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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 install download and unpack the latest 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). This can be done using the Python's package manager:
<pre>
sudo pip install git+https://github.com/VCTLabs/cp210x-program.git
</pre>
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 ./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 ./cp210x-program -f eeprom.hex
</pre>
The next step is to program the modified, non-standard baudrates:
<pre>
sudo cp210x-program ./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 ./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>
