Re: [Paparazzi-devel] send massage question

[Jochen Rieger]

Ok, thanks. Where can i read which massages should work in target "ap"? Is the rest of my massage ok, inspecial the checksum calculation?

Regards.
Jochen

2012/1/13 Gautier Hattenberger <address@hidden>

Hello,

The sender id should be the id of the ground station, but has it has no effect for now, so it's not your problem.
The SET_ACTUATOR message is only working if you run the firmware "test_actuators" on your autopilot. It has no effect on the normal autopilot (target "ap").

Gautier

On 12/01/2012 15:17, Jochen Rieger wrote:

Hello, i want to understand the massage protocol. An example should be set servo massage.

In message.xml file is written:

<message name="SET_ACTUATOR" id="100" link="forwarded">
   <field name="value" type="uint16"/>
   <field name="no" type="uint8"/>
   <field name="ac_id" type="uint8"/>
 </message>

Its meaning set servos, or isnt?

Next, was to define a massage:

99 0B 01 64 07 03 B6 01 01 27 AC


A PPRZ_STX                  99
B lenght A->E                 0B     = 11
C PPRZ_Data:               
  0 Sender_ID                 01    =aircraft id = 1
  1 Msg ID                       0x64 =100= massage id for set_actuator
  2 MSG Payload             07 = 7
  3 Data:
     a Value                       03 B6 = 950 (PWM)
     b No                           01 = second servoconnector has number 1
     c ac_id                       01 = sender_id???

D Checksum A (sum[B->C])  =  27
E Checksum B (sum[ck_a])   =  AC

Pprz frame:
 *
 *   |STX|length|... payload=(length-4) bytes ...|Checksum A|Checksum B|

where checksum is computed over length and payload:
 *     ck_A = ck_B = length
 *     for each byte b in payload
 *       ck_A += b; ck_b += ck_A

ck_a = ck_b = 11

b=1
ck_a= 12
ck_b= 23

b = 2
ck_a=14
ck_b=37

b= 3
ck_a=17
ck_b=54

b=4
ck_a=21
ck_b=75

b=5
ck_a=26
ck_b=101

b=6
ck_a=32
ck_b=133

b=7
ck_a=39
ck_b=172


Is there a mistake or complete false?
I have send this massage over gtkterm....but the elevator servo do not react.
Do i need define massages in my telemetry .xml file? I use default_fixedwing_imu.xml.

Thanks for any help.
Best regards.
Jochen

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