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Software-related FAQ
Hardware-related FAQ

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Q - I want to set a recurring time alarm by the hour and not have to set the date. e.g. the example specifies a date each time. I just want it to wake up at say 4:00pm each day without having to reset the date and time. Do you know of a command?

A - The AT command is AT+CALA and it is possible to set a recurrent alarm for all the days of the week with the format:



AT+CALA="08/11/13,12:30:00+00",0,2,"ALARM",0,0 where <recurr> = 0 (all the days)

To set the clock the command is AT+CCLK.


Battery & Power

Q - How does AT+CBC affect the battery charger?   

A - AT+CBC monitors the battery level. See AT command manual 2.6.8

Q - What does AT#VAUX do – is it an ON/OFF control? 

A - It can be switched ON/OFF by AT command AT#VAUX.

Q - I noticed that there is a fault condition depending on how the power is applied to the module.

Referring to page 312 of the AT Command set - here it describes a condition within the charger AT+CBC command which returns a fault condition <bcs>=3 which places the modem in "calls inhibited" mode. Can you advise back the recovery procedure, is that a soft reset?

When would the user be able to receive the <bcs>=3 response (recognised power fault, calls inhibited)?

Note: without battery/power connected on VBATT pins or during a power fault the unit is not working, therefore values <bcs>=2 and <bcs>=3 will never appear.

A - The best solution would be to disconnect the CHARGE power, power off the module using the RESET pin (in this condition it is possible that ON/OFF doesn't work) and then power on the module again connecting the CHARGE input.


Q - How you can transfer data say a JPEG image into the same RAM memory location as for AT#TPHOTO command either with the IIC or SPI port thru the use of Python script command in one of the Python modules? Can you advise how much RAM space is set aside also or does this vary depending on how you set up the photo resolution and compression?

It’s funny because I notice that there are two AT commands #RPHOTO and AT#OBJR available for flushing the photo RAM to the serial port but no commands available to read data from the serial port back into photo RAM!

A - You cannot access the RAM memory location but you can store data coming from SPI or IIC bus into the NVM Flash memory using:

data = '' "

file = open('data.txt','wb')
data = MDM.receive(50)

Therefore only the AT#TPHOTO command is enabled to write into the RAM the photo taken from the CMOS camera.

Q - Does AT#CAMON/OFF affect VAUX1 (or is it GPIO8)? 

A - The CAM_ON pulse is provided by GPIO8 pin6.


Q - Does Telit have AT Commands available for selecting compression settings like Half Rate, Full Rate, Enhanced Full Rate, etc.?

A - The command is AT#CODEC.


Q - I am having difficulty getting CMUX to work properly on my modem.

A - Telit Serial Port Mux.exe  application needs the following signals: RX,TX,RTS,CTS,DTR,DSR (and GND) please check this first!

Q - I am having difficulty getting CMUX to work properly with the GR1 or GE863-GPS.

A - There is a new function which has been added into the CMUX function refer to page 71 of the AT Command r4 document attached, I have pasted the change below. In order to circumvent this problem it is required now to assert AT#CMUXSCR=1 this will override the 5 seconds allowing CMUX to be enabled at power up, refer to page 399 of the AT Command r4 document.

Q - We still have some old V3 GM862-QUAD-PY modems and I would need to know if these are flashed to the highest revision of the V3 firmware what AT commands they will support. My main issue is with the new GPRS socket commands and with the Python AT#STARTMODESCR and if there are any other commands which the V3 firmware/hardware does not support? Is there a document you can send me?

A - It is quite simple. V3 modules supports all the AT commands classified on #SELINT=0 and #SELINT=1. All the new AT commands implemented only on #SELINT=2 are not available.
Have a look at backward compatibility table, page 24.

80000ST10025a_AT_Commands_Reference_Guide_r0.pdf 2.04MB


Q - Can you clarify the performance of the GSM voice channel for custom DTMF signalling?

