Posts: 2
Joined: Sun Jul 06, 2014 10:52 pm

Re: 4G Hat

Wed Aug 04, 2021 6:56 am

For those of you who are running on Ubuntu (21.04 in my case) and can't get any of the qmcli commands to work because you get an errors like

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error: couldn't create client for the 'dms' service: CID allocation failed in the CTL client: Transaction timed out
error: couldn't create client for the 'dms' service: CID allocation failed in the CTL client: endpoint hangup
error: couldn't open the QmiDevice: Transaction timed out
Its because the ModemManager daemon (which enables the mmcli command) which automatically runs at least on Ubuntu Desktop, is conflicting with the qmcli stuff. This had me blocked for a couple of days trying to make the basics work with the SIM7600.

You can disable ModemManager with the commands:

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sudo systemctl unmask ModemManager.service # may need this
sudo systemctl disable ModemManager.service
That being said, it should be possible to make the SIM7600 work with the ModemManager, as some of the earlier posts describe. I haven't been able to do that yet, but will try as it looks like that could be a better way. You just can't have both (qmcli and ModemManager / mmcli) working at the same time as far as I can tell.

Posts: 10
Joined: Sun Dec 17, 2017 1:00 pm

Re: 4G Hat

Sat Aug 14, 2021 7:35 pm


I have a SIM7600E LTE HAT connected to a Raspberry Pi 3 B+ (Buster). Following various explanations and advice I have managed to succesfully send SMS through the AT command, I can also make phone calls. But I don't understand how do I use the device to surf on the Internet.

Can someone please advise ?

Thank you

Posts: 2
Joined: Tue Aug 31, 2021 6:03 pm

Re: 4G Hat

Tue Aug 31, 2021 6:21 pm

I'm planning on using a Raspberry Pi Zero plus a Waveshare SIM7600A-H 4G HAT where I don't have access to power so I'm going to use a solar panel with a LifePO4 battery. The device will only have to communicate back a couple of times an hour to just transmit a file.

In order to conserve power I'd like to put the SIM7600A-H into a low power mode between communications. Does anyone have experience putting the HAT into, then bringing it out, of a lower power mode? For my use, it is fine if it takes a few seconds to come back up. I figure the power savings of putting the HAT into low power mode for minutes at time, and bringing it up to transmit the file, then back to low power mode would be better than just leaving it in normal mode all the time. There are also hours (e.g. overnight) where I would just leave it in low power mode.

I also only need this for LTE data communication. Are there other functions that I could shut down (maybe GPS) to further save power?

Has anyone measured current draw of the LTE HAT under various conditions like, transmitting data receiving data, not sending receiving but also not in low power/sleep mode, and finally when in low power/sleep mode?

Posts: 2
Joined: Tue Aug 31, 2021 6:03 pm

Re: 4G Hat

Sat Sep 04, 2021 7:25 pm

In reply to my own post, I have my Waveshare SIM7600A-H 4G HAT working with my Raspberry PI Zero. With the daemons I have running, the current draw with my Raspberry PI without the Waveshare HAT attached is about 95 mA. With the Waveshare HAT running, and with LTE network connectivity, but no active IP traffic, the current draw is 145 mA. When there is active network traffic it spikes above 200 mA.

A few more tips for anyone trying to get one of these working with T-Mobile in the US, follow mkrzysztofowicz's instructions and the "--device-open-net" command is:

sudo qmicli -p -d /dev/cdc-wdm0 --device-open-net='net-raw-ip|net-no-qos-header' --wds-start-network="apn='fast.t-mobile.com',ip-type=4" --client-no-release-cid

No username or password needed.

Finally, I have the new hardware that released in 2nd 1/2 of 2021 so I set the side jumper so that I can control the power to the HAT from GPIO6. I just wrote a Python script with gpiozero and toggled GPIO6 High/Low/High/Low with 4 seconds in between transitions and HAT shut down. I reversed that (ending in High) to power the HAT back up. I found that simply taking GPIO6 Low wasn't enough the shut it down. There had to be a toggle both directions and ending either High (on) or Low (off).

Thanks to this thread it was pretty easy to get this running.

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