On Fri, Mar 11, 2016 at 04:10:24PM -0600, Dan Williams wrote: > On Fri, 2016-03-11 at 19:17 +0100, Marcin Szewczyk wrote: > > [...] I am working on a phone-like device that could make a voice > > call and sometimes send some data over the internet. I am confused, > > probably because most of documentation on voice modems is from > > another century.
> There are a couple different classes of devices here. > > First you have typical dongles and mPCI/mPCIE/M.2 cards that use USB. > Not all of these devices support voice calls though. But the ones > that do typically expose a normal serial port (eg, ttyUSB3 or > whatever) that speaks PCM audio. [...] One example is the Huawei > K3520 USB dongle; many other Huawei dongles have voice support too. > > But the modems usually found in embedded devices or phones have much > different audio call routing, often because they don't use the main > CPU for audio processing due to power/battery concerns. In these > cases the modem itself handles the audio and is directly connected to > the DAC/ADC. [...] My colleague had found a versatile device suitable for embedded solutions. I have tested its EVB version. I thought it might be interesting for anybody that finds this thread. A Simcomm 7100E chip has LTE and comes in 3 versions: - as a chip, - as a mPCIe card, - as a development board (EVB). > The QMI and MBIM commands are only used to set up the voice calls, but > don't have any relationship to audio routing. That would be modem > dependent. Some have specific pins/lines for the audio, others direct > it over USB, etc. > It does look like some mPCI devices do support I2S on the same pins, > but I have no idea if any of this is standard. > > http://www.telit.com/index.php?eID=tx_nawsecuredl&u=0&g=0&t=1457821946&; > hash=9f7b2671f9068c04d6ca770e04187bedbdf4e7b5&file=downloadZone/1VV0301 > 006_xE910_Mini_PCIe_Adapter_HW_USER_GUIDE_r10.pdf > > http://www.eltech.spb.ru/files/item/MC8704.pdf The chip by itself can send and receive digital audio through: - PCM pins; on mPCIe it uses odd 45-51 pins -- same as the mentioned Telit and Sierra modems, - ttyUSB after issuing an AT command; it works with PCM 16bit, 8kHz, Mono, LE. Additionally when using the EVB, mPCIe (probably) or a self-developed board with an added codec (ADC/DAC) it can send/receive analog audio through 1 of 3 channels selected with AT commands. On electrical level selection is done using I2C communication with the codec (WM8960 on the EVB). Manufacturer's website: http://simcomm2m.com/En/module/detail.aspx?id=86 Russian (distributor's?) website with lots of documentation: http://mt-system.ru/catalog/besprovodnye-reshenija/gsm-moduli-simcom/linejka-modulej-i-dokumentacija/sim7100e-pci-e The chip is supported in newer kernels via the option module. Older kernels are easily patchable: https://github.com/torvalds/linux/commit/3158a8d416f4e1b79dcc867d67cb50013140772c Establishing a data connection worked with pppd and Modem Manager 1.5. Voice connections probably require some simtech plugin patching. I haven't debugged it sufficiently yet. -- Marcin Szewczyk http://wodny.org _______________________________________________ ModemManager-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/modemmanager-devel
