Voltage of the sim card
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Hello,
I would just like to make sure that the sim card I have been sent by you within the free account services will operate properly with my Waveshare Pico SIMCom 7080 board (the only card it is going to operate with is a 1.8V one, according to the datasheet).
I am asking since I have been having problems with persuading it to work on the 7080 board. The other one I have (Waveshare SIMCom Pico 7020 board) operates on both 1.8/3.3 V sim card (the datasheet says that), and I don’t have any problems with it.
Best regards,
Mariusz -
Hello @Mariusz2482
I have used the SIM card successfully in both SIMCom 7020G and SIMCom 7080G. (I use the corresponding offerings from M5Stack.)
What is the issue you are having with your SIMCom 7080 board which leads you to think it could be related to the SIM card?
Thanks
Felix -
Hi @fm
My problem with it is that I cannot make it (7080) start to communicate through UART (so that I can send AT commands to it).
The layout of the two boards (both prepared to work with Raspberry Pi Pico) is exactly the same (at least this is what I think is true),
although the two models differ significantly, and use two different sets of AT commands.
I have no idea what it may be caused by (and the first obvious technical difference between the two is the voltage of the SIM card they approve of).But it might also have something to do with waking it up, I think.
Thank you,
Mariusz -
Hello @Mariusz2482
on the SIM7020 board the PWRKEY is permanently connected to GND which automatically powers the SIM7020 modem on. See schematic here.
In contrast on the SIM7080 board the PWRKEY is connected (through a transistor) to pin 19 on the connector and named PWR_EN (See schematic). Pin 19 corresponds to GP14 (See here : Pinout Definition).
So in order for the SIM7080 modem to turn on you need to send a LOW-HIGH-LOW pulse to GP14 (See here : section 3.2 Power on/Power off function).
Thanks
Felix -
Hello @fm
In the first place, thank you for your time and involvement.
Sorry for keeping you waiting.
The information you provided has been very useful, as it turned out I have managed to wake the 7080 up from sleep. The Net LED started pulsing.
What is strange, I am still unable to receive any response from the 7080 after sending it the AT command, although the same wiring works perfectly with the 7020. It must have someting to do with voltage levels, I think (the SIM card voltage has nothing to do in this case). I am still trying to figure it out.
Best regards,
Mariusz -
Hello @Mariusz2482
I think for the SIM7080 you’ll need to provide 3.3 V to pin 36 on the connector which is labelled 3.3V(Out) else the voltage level shifter is not powered on the high side.
Thanks
Felix -
Hi @fm
@fm said in Voltage of the sim card:
for the SIM7080 you’ll need to provide 3.3 V to pin 36 on the connector which is labelled 3.3V(Out) else the voltage level shifter is not powered on the high side.
This is exactly what has been missing in my attempts. Following your advice resulted in my making it work at last.
Thank you once again.
Best regards,
Mariusz -
Hello @Mariusz2482
you are very welcome. I am glad to hear you got it working to your liking.
Thanks
Felix