A - If I've understood well how the application works, the DTMF tone is sent through the voice channel from the microphone of the module and received on the speaker of the second module/phone like a voice signal. This could cause problems because the GSM vocoder cannot manage single or double tones (the voice is modulated) and sometime it can start modulating its amplitude with a variation from 0% to 100% depending on the frequency. 

This is not a specific problem of Telit or other manufacturers’ modules but it is related to the GSM technology. Only constructed tones like the one generated by AT+VTS can be received without any problem because the tone is not sent on the voice channel as an analogue signal but as a digital one and regenerated by the DSP receiver.


Q - I am having trouble issuing commands related to the custom commands for Enhanced Easy GPRS commands only?

A - First try issuing AT#SELINT=2 if this doesn’t fix the problem then try inserting a SIM card as some products require the SIM be inserted first.


Q – I am having difficulty updating the new 7.03.x00 to my GC/GE series module?

A - The latest 7.03.x00 cannot fit into old QUAD modules (4MB flash) since integrating FOTA it needs 8MB flash modules.

The latest production firmware for these modules is the 7.02.x04 already integrating the multisocket commands.

HTTP & Web Server

Q - I wish to write a small web host for the GE863-GPS, do you know if there are any tools available to simplify the creation of a web page for our Python platform? Is there any information available you can send me?

A - I know that some HTTP code should be already available in the net. You can find some information on the following links:


Q - Is the MDM.Read command buffered? How can the customer implement an interrupt to a com port without loosing data?

A - The MDM.receive() .read() and .send() buffer is 2048 bytes.

MMS Messages

Q - The scenario is as follows. It is evident that the Telit module has a well advanced GPRS component. However there is little or no write up on sending MMS messages. Specifically to this task, I need to send an image captured by a still camera which is controlled by the Telit module to a second mobile phone, with only the prior knowledge of the recipient's mobile phone number. When using GPRS, one must know the server's IP address. I also understand that the recipient will have to have gprs enabled on their phone, and consequently their phone has an IP address, however we are hoping to do this without the client having to find out his/her IP address from their service provider. Surely this is possible.

A - Our modules cannot send MMS directly to another phone because WAP is not supported.

Basically, MMS is implemented using a combination of WAP and SMS technologies.

The process of delivering an MMS message to a handset works like this:

1.) It starts with a content file that contains the content of an MMS message. This message may have been created by an application, or it may have been created by a user sending the message from a mobile phone. (When the message is sent from a mobile phone, a mobile phone connects to an MMSC via WAP and transmits the MMS message content to an MMSC and the MMSC then takes responsibility for further delivery.)

2.) The MMS message content is published (usually by an MMSC) so that it is accessible via a URL.

3.) An MMS notification message is sent to the recipient mobile phone, encapsulated in a WAP push message, which itself is encoded as a binary SMS (the WAP protocols define an encoding for WAP push over GSM SMS). This MMS notification message contains header information about the MMS message, and a URL pointer that tells the mobile phone how to retrieve the MMS message content.

4.) The recipient mobile phone opens a WAP session, and retrieves the MMS message content from the URL contained in the MMS notification message.

That's pretty simplified, but that's a good brief overview. In most of the cases above, the WAP sessions are TCP/IP over GPRS (although this is not a requirement).

There are different web site talking about MMS and WAP. One of these is

Another solution is to send image as email attachement and use an email to MMS gateway, such as nowsms.


Q - It appears when SMS message is received that the GM862 modem can become disconnected from the network?

A - It is the standard behavior of the module. After receiving or sending an SMS the module starts a re-registration (It change the control channel). This takes no more than 5 seconds. After this time the AT+CREG? returns again +CREG: 0,1

Q - With our application idling for about an hour, I just got another instance where the GM862 responded to "AT+CREG?" with "+CREG: 0 2" i.e. not registered. I don't know why this is happening but, since we are checking network registration status at one minute intervals, I was wondering if I should look for two successive not registered status returns before deciding that the GM862 had actually lost contact with the network.

