[STM32L073RZT6] Read USB pins from GPRS modem

[Modiot Modiot]

Posted on April 03, 2018 at 13:33

Hello everybody,

I would like to read the USB_DM and USB_DP pins from a GPRS module (it only works in Device mode) with the STM32L073RZT6 microcontroller which has also USB pins available. However, I realized that it only works as device mode too, so I do not know if there is any way to implement my idea with this microcontroller.

I would appreciate any help.

Thanks!

Best regards,

[waclawek.jan]

Posted on April 03, 2018 at 16:41

You want to connect the module to STM32 as if the STM32 would be a PC?

JW

[Tesla DeLorean]

Posted on April 03, 2018 at 16:56

>>

However, I realized that it only works as device mode too, so I do not know if there is any way to implement my idea with this microcontroller.

No, reading and deciphering a 12Mbps signal on the USB pins is not a practical task for you to undertake. Think about using a different part. Or a GPRS modem that uses a USART.

[Modiot Modiot]

Posted on April 03, 2018 at 17:00

Yes, I do. 

The module dumps traces in this USB interface, so I would like to read these traces using the microcontroller. Under my understanding, it is needed an OTG USB in order to configure it as 'host' (this microcontroller has not OTG USBs), is not it?

Thanks!

[Modiot Modiot]

Posted on April 03, 2018 at 17:04

Thanks for your answer.

This module has one UART which I use to transfer data during TCP connections, but I would like to have another interface to monitor unsolicited module messages (for example error connections, SIM remove...) and only a USB interface is available. For this reason, I was trying to find that solution.

Thanks.

[Tesla DeLorean]

Posted on April 03, 2018 at 17:17

Find a modem supporting CMUX protocol

[Modiot Modiot]

Posted on April 04, 2018 at 09:23

Thanks so much!

I did not know this protocol and it seems to be the best solution.

Thanks!

Best regards,

[Andrew Neil]

Posted on April 04, 2018 at 10:16

Modiot Modiot wrote:

monitor unsolicited module messages (for example error connections, SIM remove...)

But, in any of those cases, the TCP connection will drop anyhow - so you will be back in AT Command mode!

[Modiot Modiot]

Posted on April 10, 2018 at 08:37

Yes, it is, but using another interface I could monitor all those unsolicited messages.

Thanks for you reply!