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h2. CP210x High Baudrates Tutorial

!{width:33%}cp2102.jpg!

This page will describe the procedure of programming high, non-standard baudrate mappings to a SiLabs CP210x serial converter using Linux, needed by the burst_ind branch.

Small adapter PCBs to which you have to solder your own cable + plug can be bought quite cheaply on eBay and AliExpress. Ready-made adapter cables with the CP2102 can be bought from "shop.sysmocom.de":http://shop.sysmocom.de/products/cp2102-25

So far this tutorial has only been tested with the CP2102, but this seems to be the most common chip anyway.

h3. How it works

Contrary to the FTDI converters, non-standard baudrates can't be directly requested when opening the port, but need to be stored in the EEPROM of the device, overwriting the default entries.

So it works like this: You open the port with a standard baudrate, the converter performs a look-up in the baudrate-table of its EEPROM and uses the non-standard mapping you programmed.

If you have a [[PirelliDPL10|Pirelli DP-L10]] you don't need to continue, the CP2102 in the phone has those mappings already preprogrammed.

h3. Programming non-standard mappings

First of all you need to download and unpack the lastest version of "cp210x-program":https://github.com/VCTLabs/cp210x-program, an open-source tool replacing the proprietary windows-only tool from SiLabs (see application note AN205 if you want to mess with that).

To make sure cp210x-program will be the only one talking to the converter, unload the kernel module:

<pre>

sudo rmmod cp210x

</pre>

After that, perform a dry-run to see everything is okay:

<pre>

sudo ./cp210x-program

</pre>

The tool should output the device-string of the converter, some other information, and a baudrate table with the following default entries:

<pre>

[baudrate table]

[...]

 921600 = FFE6, FFF6, 1 #  923077 Baud, 20 us

[...]

 460800 = FFCC, FFEC, 1 #  461538 Baud, 40 us

[...]

 230400 = FF98, FFD9, 1 #  230769 Baud, 78 us

[...]

 115200 = FF30, FFB2, 1 #  115385 Baud, 156 us

[...]

</pre>

Okay, now to the real thing: create a backup of the EEPROM:

<pre>

sudo ./cp210x-program -f eeprom.hex

</pre>

The next step is to program the modified, non-standard baudrates:

<pre>

sudo ./cp210x-program -p -F eeprom.hex -w --set-baudrate 812500:FFE2,FFF4,1 --set-baudrate 406250:FFC5,FFE9,1 --set-baudrate 203125:FF8A,FFD3,1

</pre>

Check if the entries have been written successfully:

<pre>

sudo ./cp210x-program

</pre>

You should see the following entries:

<pre>

[baudrate table]

[...]

 812500 = FFE2, FFF4, 1 #  800000 Baud, 24 us

[...]

 406250 = FFC5, FFE9, 1 #  406780 Baud, 46 us

[...]

 203125 = FF8A, FFD3, 1 #  203390 Baud, 90 us

[...]

 115200 = FF30, FFB2, 1 #  115385 Baud, 156 us

[...]

</pre>

Replug the converter and you're done.

h3. Using burst_ind

If you want to use the burst_ind branch with a CP210x converter, you need to add the following define in osmocon.c:

<pre>

#define I_HAVE_A_CP210x

</pre>