A - I would like to suggest this procedure.

  1. The microcontroller check the GSM registration status
  2. If the +CREG response is different from +CREG:0,1 or +CREG:0,5 it starts checking the network every 10s
  3. If after 1 minute (6th check) the +CREG still return a value like (2, 3 or 4) the microcontroller can force a manual registration (+COPS)

Q - We are doing a project with Vodafone NZ and I need to get the Cell ID name.  For example when I'm in Newton, Auckland my phone displays the name of the site to be Newton. I have been using AT#MONI=0 and then AT#MONI to get the cell ID but if gives a hexadecimal number that doesn’t relate to the actual work “Newton”.

A - What you are looking for is the broadcast information of the district.

This is the procedure to enable cell broadcast:

After a while I receive
+CBM: 32,50,0,1,1
+CBM: 32800,50,0,1,1

+CBM are unsolicited messages sent by the network. It is not possible to query this information with a AT+XXX? command.


Q - Is it possible to pre-compile the Python script before loading it onto the module? For example would it be possible to compile the script on the module copy it and download to another module?

A - It is possible to compile a py script inside an module, then download the pyo file created and upload it into another module with the same software version.
       It is possible to use the attached tool to download the whole FDI memory (user parameter location) and upload it into another module.
       Type V3: GM862/GE863QUAD & QUAD-PY
       Type Lite: GM862/GE863GPS & GE/GC864

Q - I have noticed a limit to the script file that can be sent using "AT#WSCRIPT". I have found it to be approx 7,000 bytes. To upload scripts larger than this I have to do it through Python, using file commands. This isn't a problem, more a point of interest. Also there appears to be a limit to the script size that Python can compile. I think it is approx 13,000 bytes. I am still trying to get around this one. My question is, is there a way I can pre-compile a script on a PC? I could then upload the file using Python's file commands.

A - Actually the script upload is not limited. The the max size of a single script on the latest software is 2^32 = 4GB. The previous limit was 64KB.
The script upload must be performed at 115200, 8N1, with hardware flow control active.

There is a limit of 682 elements (variables, functions, strings, constants...) that can be used in a script. These elements are stored inside a dictionary during the parsing phase; if the number of elements used overcome the 682 units, the script returns a memory error message. To avoid this problem we suggest to call with the same name, different variables, strings, etc. where it is possible.

You can precompile your scripts inside a module, then download it with the AT#RSCRIPT="file.pyo" command and upload the pyo file to another module. The important thing you have to consider it that the modules must have the same software version.

To simplify this procedure, the Python Boot Manager softwarwe tool may be used. With the Python Boot Manager it is possible to download/upload all the scripts inside a module to another one.

The Python Boot Manager is available for download on GLYN's password-protected website. Please request username & password at

Q - Is it possible to implement the script "know how" hidden command on an ftp file?

A - yes it should be possible.

First they have to download the file from FTP server (#FTPGET..) and store it into a file object or into a variable (16K max.).

Then use the AT#WSCRIPT and after the prompt >>> download the file with MDM.send.


Q - I am running a Python script using the GM862-QUAD-PY on an EVK3. What I noticed is that while in command mode when I type the AT#REBOOT command, I can see that the modem reboots but script no longer runs?

A - AT#REBOOT should be used inside a script to reboot the units in particular cases (i.e. reboot the unit after an OTA upgrade of the script).
If you use it in command mode you should be very fast to disconnect the serial port. It was not thought for this use...

Q - It appears that the hardware reset is intended to shut down the GM862-GPS module is that correct?

A - Yes, the latest product description describe the new behavior of the RESET pin. This is valid for the GPS products only.

Q - My feeling is that this means that the customer can keep the ON/OFF pin tied to ground so that if ever the perform hardware reset then the module will automaticaly power on, is that the correct interpretation?

A - It is possible to keep the ON/OFF pin low and perform a reset. In this case the module will be "rebooted".

Q - If soft reboot command is issued, does the module detach properly from the network?

