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--- doc:crazyflie:crtp:param [2015-10-26 18:24]
arnaud
+++ doc:crazyflie:crtp:param [2015-12-10 09:46]
arnaud [Set by name]
@@ Line 2: / Line 2: @@
 The parameters system makes all the gettable and settable parameters of the copter accessible. The copter holds a table of parameters which can be retrieved. In this table every parameter name is associated with an ID and a group name. Three IDs are used to acces the TOC and the parameters:
-^ Port      ^ Channel     ^ Function          ^
+^  Port  ^  Channel  ^ Function          ^
-|  2        | 0           | TOC access        |
+|  2     |  0        | [[doc:crazyflie:crtp:param#toc_access|TOC access]]        |
-|  2        | 1           | Parameter read    |
+|  2     |  1        | [[doc:crazyflie:crtp:param#parameter_read|Parameter read]]    |
-|  2        | 2           | Parameter write   |
+|  2     |  2        | [[doc:crazyflie:crtp:param#parameter_write|Parameter write]]   |
+|  2     |  3        | [[doc:crazyflie:crtp:param#misc_command|Misc. commands]]    |
-===== TOC access (Port 2 channel 0) =====
+===== TOC access =====
 These messages permit to access the parameters table of content. The first byte of the message is a message ID, three messages ID are defined:
@@ Line 33: / Line 34: @@
 The CRC32 is a hash of the copter TOC. This is aimed at implementing caching of the TOC in the PC Utils to avoid fetching the full TOC each time the copter is connected.
-===== Parameter read (Port 2 channel 1) and parameter write (Port 2 channel 2) =====
+The type is one byte describing the parameter type:
-The following messages are sent from the client to the Crazyflie:
+^ Type code ^ C type ^ Python unpack |
-^  **Request for**   ^  **Byte**  ^  **Description**  ^
+| 0x08      | uint8_t | '<B' |
-|  Parameter read    |     0      | The id of the parameter to read   |
+| 0x09      | uint16_t | '<H' |
-|  Parameter write   |     0      | The id of the parameter to write   |
+| 0x0A      | uint32_t | '<L' |
-|   :::              |     1      | The value to set |
+| 0x0B      | uint64_t | '<Q' |
+| 0x00      | int8_t | '<b' |
+| 0x01      | int16_t | '<h' |
+| 0x02      | int32_t | '<i' |
+| 0x03      | int64_t | '<q' |
+| 0x05      | FP16 | '' |
+| 0x06      | float | '<f' |
+| 0x07      | double | '<d' |
-The following messages are sent from the Crazyflie to the client:
+===== Parameter read =====
-^  **Reply for**            ^  **Byte**  ^  **Description**  ^
-|  Parameter read & write   |     0      | Parameter id      |
+<WRAP group>
-|   :::                     |     1-n    | Parameter value   |
+<WRAP half column>
+^ Byte ^ Request fields ^ Content  ^
+|  0   | ID       | ID of the parameter to read (see TOC) |
+</WRAP>
+<WRAP half column>
+^ Byte ^ Answer fields  ^ Content  ^
+|  0   | ID       | ID of the parameter |
+|  1-..  | value | Value of the parameter. Size and format is described in the TOC |
+</WRAP>
+</WRAP>
+The read request is a simple packet on channel 1. Crazyflie answers with the value.
+===== Parameter write =====
+<WRAP group>
+<WRAP half column>
+^ Byte ^ Request fields ^ Content  ^
+|  0   | ID       | ID of the parameter to write |
+|  1-...   | value | Value to write. Size and format is described in the TOC |
+</WRAP>
+<WRAP half column>
+^ Byte ^ Answer fields  ^ Content  ^
+|  0   | ID       | ID of the parameter |
+|  1-...  | value | Value of the parameter. Size and format is described in the TOC |
+</WRAP>
+</WRAP>
+The write request is a simple packet on channel 2. Crazyflie sends back the parameter value as an acknowledgement.
+===== Misc. commands =====
+The following misc commands are implemented:
+^  Code  ^ Command ^
+|  0x00  | [[doc:crazyflie:crtp:param#set_by_name|Set by name]] |
+==== Set by name ====
+<WRAP group>
+<WRAP half column>
+^ Byte ^ Request fields ^ Content  ^
+|  0   | SET_BY_NAME       | 0x00 |
+|  1-n   | group | Name of the group |
+|  n-(n+1)  | NULL | 0 |
+|  (n+1)-(n+m+1)   | name | Name of the parameter |
+|  (n+m+1)-(n+m+2)  | NULL | 0 |
+|  (n+m+2)-(n+m+3)  | TYPE | Parameter type |
+|  (n+m+3)-...      | value | Value. Size and format is described by type |
+</WRAP>
+<WRAP half column>
+^ Byte ^ Answer fields  ^ Content  ^
+|  0   | SET_BY_NAME       | 0x00 |
+|  1-n   | group | Name of the group |
+|  n-(n+1)  | NULL | 0 |
+|  (n+1)-(n+m+1)   | name | Name of the parameter |
+|  (n+m+2)  | NULL | 0 |
+|  (n+m+3)  | ERROR | 0 if the parameter has been successfully written. Other code are taken from[[http://www.virtsync.com/c-error-codes-include-errno|errno C codes]]. |
+</WRAP>
+</WRAP>
+//Group// and //name// are ascii strings of size respectively //n// and //m//. The type corresponds to the TOC type of the parameter. It is checked for consistency.
+This command is useful to set a parameter without having to fetch the full TOC. It is enough to know the group, name and type of the parameter to write it.

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