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The USB-HUB is self-powered, and two LTE modules are connected via USB-SERIAL to USB-HUB. We are facing a problem is that,The devices which are connected to USB-HUB can not be accessed. Is there any investigation method and solution for this?

Below following are kernel Logs.

Kerenl log:

19:47:58 raspberrypi kernel: [ 9301.001438] usb usb1-port1: disabled by hub (EMI?), re-enabling...

19:47:58 raspberrypi kernel: [ 9301.001457] usb 1-1: USB disconnect, device number 11

19:47:58 raspberrypi kernel: [ 9301.001463] usb 1-1.1: USB disconnect, device number 12

19:47:58 raspberrypi kernel: [ 9301.001668] ftdi_sio ttyUSB2: error from flowcontrol urb

19:47:58 raspberrypi kernel: [ 9301.001872] ftdi_sio ttyUSB2: FTDI USB Serial Device converter now disconnected from ttyUSB2

19:47:58 raspberrypi kernel: [ 9301.001906] ftdi_sio 1-1.1:1.0: device disconnected

19:47:58 raspberrypi kernel: [ 9301.002107] ftdi_sio ttyUSB3: error from flowcontrol urb

19:47:58 raspberrypi kernel: [ 9301.003371] ftdi_sio ttyUSB3: FTDI USB Serial Device converter now disconnected from ttyUSB3

19:47:58 raspberrypi kernel: [ 9301.003429] ftdi_sio 1-1.1:1.1: device disconnected

19:47:58 raspberrypi kernel: [ 9301.010150] ftdi_sio ttyUSB4: FTDI USB Serial Device converter now disconnected from ttyUSB4

19:47:58 raspberrypi kernel: [ 9301.010212] ftdi_sio 1-1.1:1.2: device disconnected

19:47:58 raspberrypi kernel: [ 9301.010430] ftdi_sio ttyUSB5: error from flowcontrol urb

19:47:58 raspberrypi kernel: [ 9301.018012] ftdi_sio ttyUSB5: FTDI USB Serial Device converter now disconnected from ttyUSB5

I will appreciate your help and time

Dirk
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Praveen Deshmane
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1 Answers1

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Question

Setup = Rpi > USB HUB > USB TTL adapter/cable > 2 LTE modules.

Protocol = AT Commands.

Problem = LTE module not detected.

Question = Any investigation method and solution?

Answer

  1. First test one module, not two.

  2. First test Rpi UART, not USB/UART.

  3. First test Rpi hardware/software using a simple loop back program.

  4. If Rpi UART ok, then test USB UART loopback.

  5. First test USB UART without HUB, then with HUB.

  6. First test simple request AT, response OK, then test rest.

Update 2019may24hkt1342

Now about the hub problem.

  1. Not all hubs are compatible with Rpi.

  2. Even if the hub is OK, not all USB UART/serial adapters/cable works with it well. I found most adapters with CH340 and PL2000 driver good with Rpi3B+ stretch 9.

  3. If in doubt, try connect the serial device direct to Rpi's standard USB sockets. For Rpi Zero without stand USB sockets， then try your luck with another USB hub.

You can also using linux terminal command "lsusb" to make sure if USB hub is detected.

usb hub detection

References

Testing Rpi UART serial loopback

Testing USB UART serial loopback

How to setup USB UART serial ports

AliExpress 4G LTE Module with serial port

GPRS/GSM/Heyes AT Commands Reference - Telit

GPS AT Command Reference - Option Wireless

Raspberry Pi GSM Module – Mobile Internet (LTE, 3G, UMTS)

The Raspberry Pi can be connected to the Internet very quickly and easily via the local network. But what if you also need a mobile Internet connection outside your own WLAN? There are GSM modules / Surfsticks (mostly from Huawei), which can be connected via USB. Sometimes are such GSM modules, which support 3G, UMTS and sometimes even LTE, given free with a mobile phone contract which includes an Internet option.

This tutorial shows how to connect Raspberry Pi to the internet using GSM modules.

If there is not something like Bus 001 Device 008: ID xyz ... standing, the GSM module on the Raspberry Pi has not yet been recognized.

So we need to install appropriate drivers.

tlfong01
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  • Thank you so much for your reply .

    Today we tried with single port but we faced the same problem like below. 19:47:58 raspberrypi kernel: [ 9301.001438] usb usb1-port1: disabled by hub (EMI?), re-enabling...

    So the error "Disabled by hub (EMI?)" is the impact of Noise or Static electricity? Can you please tell me. I am awaiting for your answer.

