Can’t get Fibocom NL678-E LTE modem serial ports working after sending AT+GTUSBMODE=22

Installing and Using OpenWrt
1

To get that modem working under OpenWrt i tried sending the AT+GTUSBMODE=22 command like someone wrote here,

but then i got the following message:

FATAL: read zero bytes from port
term_exitfunc: reset failed for dev UNKNOWN: Not a tty

so i looked at ls /dev

bus        log        mtd4       mtdblock3  random     ttyS11     ttyS6
console    mtd0       mtd4ro     mtdblock4  shm        ttyS12     ttyS7
fd         mtd0ro     mtd5       mtdblock5  stderr     ttyS13     ttyS8
full       mtd1       mtd5ro     mtdblock6  stdin      ttyS14     ttyS9
gpiochip0  mtd1ro     mtd6       null       stdout     ttyS15     urandom
gpiochip1  mtd2       mtd6ro     port       tty        ttyS2      watchdog
gpiochip2  mtd2ro     mtdblock0  ppp        ttyS0      ttyS3      watchdog0
hwrng      mtd3       mtdblock1  ptmx       ttyS1      ttyS4      zero
kmsg       mtd3ro     mtdblock2  pts        ttyS10     ttyS5

and tried to cat /sys/kernel/debug/usb/devices if it still showed the device:
it did.

T:  Bus=01 Lev=02 Prnt=02 Port=02 Cnt=01 Dev#=  3 Spd=480  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=2cb7 ProdID=0109 Rev= 3.10
S:  Manufacturer=Fibocom
S:  Product=Fibocom NL678-E Modem
S:  SerialNumber=12345678
C:* #Ifs= 3 Cfg#= 1 Atr=a0 MxPwr=500mA
I:* If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=82(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 1 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=84(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=86(I) Atr=03(Int.) MxPS=   8 Ivl=32ms
E:  Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms

Then i temporary tried to add (recover) it like someone wrote at mentioned thread with:
echo 2cb7 0109 ff > /sys/bus/usb-serial/drivers/option1/new_id

then indeed the Serial USB devices are shown again with ls /dev

ls /dev

bus        mtd0       mtd5       mtdblock6  stdout     ttyS2      ttyUSB2
console    mtd0ro     mtd5ro     null       tty        ttyS3      urandom
fd         mtd1       mtd6       port       ttyS0      ttyS4      watchdog
full       mtd1ro     mtd6ro     ppp        ttyS1      ttyS5      watchdog0
gpiochip0  mtd2       mtdblock0  ptmx       ttyS10     ttyS6      zero
gpiochip1  mtd2ro     mtdblock1  pts        ttyS11     ttyS7
gpiochip2  mtd3       mtdblock2  random     ttyS12     ttyS8
hwrng      mtd3ro     mtdblock3  shm        ttyS13     ttyS9
kmsg       mtd4       mtdblock4  stderr     ttyS14     ttyUSB0
log        mtd4ro     mtdblock5  stdin      ttyS15     ttyUSB1

but if i use picocom or minicom i cannot enter any text or commands anymore

i tried:

picocom /dev/ttyUSB2
microcom /dev/ttyUSB2

also tried with echo on then i can write text or commands but i dont get any response from the NL678-E Modem
TTYUSB0 and TTYUSB1 listed i also tried but no response anymore from the card,

echo -e "AT+GTUSBMODE=17\r\n" > /dev/ttyUSB2 also didn't helped as the modem seems not to accepts AT commands anymore.

nor to reset and power off/on the modem

it looks like the modem is (soft)bricked after using cmd AT+GTUSBMODE=22 :frowning:

is there any (other) way to unbrick?

2

Please use the </> button to wrap your cli output, when posting.

3

Your AT command port is now /dev/ttyUSB1
Use a proper terminal app instead of using echo.
Please reformat your post.

1 Like
4

Thank you very much, i used picocom before, then tried using echo when i got no response from the modem on TTYUSB0, TTYUSB1 and TTYUSB2, anyways it seems to work now after a hardreset.

5

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