HardwareCP210xTutorial » History » Version 7
laforge, 02/19/2016 10:48 PM
1 | 1 | steve-m | == CP210x High Baudrates Tutorial == |
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2 | 6 | steve-m | [[Image(cp2102.jpg, right, 33%)]] |
3 | 1 | steve-m | 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. |
4 | 7 | laforge | |
5 | 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 [http://shop.sysmocom.de/products/cp2102-25 shop.sysmocom.de] |
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8 | So far this tutorial has only been tested with the CP2102, but this seems to be the most common chip anyway. |
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9 | 1 | steve-m | |
10 | === How it works === |
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11 | |||
12 | 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. |
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13 | 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. |
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14 | |||
15 | If you have a [wiki:PirelliDPL10 Pirelli DP-L10] you don't need to continue, the CP2102 in the phone has those mappings already preprogrammed. |
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16 | |||
17 | === Programming non-standard mappings === |
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18 | |||
19 | First of all you need to download and unpack the lastest version of [http://cp210x-program.sourceforge.net/ 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). |
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20 | |||
21 | To make sure cp210x-program will be the only one talking to the converter, unload the kernel module: |
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22 | |||
23 | {{{ |
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24 | sudo rmmod cp210x |
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25 | }}} |
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26 | |||
27 | After that, perform a dry-run to see everything is okay: |
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28 | |||
29 | {{{ |
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30 | sudo ./cp210x-program |
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31 | }}} |
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32 | |||
33 | The tool should output the device-string of the converter, some other information, and a baudrate table with the following default entries: |
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34 | {{{ |
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35 | [baudrate table] |
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36 | [...] |
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37 | 921600 = FFE6, FFF6, 1 # 923077 Baud, 20 us |
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38 | [...] |
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39 | 460800 = FFCC, FFEC, 1 # 461538 Baud, 40 us |
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40 | [...] |
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41 | 230400 = FF98, FFD9, 1 # 230769 Baud, 78 us |
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42 | [...] |
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43 | 115200 = FF30, FFB2, 1 # 115385 Baud, 156 us |
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44 | [...] |
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45 | }}} |
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46 | |||
47 | Okay, now to the real thing: create a backup of the EEPROM: |
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48 | |||
49 | {{{ |
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50 | sudo ./cp210x-program -f eeprom.hex |
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51 | }}} |
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52 | |||
53 | The next step is to program the modified, non-standard baudrates: |
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54 | |||
55 | {{{ |
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56 | 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 |
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57 | }}} |
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58 | |||
59 | 3 | steve-m | Check if the entries have been written successfully: |
60 | 1 | steve-m | |
61 | {{{ |
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62 | sudo ./cp210x-program |
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63 | }}} |
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64 | |||
65 | You should see the following entries: |
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66 | |||
67 | {{{ |
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68 | [baudrate table] |
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69 | [...] |
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70 | 812500 = FFE2, FFF4, 1 # 800000 Baud, 24 us |
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71 | [...] |
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72 | 406250 = FFC5, FFE9, 1 # 406780 Baud, 46 us |
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73 | [...] |
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74 | 203125 = FF8A, FFD3, 1 # 203390 Baud, 90 us |
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75 | [...] |
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76 | 115200 = FF30, FFB2, 1 # 115385 Baud, 156 us |
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77 | [...] |
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78 | }}} |
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79 | |||
80 | Replug the converter and you're done. |
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81 | |||
82 | === Using burst_ind === |
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83 | |||
84 | 4 | steve-m | If you want to use the burst_ind branch with a CP210x converter, you need to add the following define in osmocon.c: |
85 | {{{ |
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86 | #define I_HAVE_A_CP210x |
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87 | }}} |