Modem returning bad characters, was working before Ubuntu upgrade

Question

My modem doesn't seem to work anymore, although it was working with Ubuntu 12.04, I upgraded to 13.04 and now it's not working...

When I tried to connect with minicom -s or probemodem (from hylafax) and run the ATI commands, I get garbage characters. I don't recall seeing that before. This happens whether I use the old set up or the new one. I have an internal modem and I can connect at 38400 with minicom. When I just do AT, I get the OK as expected. However, when I try an ATI command, I get garbage, then whatever I type shows up as garbage.

I tried to turn off the computer and back on, in case it needed a cold reset, and the same thing still happens.

Is there a known difference in handling internal modems between version 12.04 and 13.04 of Ubuntu? Or could it just be a bad communication setup (but how would AT + OK work and not the rest?!)

Note that Hylafax worked just fine and sent hundreds of faxes while I was on 12.04... I'd bet it would still work if I were to reinstall 12.04! It's just not an option at this point.

There are samples of the garbage I get. As we can see, in some cases we see "OK" or "ERROR" as the response, but most of the ATI functions return invalid characters.

ATI0    RESULT = "RʋW�.+
                     T,W��T/�S�VV
                                   �U���Z�
                                          R�    �VH�H�j�H�" RESPONSE = ""
ATI1    RESULT = "OK"   RESPONSE = ""
ATI2    RESULT = "AUJS�H�j�H�"  RESPONSE = ""
ATI3    RESULT = "RʋW�.+
                     T,W��T/�S�VV
                                   �U���Z�
                                          R�    �VH�H�j�H�" RESPONSE = ""
ATI4    RESULT = "OK"   RESPONSE = ""
ATI5    RESULT = "OK"   RESPONSE = "OCM Ver3.9/1.7,0,34"
ATI6    RESULT = "��ɽم��j�����jE�����Օ�H�H�j�H�"    RESPONSE = ""
ATI7    RESULT = "OK"   RESPONSE = ""
ATI8    RESULT = "OK"   RESPONSE = "OK"
ATI9    RESULT = "�&&KURP�M'ժ�ѥQ�������ѕ�́jQ咚���թ5*����T�H�H�j�H�"  RESPONSE = ""

AT+FCC=?    RESULT = "OK"   RESPONSE = "(0000-0FFF),(00-0D),(00-02),(00-02),(00-01,03-05,07-09,0B-0D,0F),(00-01),(00),(00-07),(00-7F)"
AT+FCC? RESULT = "A��j��j�b�ł�b��b��b��b��b��b��j��H�j�H�"  RESPONSE = ""
AT+FCQ=?    RESULT = "OK"   RESPONSE = "(00-01),(00)"

Just in case, changing the speed to 9600 and the transfer to 7N1 (7 bits, no parity, 1 stop) then I can get much better communications (all considered,) which look like this:

ATI0c
Agere OCM V.92 MT9234ZPX-UPCI Internal Data/Fax Modem Version 1.02d

This way at least the modem name, etc. are visible.

score 0 · Answer 1 · answered Sep 24 '13 at 04:29

Although I don't yet have a good final answer to this question, I have reasons to believe that the new kernel is the culprit. I rebooted with kernel version 3.5.0 (I believe 12.10) and everything works like a charm. At this point, doing so will solve your problem, although you certainly will want to run a newer kernel with your board.

I posted a bug on the Linux kernel website, I will see what I get as feedback. I certainly hope to properly solve the issue at some point. I may have to do some kernel debugging...

So, if your modem worked before, or you are trying to get your modem to work, make sure to boot with 12.10 or even 12.04 for now. You may upgrade to 13.10, but make sure to still run the older kernel when you need to use your fax/modem.

Modem returning bad characters, was working before Ubuntu upgrade

1 Answers1