/**
* @page TellStick TellStick protocol
*
* \section Introduction
*
* Telldus TellStick protocol looks like:
* [prefix[prefix parameters]][command][parameter 1]..[parameter n]['+']
*
* Each value in [ and ] is representing one byte.
*
* Command is one ascii character. Not all commands have parameters which
* makes it optional. Prefix is always optional.
* Note: Due to memory limitations, the parameters is limited in length to 79
* bytes.
*
* An example command to turn on a ArcTech codeswitch A1 may look like:
* S$k$k$k$k$k$k$k$k$k$k$k$k$k$k$k$k$k$k$kk$$kk$$kk$$}+
*
* TellStick returns to a known command like this:
* ['+'][command][parameters][13][10]
*
* [13] and [10] are the ascii characters 10 and 13.
*
* An example to query a TellStick on its firmware version:
* Command:
* V+
* Response:
* +V2
* The TellStick in the example has the firmware version 2.
*
* \section Commands
*
* \subsection sec_send S - Send command
* This command tells TellStick to send a command. The parameters to this
* command is the data-packet to send.
*
* Each of the characters in the parameters makes the antenna alternate
* high/low/high etc. The time before the alternation is 10 us timer the ASCII
* value. For example, $ has the ascii-value 36 and k has 107. The command:
* ['S']['$']['k']['$']['k']['$']['+'] makes the following wavepattern on the antenna:
*
* _____ _____ _____
* | | | | | |
* | | | | | |
* | |_______________| |_______________| |
*
* |<===>|<=============>|<===>|<=============>|<===>|
* 360us 1070us 360us 1070us 360us
*
*
*
* \subsection sec_send_extended T - Send command, extended
*
* The extended command was developed to overcome the limitations och the
* length of the data to 79 bytes.
* The idea is to have four fixed times on the pulses so the information about
* what to send only needs 2 bits instead of 8 in the command S
*
* The parameters to the command is:
* [t0][t1][t2][t3][length][d1]..[dn]
*
* t0-t3: Times 1 to 4. The times are in the same form as S.
* Each time is multiplied with the factor of 10.
*
* length: How many pulses to send. Since the data sent to TellStick
* is sent in groups of four pulses (one byte) and the actual data might not
* have pulses even divided with four.
*
* d1..dn: Each byte is the description for four pulses.
*
* Example:
* ['T'][127][255][24][1][6][98][80]['+']
*
* T: Send extended.
*
* 127,255,24,1: Times 1270 us, 2550 us, 24 us and 10 us
*
* 6: Six pulses to send.
*
* 98,80: The data in binary is 10011000,10000000. If
* we group it in groups of two bits we get 10 01 10 00 10 00 00 00.
* Since the length is only six pulses the last two pulses is discarded, giving:
* 10 01 10 00 10 00.
*
* Matching those bits to the times gives the following times:
* 10 => 2 => t2 => 240 us
* 01 => 1 => t1 => 2550 us
* 10 => 2 => t2 => 240 us
* 00 => 0 => t0 => 1270 us
* 10 => 2 => t2 => 240 us
* 00 => 0 => t0 => 1270 us
*
* This is equal if you used S:
* ['S'][24][255][24][127][24][127]['+']
*
* \subsection sec_version V - Firmware version
* This command queries the TellStick on its firmware version.
*
* Example:
* » V+
* « +V2
* \section Prefixes
* The prefixes are commands that can be prepended before some of the commands
* and cannot be used standalone. They are used to alter the behavior of the
* command.
*
* \subsection sec_debug D - Debug
* \subsection sec_pause P - Pause
* The pause is how low TellStick will wait between two packets. The value is
* in ms.
*
* Example, % has the ascii-value 37. The following packet will be sent with a
* pause of 37 ms between the packets:
* » P\%S$k$k$+
*
* \subsection sec_repeat R - Repeat
* This tells TellStick how many times to send the packet.
*
* Example, ! has the ascii-value 33. The following packet will be sent 33
* times:
* » R!S$k$k$+
*/