LooUQ provides several integration circuit boards to facilitate the integration of our modems into your project or product. However you can also directly integrate our modems into your project. 

This guide covers the physical mounting and connections from your host system to each of the LooUQ LTEm modems using both LooUQ integration boards and information necessary to adapt your host to accept you selected LooUQ modem.


The CR-LTEM1 and CR-LTEM2 have the same same physical form, dimensions and signal logic. They also share a common electrical interface with only one minor differences. The LooUQ LTEm UXplor integration boards work with both of these devices. The CR-LTEF3 and CR-LTEK4 are LooUQ modems with different physical forms and interface characteristics.

The LTEm modem boards are 45mm x 40mm. The host interface connector extends out 3mm from the board (16.8mm wide, centered); the host interface header (2 x 8) is designed to mate with a right-angle header (Adam Tech 2PH2R-16-UA, Digikey 2057-2PH2R-16-UA-ND). At the opposite end of the board are two mounting holes designed to accept snap-fit pins (Keystone Electronics 8880, Digikey 36-8880-ND). 

LTEm2 STEP Model

The diagram below shows the dimensions for host boards for electrical and mounting infrastructure. For more detailed information on the modem, including component heights see the linked LTEM2 STEP file (above).


All of the interface signals are 3.3 volt logic level. The LTEm series requires 3.7 volt (nominal) supply voltage; 3.6 - 4.2 volt standard LiPo battery power. The interface pin assignments are found in the table below.


Signal directions are referenced from the modem; In signifies a host signal that controls the modem, Out is a signal from the modem to the host.

Pin (from left)
Signal Name
1VBATPowerPower in, standard 3.7 volt LiPo expected
2GNDPowerSystem ground
3MOSISignal-InSPI data out (from host modem)
4MISOSignal-OutSPI data in (from modem to host)
5~CSSignal-InSPI chip-select (inverted logic, GND=true)
6CLKSignal-InSPI clock
7~IRQSignal-OutCTA IRQ (inverted logic, GND=true)
8TXSignal-InLTEm1: Not used
LTEm2: The AT/Data in, direct to the BGx module
(requires the SPI/HDR jumper be in the HDR position)
9RXSignal-OutLTEm1: The NMEA sentence output
LTEm2: The AT/Data from the BGx module
10PwrKeySignal-InPower on/off (pulse to toggle CTA power state)
11ResetSignal-InResets modem
12~WakeSignal-InInstructs modem to wake
13StatusSignal-OutIndicates that the modem is powered on
14ConnSignal-OutIndicates that the CTA is connected
15EventSignal-OutWhen toggled, signals that the CTA has a new event
16N/ANot Connected

~ prefixed items indicates inverted signal (true when low)