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.
LTEm
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-LTEM3F and CR-LTEM4K 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).
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.
Power/Signal Interface
The recommended host connector is a Harwin M22-2040805 (DigiKey 952-2323-ND).
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. Pin numbers are referenced from the host connector.
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 | Type | Description |
1 | GND | Power | System ground |
2 | VBAT | Power | Power in, standard 3.7 volt LiPo expected |
3 | MISO | Signal-Out | SPI data in (from modem to host) |
4 | MOSI | Signal-In | SPI data out (from host to modem) |
5 | CLK | Signal-In | SPI clock |
6 | ~CS | Signal-In | SPI chip-select (inverted logic, GND=true) |
7 | TX | Signal-In | LTEm1: Not used |
8 | ~IRQ | Signal-Out | CTA IRQ (inverted logic, GND=true) |
9 | PwrKey | Signal-In | Power state (pulse on/off to toggle LTEm power state) |
10 | RX | Signal-Out | LTEm1: The NMEA sentence output |
11 | ~Wake | Signal-In | Instructs modem to wake |
12 | Reset | Signal-In | Resets modem |
13 | Connected | Signal-Out | Indicates that the LTEm is connected |
14 | Status | Signal-Out | Indicates that the modem is powered on and operating. This signal coincides with the green LED indicator. |
15 | N/A | Not Connected |
|
16 | Event | Signal-Out | When toggled, signals that the LTEm has a new event to be serviced. |
~ prefixed items indicates inverted signal (true when low)