     – Praveen Deshmane May 24 '19 at 05:38
  • Well very little chance of noise or static electricity problem. More likely the hub itself has a problem. Do you have any USB serial adapter/cable to test, instead of the LTE module? Also see my answer updated just now. – tlfong01 May 24 '19 at 05:52
  • You can also use terminal command "lsusb" to make sure if USB hub is detected. One more thing, you can debug LTE module without using Rpi python program, but use terminal emulator RealTerm under Windows 7/10 to talk to lte device. In other words, isolate Rpi and use Windows RealTerm to check if LTE module can talk AT commands. Of course you can also use Rpi puTTY instead of Windows puTTY/TeraTerm/RealTerm. – tlfong01 May 24 '19 at 07:57
  • Not sure which LTE module you are using. Is it similar to the following: Raspberry Pi GSM Module – Mobile Internet (LTE, 3G, UMTS) https://tutorials-raspberrypi.com/raspberry-pi-gsm-module-mobile-internet-lte-3g-umts/ – tlfong01 May 27 '19 at 01:51

  • We are evaluating using CM3.

  • USB hub and USB-UART are boarded on the IO board.

  • USB hub is working in Self-power mode.

  • VBUS-detect of USB-hub uses the same 3.3V power supply as CM3.

  • Set correctly when in Power-On.

    • – Praveen Deshmane May 27 '19 at 05:28
  • Ah, I did not know that you are using CM3 with USB Hub and USB-UART on board, and CM3 self diagnostic and Rpi python loopback say everything OK. Then it is more likely that the LTE module has a problem. To isolate the root cause further, I would recommend to forget the CM3 thing for now and use Winodws7/10 Real Term to directly talk to the LTE module, As before, you (1) You make sure the Win Real Term can loop back OK, (2) try the LTE module, if no luck, then (3) Try Win RealTerm talk to Rpi puTTY, if this OK, then it it 90% likely that you LTE modules has a problem. – tlfong01 May 27 '19 at 06:02
  • I tried with all the above inputs, It is still not working. This problem occurs only sometimes not always. – Praveen Deshmane May 30 '19 at 04:44
  • Oh my goodness, intermittent failures are most difficult to troubleshoot. If it works even only once, then the software setup is OK. Then the hardware may have a hardware poor contact problem, or your LTE module it self is not reliable. If you can use Win Real Term to detect the LTE module, does it repeat EVERY TIME? Or you might like to show me pictures, like my GPS answer - https://raspberrypi.stackexchange.com/questions/98840/is-my-gps-module-fried The OP also has intermittent problem - sometimes his GPS modules can be detected, sometimes not! :( – tlfong01 May 30 '19 at 05:13
  • If you have two LTE modules, you might also like to use two Rpi's to compare and contrast the failure rates. I once tested 8 I2C MCP23017 modules at the same time, and I did statistics of their intermittent failure rate - Some good guy are almost zero percent failure rate, some are over 50%. :( – tlfong01 May 30 '19 at 05:21
  • This is the block diagram https://www.pinterest.com/pin/359443614011393442/ I hope you ll get more clear picture about the problem. – Praveen Deshmane Jun 02 '19 at 08:14
  • we are still facing the issue, is there any other solution. – Praveen Deshmane Jun 03 '19 at 06:10
  • Ah, let me see. Your block diagram is a bit confusing. To confirm: (1) You are using CM3, (2) CM3 has one USB hub, connected to two USB serial adapters, (3) You connect two LTE serial modules, one each to one of the USB serial adapters. – tlfong01 Jun 03 '19 at 06:19
  • Now let me suggest the following: (1) Remove both LTE serial modules from the CM3 > USB Hub > Two USB serial adapters. (2) Now just test the USB serial adapters by (a) using terminal commands to list the USB adapter device names, (b) For each USB serial adapter, connect TxD to RxD, and use a my python loopback test program or any similar program to make sure the USB serial adapters can loop back. – tlfong01 Jun 03 '19 at 06:24
  • does it happening because of noise? or might be a problem with not having sufficient decoupling caps on the board? – Praveen Deshmane Jun 03 '19 at 06:43
  • Well, try the loopback thing first. – tlfong01 Jun 03 '19 at 07:04
  • raspberrypi kernel: [14247.511414] mmc0: timeout waiting for hardware interrupt. I am facing this problem with flash memory CARD. – Praveen Deshmane Feb 15 '22 at 06:53
  • Well, I did find some hubs do not work, but other do. So I had no choice but change the hub. – tlfong01 Feb 15 '22 at 07:07