A - Only the ON/OFF pin and AT#SHDN perform a network detach. In fact the RESET pin must be used only as an emergency escape.

Q - Is there an AT command for a software re-attachment to the network, is it possible for example to monitor the GSM connection and if no connection to assert an AT command for re-attachment?

A - It is possible to force a network registration using the AT+COPS command (AT+COPS=1,2,"net_code") or search for available AT+networks with AT+COPS=?

Secure SSL

Q - I have a customer wishing to know if our modules provide a secure socket layer over GPRS and how to enable?

A - We do not support SSL. This protocol is too heavy to be implemented on LITE chipset. By far the most "expensive" operation in any SSL session is the public-key operation.    
... the initial handshake time can easily be ... 30 seconds ... on a 44MHz processor. Its implementation will be considered again on next chipset family.

SIM Card

Q - Please note that the SIM card in this instance is unlocked and the PIN and PUK are not being used, so far. The AT sequence AT+GCI reports country code 59 for Italy as the country of ‘installation’ per the ITU T.35 Annex A country listings. This code is not amendable, and remains set at 59. Australia’s code is 09, and the other countries in which we might install are also varied. Is there any requirement for this code to ever change according to the country of USE, or can it remain Italy(59) without any prejudice?

A - It doesn't matter how you set AT+GCI. This command is only supported to be compliant with old PSTN modems but it isn't used.

Q - The AT sequence AT+CNUM reports +CNUM: “0”,129 for all manner of SIM card from several different TELCOs. I thought it might report the phone number on the SIM card. Is there something I am not doing correctly?

A - AT+CNUM returns the SIM card numbers if the number has been previously stored by the network operator or by the user. There are no existing commands to write the number therefore you should do the operation using a cell phone that implements this feature...


Q - Is it possible to enable the SSC within the Python SPI built-in module, for example would it be possible to multiplex serial communication on a single SPI port?

A - Do you mean the SSC used for Python debug? This is set internally in the uP code. You can create more than one SPI port but you cannot multiplex the same SPI with more than one device.


Q - Is it possible to have multiple TCP/IP sockets open simultaneously?

A - Not yet. We are deleveloping the multisocket feature (up to 6 sockets) but it won't be ready before Winter 2006.

Q - We are currently testing out the Telit's ability to send udp packets and have some questions. We are currently able to send packets out and they reach the destination no problems. However, when sending a packet back to the telit from our server, nothing comes through. This is strange becuase the telit can successfully do a dns query which uses udp. I have even tried to connect to dns servers using at#sktd, and tried manually to perform a query with no success.

A - I heard about this problem a lot of times....are you using the hardware flow control (RTS/CTS) ? Are these lines set to 0V? If not used or unconnected they have to disable the HWF with AT&K0.

Q - Do you know what is the maximum length of data I can send using the Telit TCP/IP stack?

A - 1500 bytes on one sigle packet (AT#PKTSZ or AT#SCFG).


Q - There has been some suggestion of being able to find out, from the GSM network, something of where we are in terms of timezone. There is a command in the AT set to ask what TIMEZONE the unit is currently in. I wonder if that is true. The command is AT#NITZ.

However, there are fields in the time setting command AT+CCLK that require a timezone setting from -11 to +11, and it bothers me that that is the only ‘meaning’ of timezone in the GE863 context. If the timezone is only what you set it to, I would like confirmation that that is all there is to it, and it has nothing to do with the outside world. That is, there is nothing clever about it whatsoever – it is just what the user sets it to.

And how do we deal with timezones, as in Australia, where they are resolved to 30 minutes? Seems to be a little problem there.

This is related to the previous question about the relationship between the AT+CCLK settings and any time that comes from the GPS, that should naturally be in UTC time with no local timezone other than Greenwich ZULU. Timezone is difficult to resolve (it is very hard indeed) as it depends on your latitude AND longitude, so that is no simple lookup table. It is a very difficult lookup table.

