[Ovmsdev] 3G network

Mark Webb-Johnson mark at openvehicles.com
Fri Jun 21 19:23:16 HKT 2019


Our modem design was loosely based on some suggestions from SIMCOM. Like:

https://simcom.ee/documents/SIM7100E/SIM7100_SIM5360_SIM800C%20Compatible%20Design_V1.01.pdf <https://simcom.ee/documents/SIM7100E/SIM7100_SIM5360_SIM800C%20Compatible%20Design_V1.01.pdf>

I did get a SIM7100 module a year or two ago, and did some basic testing with it, but cost was just too high at that time. I will ask again to see where we are today. A quick check on aliexpress shows the SIM7100E at US$50 per module, and SIM5360E at US$20, in quantities of 1.

My main concern is software support. On paper, the SIM7100 looks compatible, and the AT commands very close. But the same was true of the SIM7000 I tried, and that was a mess - it seems the first firmware didn’t even support the MUX mode we rely on.

Given all the passive components required, it is probably easiest to just use a SIM5360 board, unsolder the modem module and replace it, then add / move that one antenna. To get my china contacts to make 3 one off boards is probably about the same price. In general, it is easy to get 1 or 1,000, but quantities in between are the issue.

Regards, Mark.

> On 21 Jun 2019, at 12:49 AM, Craig Leres <leres at xse.com> wrote:
> On 2018-06-12 15:26, Mark Webb-Johnson wrote:
>> Very easy to make. Our current modem circuit board layout actually supports both the SIM5360 (3G) and SIM7100 (4G) SIMCOM modules; we can simply drop in the appropriate module during production, and build with either 3G or 4G. If there is demand, we can satisfy within weeks
> What is my easiest path to getting a small quantity of ovms modem cards with SIM7100A modems? I probably only need 3, should I just buy some SIM5360A ovms boards and swap the simcom modules? And I guess move or add an antenna connector? I've attached a png version of a image from the message I'm replying to. It shows the SIM5360A using ANT1 and ANT3 while the SIM7100E uses ANT1 and ANT2 (and I see now the silkscreen documents this difference).
> 		Craig	
> <PastedGraphic-2.png>

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