £125.95
Regular price £180.00 Sale price £125.95
Availability: Low stock: 1 left
Regular price £125.95
Regular price £180.00 Sale price £125.95

From the OCP-TAP & Timebeat team comes the best timing and positioning module for the Raspberry PI CM4!

It's made by the same team who contributed the IEEE1588 capability for the BCM54210PE Ethernet controller in the CM4 to the Linux kernel in collaboration with Raspberry Pi and Broadcom.

This module "sandwiches" in between the IO board and CM4 and has expansion slots to extend functionality and performance at a fraction of the cost of a dedicated timing appliance. 

The Timecard Mini is part of the Timecard ecosystem in production with some of the biggest hyper-scalers in the world today.

The module is currently available with three best-in-class modules from world leader Ublox:

  • LEA-M8F <-- you won't get better performance than this anywhere!
  • LEA-M8S
  • MAX-M10S

All are latest generation products and perform better than any alternative in their class. This is Swiss quality and design clock modules, not Chinese copies.

All modules support all GNSS constellations (GPS, Galileo, GLONASS, Beidou, QZSS and SBAS) in either a single of multi constellation configuration. 

The LEA-M8F supports market leading 100ppb holdover and is the flagship product.

All modules contain a built-in TCXO (temperature compensated oscillator), which allows for short-term holdover, maintaining a level of accuracy to UTC in the event the GPS signal is lost.

The Timebeat CM4 Module clicks into the 100-pin connectors of the CM4 which are easily attached to the CM4 IO board. This is a great solution which leaves the 40-pin connector free on the IO board so you can use it for other project specific functionality.

Once an antenna is connected to the module it can be used to provide a PPS (Pulse per second) to the Raspberry Pi device in addition the NMEA and UBX protocol is available without additional cables to allow advanced configuration and positioning services.

Can be combined with free Timebeat or LinuxPTP software to achieve nanosecond accuracy on the device with IEEE1588 Hardware Timestamping (HWTS).

Both LEA options of the module are capable of disciplining an external oscillator for enhanced stability and holdover capabilities. Timebeat has two modules planned for release in the coming weeks which will hold SiTime MEMS digitally controller OCXO for enterprise-grade holdover taking your Raspberry Pi into the big leagues of timing, competing with kits typically sold for several thousand £££.

These expansion modules click straight into place on the GPS module in expansion slots labeled modules A & B.

Lead times may vary depending on stock.

1: ANT: fl IPEX-1 connector for connecting GNSS antenna input.
2: 10 Mhz: fl IPEX-1 connector for connecting stable frequency input to GNSS module
3: PPS OUT: fl IPEX-1 connector for connecting 1PPS output from GNSS module
4: PPS IN : fl IPEX-1 connector for connecting 1PPS input to GNSS module
5: 100 Pin top: Direct connection for the CM4 unit or riser board
6: 100 pin bottom: Direct connection to click straight onto a CM4 IO board or power board
7: Module A & B Hirose connectors: used to connect to Timebeat expansion modules
8: Dip Switch: used to manage the input/output configuration of the PPS Net.

(full guide

The Timepulse pin (Pin 4 on the MAX and Pin 28 on the LEA) can send 1PPS to ETH_SYNC on the CM4 unit provided that the GNSS IN and ETH OUT positions on the dip switch are set to on.

The Dip switch can be found just above the OCP-TAP logo on the right-hand side of the board

The TimeCard mini has a default behaviour of providing a 1PPS to the PPS OUT u.fl connector (connector labelled 3)

Positioning the Dip Switch setting for ‘GNSS In’ to off and switching ‘PPS_IN’ to on, the PPS Net will provide input from the ‘PPS In’ connector (connector labelled 4) and not from the Ublox unit.

The PPS In connector (labelled 4) irrespective of being switched on or off with the Dip Switch the input signal still gets received by the EXTINT pins on the Ublox Unit (Pin 5 on the MAX and pin 27 on the LEA).

In providing the 1PPS to the EXTINT pin you can provide an external stability of measure phase using the EXTINT functionality of the Ublox module. This also means that you can utilise PPS IN and PPS OUT functionality concurrently.

Both modules LEA and MAX connect to serial0 UART interfaces in the CM4.

In addition, the I2C interfaces are routed to the relevant GPIO pins.

The above image details the connections for Module A and B. As the LEA modules allow for a second EXTINT pin we have connected the 10Mhz network of expansion module A and B to the LEA Ublox unit. This allows for the addition of external oscillators.

The LEA-M8F comes with a riser board which adds 2.5mm so allow for clearance, Depending on the case you will need to make sure the height clearance is available when combining with fans or heatsinks, our experience is you can use one of these items at a time (heatsink or fan). The base board looks like the below and comes free with every UBLOX LEA-M8F module.

Time honoured solutions

built around you

  • Tech to suit your project

  • Every unit tested

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  • Free software available