A - The AT#NITZ command enables the automatic date and time updating. Date and time are sent by the network (not all the networks) after a GSM registration or GPRS attach. This string contains date and time info but not the TIMEZONE (+1, +2, +3...).

As our documentation says about AT+CCLK, the module doesn't support timezone information therefore it is possible to set this parameter (expressed in quarter of an hour, between the local time and GMT; range -48--+48) but the three last characters are not returned.


Q – What are the UC864 AT Commands required to connect to the high speed HSDPA channel?

A – The UC864 module is configured by default to get registered to UMTS network therefore the AT command you have to use to set up a HSDPA connection are the same of a GPRS module. 

New commands or parameters are:
AT+WS46=25   use both UTRAN and GERAN network (default)
AT+COPS=x,"NW_name",<AcT> where Act can be 0 -GSM or 2 - UTRAN



Q -
How many ADC channels exist on the GPS version and how do you access them ? AT#ADC, AT# … 

A - One ADC (pin23) and one DAC (pin63) channels are available.

Q - How can one control the DAC PWM operation? 

A -


Q - I am concerned about the GE863-GPS antenna voltage feed for an external powered antenna. My antenna supplier suggests a maximum of 3.3 Volts for the antenna at 15 mA drain current ( with inbuilt LNA). Is the LNA power source of the GE863-GPS is capable of being controlled to less than 3.3V (perhaps by nominating a limiting feed current with command AT$GPSAP=1,015) or I should isolate the antenna feed and add my own DC injector as a separate feature.

A - The supply voltage of the GPS antenna is referred to VBATT. This means that a typical value is 3,8V. I think that the antenna supplier could suggest an antenna that fulfill the module's requirements. Otherwise an external regulator is needed.


Q -  Is it possible to swap the Li-Ion battery with Li-Polymer? Does the Li-Ion charger also charge Li-Polymer? I have been using a Li-Polymer battery 3.7V 1600mAh with the Trizium-GPS module and does not encounter any problems.

A - No problem. The E-Power chip can work with Li-Ion and Li-polymer batteries; the levels are the same.

Q -  What function is performed by the pin labeled PWRMON?

A - PWRMON can be used to monitor the module's status (ON/OFF). High = ON; Low = OFF


Q - Do you have any pricing for cameras that can be attached to these units along with specs?

A - There is no longer any camera support as we continue to have to deal with camera obsolescence issues we have tripped this function out of our firmware.


Q - I notice that there is a Darlington Transistor array ULN2003 buffering the GPIO port pins. My customer wishes to increase the available inputs so will need to bypass the ULN2003 to set up the GPIO2,5,6 and 7. R94 to R99 are these used to by-pass the ULN2003A?

A - U6 ULN2003 is used to drive 4 open collectors 2 LEDs and 1 Relay. You can only use R94, R95, R96, R97 this will give you 4 more inputs on the 24pin connector. R98 use for override the ULN2003 but this will go only to the relay and the same for R99 to the GSM led.

Q - Is the jumper JP1 used to force the module to turn on automatically?

A - JP1 use to keep the GE864 on all time -- recommended to be on,  
scenario -- in EZ863 GPS the battery can go down to 3v after few hours of use, when power up on the input the modem will not start automatically, only with the ON/OFF front switch push bottom.


Q - The Product Description guide includes the pin allocations for the GC864 however I can not find any IO data for the GC864-PY. Do you have a document available with the I/O for the GC864-PY?

A - Telit GPIO are available from pin 56 to pin 78.

Q - Are interrupts available on the I/O port pins, for example how does a customer interrupt a com port if there is activity on another I/O port pin?

A - Interrupts are not available but may be you mean how to handle the hardware flow control to stop serial port sending/receiving.
       MDM.getCTS() and MDM.setRTS() can be used for this purpose:
       The flow control works this way:
        when the user needs to stop the incoming data from the GM862 MDM.receive() module (remote host => GM862) 
        it set the MDM.setRTS(1) signal and the module will stop sending data as long as the RTS is 1.

