EM7455 for GPS (GNSS) Only

IoT Modules MC/EM Series
1

I will preface this with an apology that I am an absolute rookie when it comes to this stuff.

I have an EM7455 embeded in a Nuvo 5104VTC running Windows 7. I am trying to use it for GPS position only but am having trouble setting that up.

First off, I am having issues even connecting to the modem using a terminal program like PuTTy or Tera Term. Both COM ports don’t seem to work for me - should I be trying to connect through the DM port or the NMEA port?

Secondly, I do not see any sort of GPS information when using SkyLight, it states “Session in progress, acquiring location …”. Does the GPS antenna need to be connected to the GPS antenna port on the card? Or would the MAIN connector work as well?

I am looking for 3D GPS information, that is location and altitude.

Thanks in advance for any information provided.

2

You can connect modem port for AT commamd.
Nmea frame will be output in nmea port.
Please have a look here

3

Thanks for the link above.

I can connect to the COM port but the terminal program (both PuTTy and Tera Term) will not let me type anything. Any suggestions?

4

Are you connecting modem port?

5

I did get connection to the modem and am now able to see GPS data in SkyLight. But when I pass that data along to another program (in my case CANape) it only shows a 2D fix while Skylight shows a 3D fix and displays my elevation. Does this have to do with how it reads the NMEA data?

6

Does it show minimum 4 satellites in nmea frame?

7

Reviving old topic to add the following information “for the record”:

The WWAN modems present several virtual serial ports via their USB interface - that mostly appear as numbered “COM port” devices in Windows. Some of them can be enabled/disabled (making them appear/disappear on the USB bus) using vendor-specific AT commands, possibly also modulo hardwired capabilities of the firmware build (compile-time options). Also note that the WWAN modem modules, to this day, tend to have a physical UART or two - though typically these would be disabled/unreachable e.g. in the M.2 form factor buried in a PC.

Note that in Windows, one of the virtual COM ports gets a special treatment: the one that appears as a “modem device” in the Windows Device Manager. It does not appear in the category of “ports (COM and LPT)”. Instead, it appears in the “Modems” category. Correspondingly, it also gets a different icon. You can also find it by electing to display “devices by connection”, and you drill down through the tree, via ACPI PC, PCI-e root, USB EHCI (XHCI), a few USB HUBs, finally the USB composite device of your expected modem vendor, and then the “WWAN modem” function. It does actually get a numberd COM port name, such as COM5, under the hood. You can find out this COM port number in the “properties” of this modem device, in the Device Manager.
This “modem device” (driver) has some special properties apart from the bare COM port. These extra properties are used by the Windows Remote Access Service / dial-up subsystem. On this COM port, a self-respecting WWAN modem is willing to start PPP, either in CSD mode (data call), or as a shim on top of a PDP context (packet data, for GPRS and later standards). These “RAS related” legacy makes the modem feel compatible with all the Hayes-compatible baggage = think data over PSTN in the eighties and nineties…

Note that modern Windows (since about 7, not sure about Vista) have a different/dedicated driver class for WWAN modems, called the “Mobile Broadband Network” device (see also ‘netsh mbn help’) - this does not depend on the “legacy modem device” (neither the USB device nor its Windows driver), instead it requires a dedicated USB function (to be advertised by the WWAN modem module) and a corresponding vendor-proprietary driver that exports the right “MBN” driver interface class to Windows. I understand that the MBN/WWAN network driver is a subclass/extension of the NDIS network driver interface. This whole modern driver stack is what makes your SIM card’s operator name appear as an entry in the “wireless networks” applet in your systray. (In contrast to legacy modem dial-up connections, managed by the RAS.)

So, typically you can speak AT commands to the WWAN modem using the legacy “modem device”, on its (slightly obscured) virtual COM port.
In addition, many modern WWAN modems have an extra, second, AT Command port. Probably dedicated to “out of band management/monitoring”, while a PDP context may potentially be running on the primary modem COM port.
If you have an “MBN-combatible” WWAN network adapter device and driver also in the system, you may actually be online via this modern driver stack, while both the legacy modem and the dedicated “AT command port” are available for interrogation via Putty et al. (unoccupied).