LTE antenna not working on board



  • When i use the fipy on a the extension board, the LTE works but on my PCB it doesnt work. Is there a LTE pin that should not be connected?



  • Found the issue, appears like the pcb regulator causing the issue.



  • @misterlisty An input voltage of 4.82V is fine. The Vin range goes down to 3.6V, assumed, that the impedance of the power source is low. I have a home brew expansion board here with a polarity protection diode at Vin, and Vin is 4.65V. LTE works fine.
    If you have an oscilloscope, monitor the Voltage at Vin for short drops. Taking the power with a volt meter does not show fast fluctuations.
    What kind of LTE antenna are you using?



  • If i just connect pin 1,2 on the pycom from my board, it still fails to connect. It must be the power supply. The pycom ext board is providing 5.0 volts, my board is suppylinh 4.82v. This MUST be the cuase..nothing else is different! Very weird?



  • Not sure what you mean by "my PCB"...have you designed your own and if so, does it have all the necessary components to interface with the FiPy?



  • Fipy works fine. See the LTE commands..if i run this pycom from the extension board it work!

    -- START - INITILAISE LTE -------------------------------------------------------
    [ AT+SQNOMAHDEV? ] => ['', '+SQNOMAHDEV: 0,0,HUID0', '+SQNOMAHDEV: 0,1,HMAN0', '+SQNOMAHDEV: 0,2,HMOD0', '+SQNOMAHDEV: 0,3,HSW0', '+SQNOMAHDEV: 1,0,HUID1', '+SQNOMAHDEV: 1,1,HMAN1', '+SQNOMAHDEV: 1,2,HMOD1', '+SQNOMAHDEV: 1,3,HSW1', '', 'OK', '']
    | +SQNOMAHDEV: 0,0,HUID0 | +SQNOMAHDEV: 0,1,HMAN0 | +SQNOMAHDEV: 0,2,HMOD0 | +SQNOMAHDEV: 0,3,HSW0 | +SQNOMAHDEV: 1,0,HUID1 | +SQNOMAHDEV: 1,1,HMAN1 | +SQNOMAHDEV: 1,2,HMOD1 | +SQNOMAHDEV: 1,3,HSW1 | | OK | | [ AT+SQNOMAHDEV=? ] => ['', '+SQNOMAHDEV: (0-1),(0-3),"value"', '', 'OK', '']
    | +SQNOMAHDEV: (0-1),(0-3),"value" | | OK | | [ ATI1 ] => ['', 'UE5.0.0.0d', 'LR5.1.1.0-41065', '', 'OK', '']
    | UE5.0.0.0d | LR5.1.1.0-41065 | | OK | | None
    LTE set to
    +SQNCTM: telstra

    OK

    Feed hardware watchdog and blink..
    heatbeat suspended while BLE connected
    [ AT!="clearscanconfig" ] => ['', '', 'OK', '']
    | | OK | | [ AT+CGDCONT=1,"IP","telstra.m2m" ] => ['', 'OK', '']
    | OK | | [ AT!="addscanfreq band=28 dl-earfcn=9410" ] => ['', '', 'OK', '']
    | | OK | | [ AT+CEREG=2 ] => ['', 'OK', '']
    | OK | | [ AT+CFUN=1 ] => ['', 'OK', '']
    | OK | | Tones Done
    Feed hardware watchdog and blink..
    heatbeat suspended while BLE connected
    LTE Appear not be connected
    [ AT+COPS=? ] => ['', 'ERROR', '']
    | ERROR | | [ AT+CSQ ] => ['', '+CSQ: 99,99', '', 'OK', '']
    | +CSQ: 99,99 | | OK | | Attempting to attach to LTE ....... LTE successfully connected to network..
    LTE attached to
    +SQNCTM: telstra

    OK

    LTE RSSI: -83 dbM
    -- START - INITILAISE LTE -------------------------------------------------------
    'InitCellular..done'



  • @misterlisty You can see at the FiPy Pin-Out which ins are needed by the LTE modem. its P15, P17 - P20. Besides LTE, does the FiPy seem to work fine?
    p.s.: I do not under stand "LTE antenna". The LTE antenna must be plugged to the FiPy, wherever you put the FiPy at.


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