        On the opposite direction, when the GM862 needs the script to stop sending data (MDM.send()),
        it RAISES its CTS (MDM.getCTS() returns 1) and the script must stop sending data to the GM862 as long as the CTS is HIGH.

Q - Can you please tell me the state of the GPIO pins on initialization. i.e. before the Python scripts starts. I assume they are logic 0 outputs but I would like to confirm this.

A - Almost all the IO port pins have internal pull ups so will always look like they are set..!

GPIO2 is Open Collector so requires a pull up to be configured as Output.

GPIO1 reading the status of this pin will be the reverse of the actuall logic state as there is a coupling transistor inverting the read value.

You can refer to page 151 for reading the status of the input pins.

AT#GPIO=4,2 {Read GPIO port pin 4}
#GPIO: 0,1 {Pin 4 is reported as INPUT, status is SET}

Jammed Detect & Report

Q - What function is served by JDR on GPIO2?

A - The Jammed Detect & Report feature allows a Telit GE863 module to detect the presence of a disturbing device such as a Communication Jammer and give indication to the user and/or send a report of that to the network. Have a look at the Product description 5.2.

Real Time Clock

Q -  There is a pin called VRTC that calls for a backup capacitor. However, during power outages or deliberate shutdown of VBATT, the RTC may fail to operate and I would like to know how to keep it running. There is an Application Note about RTC backup for the earlier TRIZIUM series that suggests a 2.0V backup supply derived from an LDO and a 3V Lithium backup battery. Is that the right approach for the GE863-GPS? 

A - I would like to suggest to use this application note for the GPS modules.
Primary Battery for RTC Application Note.pdf   40 KB

Q - Does PPS present a 1-pulse per second signal ? What is the pulse width? 

A - It provides 1 pulse per second. The width is 1uS.

Q - Is the internal GSM clock separate from the GPS clock as reported in GPS NMEA strings? 

A - Yes it is separate. The RTC is not affected by the GPS clock.


Q - RESET pin behaviour.  Does this have ONE or TWO functions depending on the length of the pulse?  The Hardware Users Guide talks of an “Unconditional shutdown” to be used if the unit locks up that can be achieved by a pulse longer than 200ms.  However a different section says the device resets on a falling edge.  Does this falling edge “nicely” reset the device (and try to deregister from the network cleanly), so that short (<200ms) pulses can be used to “soft reset” the device, whereby >200ms pulses unconditionally shutdown the device on the rising edge? 

A - RESET input operate in a unique modality, by a pulse longer than 200 ms. When it is written “on a falling edge” remains understood that then it must remain low for at least 200 ms.

PCB Layout

Q - Do you have any layout software for the GE863 series footprint?

A - Please find attached the PDF and DXF files for the GE863GPS. DXF file is the best we can offer as mechanical drawing.

3990400495.pdf   122 KB
3990400495.dxf 841 KB

Q - Can you also provide information regarding the usage of the gold plated test pads on the GE863 package?

A - The gold plated test pads are used by our test equipments during the production. Customers don't have to solder the test pads on their applications. \


Q - When I tests the CTS pin it appears to always be asserted however this does not agree with the data sheet.

A - Please note that all the commands (AT&D, AT&S, AT&C, AT&K) refers to the RS232 behavior. RS232 behavior is inverted compared to the CMOS level of the module. The CTS pin of the module is always off (0V) and goes ON (2.8V) when the serial buffer is filled and the module wants to stop the data flow from the micro/PC. RTS/CTS works only in online mode (data connection active).

Q – Is it possible to use the UART to send and receive high speed data instead of the USB port?

A – Yes it is possible to use the UART port to send/receive data the max baudrate is limited to 230400bps.

Q - RX_TRACE and TX_TRACE.  I can’t find any documentation about using this other serial port other than in the Hardware Users Guide which says use them as a second serial port for debug.  Is this a full function serial port with AT access like the primary serial port, or restricted to certain operations?  What serial parameters would I use to talk to it, and can they be changed?  Can the module firmware be updated through this port as well, or do I need to implement tristate or passthrough with the micro to allow firmware update through the primary port as described in the note in section 8.2?

A - RX_TRACE and TX_TRACE are dedicated to a Run Time Debug Telit Tool, used from R&D to investigate about various issue. From this GPIO isn’t possible operate a firmware update or put the AT command. Moreover Telit don’t furnish the related communications protocol.


Q - Does the designer need to connect pin 35 if standard USB type A (host) but also type B (device) connectors is foreseen in the design?

A - At the moment, UC864-E supports only Slave mode (USB type B) with pin 35(USB_ID) open (Not connect). USB-OTG is reserved for the future.

Q - If the designer does want to design-in a USB micro type A or B, maybe also a micro-AB, pin 35 as a consequence need to be connected then? Is this true? What about the mini B?

A - For the USB-OTG feature, pin35(USB_ID) has to be connected. USB_OTG device have to sense the voltage level on the pin 35, then it determine itself to function as the master device, or the slave device. When it senses less than 0.15Vtrm(Vtrm=3.3V typ.) it functions as the master device, or when it senses more than 0.8Vtrm (Vtrm=3.3V typ.) it functions as the slave device. In the UC864-E, there is the pull-up resistor on USB_ID pin to Vtrm. Consequently if pin 35(USB_ID) is open(Not connect), it senses more than 0.8Vterm , then UC864-E works as a USB slave device. If pin 35(USB_ID) connected to ground, then UC864-E works as the USB master device.

Q - What about the correct pull-up and pull-down resistors, respectively in order to get most beneficial data exchange of host and device in upstream but also downstream in all cases above?

A - If you are talking about USB_D+, USB_D-, I don’t think they need resistor since already our USB solution may have it. If you are talking about USB_ID, refer to the answer above.

Q - Is your device also capable of negotiation the protocol for USB OTG (ON THE GO) support (USB micro-AB)?

A - Currently, it does not support full USB-OTG features, but slave functions only. Master function is reserved for future use.

Q - If you forget to cut USB_VBUS while device is shutting down is there a risk to damage the device as such?

A - No damage. But Before you try to shut down the module, you have to cut off USB_VBUS first. Otherwise you can’t shut down the module. It powers on again automatically.

Q - If USB_VBUS has been already connected while device is starting up is there a risk to get the module damaged? Is this the reason why you have to monitor the POWERMON signal continuously?

A - When VBATT power supply, if USB_VBUS power supplied, the module powers on without ON_OFF button pressed regardless of your intention.

Q - Can the interface still work with 4V USB_VBUS instead of 5V as specified according to USB standard?

A - We do not guarantee 4V USB_VBUS. You should supply 4.5V min. - 5.25V max. for USB_VBUS.

Q - If you have USB_VBUS in use what minimum drive current (USB_VBUS signal) is then needed to drive the interface whenever module is supplied by VBATT? The starting up scenario is the same as proposed in the appropriate note of the HW manual (page 12 first note).

A - USB_VBUS drive current is not more than 25mA max. When you supply USB_VBUS power with VBATT power supplied, UC864-E turns on itself
automatically without ON_OFF button pressed. So if you don’t want the above condition, at first you turn on UC864-E and then connect USB.
And when you want to turn off or shut down UC864-E, you have to cut off USB_VBUS power(disconnect USB) prior to pressing ON_OFF button.

Q - Can you confirm that your USB Client driver does not need Isochronous USB transfers?

A - The USB driver for UC864-E didn't use the isochronous USB transfer type. The driver utilized only Interrupt and bulk transfer types via three virtual ports.

Q - My customer doesn’t want to use the USB port for the data, is it possible to send small packets over the HSDPA channel to a UDP host via the RS232 port only?

A - Yes the UART port can be used to send data over HSDPA channel. The baudrate is limited to 230400 but for few packets it shouldn't be a problem.

Q – How do I connect to the UC864-G and enable the NMEA data?

A - First of all, please install the USB driver with the attached setup file. (NOTE: Go to our Telit Password Protected Website for the UM20 UC864 USB driver. If you don't have the login details and you are an Australian or NZ customer, please send us an email at

In the normal case, the UC864-G module creates following four virtual ports.

- CDC Data Modem Port : for the primary data port or data connection

- Diagnostic Port : for the external QXDM logging or firmware downloading

- Auxiliary Data Port : for the auxiliary data port or data connection,

   But this port mainly used as the supplementary port for receiving notification messages.

- NMEA port : for receiving the unsolicited streaming of GPS data in NMEA format.

Note that the connection manager program is only for UM20 modem.

So, we can't gurantee the normal operation of this tool on the UC series of modules.

In order to activate the unsolicited streaming of GPS NMEA data you have to assert AT$GPSNMUN=1,0,0,1,0,0,0


For its description, pls see the below table or refer to AT command Reference guide for UC864-E/G.

$GPSNMUN - Unsolicited NMEA Data Configuration





<RMC>,<VTG >]

Set command permits to activate an Unsolicited streaming of GPS data (in

NMEA format) through the standard GSM serial port and defines which

NMEA sentences will be available



0 - NMEA data stream de-activated (default)

1 - NMEA data stream activated with the following unsolicited response



2 - NMEA data stream activated with the following unsolicited response



3 - dedicated NMEA data stream; it is not possible to send AT commands;

with the escape sequence +++ the user can return to command mode

<GGA> - Global Positioning System Fix Data

0 - disable (default)

1 - enable

<GLL> - Geographical Position - Latitude/Longitude

0 - disable (default)

1 - enable

<GSA> - GPS DOP and Active Satellites

0 - disable (default)

1 - enable

<GSV> - GPS Satellites in View

0 - disable (default)

1 - enable

<RMC> - recommended Minimum Specific GPS Data

0 - disable (default)

1 - enable

<VTG> - Course Over Ground and Ground Speed

0 - disable (default)

1 - enable


Read command returns whether the unsolicited GPS NMEA data streaming

is currently enabled or not, along with the NMEA sentences availability

status, in the format:

$GPSNMUN:<enable>,<GGA>,<GLL>,<GSA>,<GSV>,<RMC>,<VTG >


Test command returns the supported range of values for parameters

<enable>, <GGA>, <GLL>, <GSA>, <GSV>, <RMC>, <VTG>




These sets the GSA as available sentence in the

unsolicited message



Turn-off the unsolicited mode


$GPSNMUN: 1,0,0,1,0,0,0


Give the current frame selected (GSA)

The unsolicited message will be:




NMEA 01803 Specifications

Q - I was wandering if you know if there is any option available on the UC864-G W-CDMA bands to set up a transparent serial comm’s link similar to a CSD connection on the GSM channel. I guess the question is that once I have made a call to another W-CDMA module is it possible to send and receive data like a normal serial port connection and if so is there anything I need to know in order to set this up?

A - For WCDMA network, you can place the synchronous transparent CS data call, by configuring following bear service types with the command +CBST,

1. Synchronous Transparent 64 kbps CS Data call
AT+CBST=116, 1, 0 // Bit transparent 64000 transparent

2. Multimedia 64 kbps CS Data call (Other Rate Adaptation in the BC-IE is set to H.223 and H.245)

AT+CBST=134, 1, 0 multimedia 64000 transparent

You can find these infos from the software user guide and AT reference guide for UC864-E/G.

But, AT+CBST=134,1,0 has been missed at the AT reference guide.

Maybe, this available setting will be appended in its next revison.

Note that for +CBST=134,1,0(Video Call), UC864-E/G module can support only its bearer and

the customer should implement the video telephony protocol(3G-324M) and its UI application, if necessary.

And UC864-E/G module can support SVD(Simultaneous Voice and Data) feature, regardless of CS or PS data call.