CAN Bus protocol

This section defines the MEX communication protocol.

This is the configuration of messages that must be performed with Veronte Autopilot 1x to communicate with MEX.

Note

No configuration of these messages is required in MEX, as MEX is already internally configured to “understand” messages configured in this way.

Warning

For these messages sent from the Autopilot 1x to be processed correctly, they must be received by the ‘Consumer’ Application processor.

MEX Communication Protocol over CAN bus is defined as follows:

  1. cmd (8 bits - 1 byte): first byte refers to the Message Type.

    Messages Type are defined as follows:

    Type

    Value

    Description

    t_arbitration

    0

    Arbitration message

    t_version

    1

    Version request / response

    t_pwm_0_3_set

    2

    PWMs 0 to 3

    t_pwm_4_7_set

    3

    PWMs 4 to 7

    4

    Reserved

    t_esc_tm

    5

    Scorpion Tribunus ESC telemetry data

    t_esc_tm2

    6

    Jeti ESC telemetry data

    t_bec_tm1

    7

    Jeti BEC telemetry data 1

    t_bec_tm2

    8

    Jeti BEC telemetry data 2

    t_temp_tm

    9

    Jeti Temperature sensor telemetry data

    t_mcu_cmd

    10

    Lift MCU battery command

    t_pwm_8_11_set

    11

    PWMs 8 to 11

    t_pwm_12_15_set

    12

    PWMs 12 to 15

    t_pwm_16_19_set

    13

    PWMs 16 to 19

    14

    Reserved

    15

    Reserved

    t_cmd_maint

    16

    Command to go to Maintenance Mode

    t_stick_sel

    17

    Command for Stick selection

    t_mcu_tm1

    18

    Lift MCU telemetry data 1

    t_mcu_tm2

    19

    Lift MCU telemetry data 2

Note

All these Message Type are defined as a “Matcher” in the CAN custom messages configuration. For example, for PWMs 0-3, the Message Type will be configured as follows:

../_images/message_type_example.png

Message Type example

  • Value: 2, since it is the value for the message for PWMs 0 to 3 (it is indifferent to the PWM number).

  • Bits: 8, because the Message Type is an 8-bit message.

  1. data (up to 56 bits - 8 bytes): The following bytes refer to the Message data .

Next sections decribe each one of the possible messages with an example. The following examples include complete messages, so each beginning corresponds to Message Type.

MEX Status

MEX status message is composed as follows:

Type

Value

Bits

Description

cmd (t_version)

1

8

Version request / response

data

-

8

Version - Major

data

-

8

Version - Minor

data

-

8

Version - Revision

data (sysaddr)

-

8

Serial number - address 0

data (sysaddr)

-

8

Serial number - address 1

data

-

1

System Error bit (ID 7)

data (MEX status)

-

1

System power up bit error bit (ID 12)

data (MEX status)

-

1

PDI error bit (ID 9)

data (MEX status)

-

1

Memory Allocationbit (ID 8)

data (MEX status)

-

1

File system error bit (ID 6)

data (MEX status)

-

1

CAN A ERROR bit (ID 73)

data (MEX status)

-

1

CAN B ERROR bit (ID 74)

data (MEX status)

-

1

false

data (MEX status)

-

1

Arbiter enabled

data (MEX status)

-

1

Arbiter status

Arbitration

MEX Arbitration Status message is composed as follows:

  • Message 1: Sent when “Send status” is enabled

    Type

    Value

    Bits

    Description

    cmd (t_arbitration)

    0

    8

    Arbitration message

    Flag

    255 ([0xFF])

    8

    Status Flag

    CAP

    -

    7

    Active Autopilot (Current)

    data

    -

    1

    Arbitrating

    data

    -

    1

    AP0 Alive

    data

    -

    1

    AP1 Alive

    data

    -

    1

    AP2 Alive

    data

    -

    1

    AP3 Alive (External)

    data

    -

    1

    AP0 Ready

    data

    -

    1

    AP1 Ready

    data

    -

    1

    AP2 Ready

    data

    -

    1

    AP3 Ready (External)

    data (MEX status)

    -

    1

    System bit error (ID 7)

    data (MEX status)

    -

    1

    System power up bit error (ID 12)

    data (MEX status)

    -

    1

    PDI bit error (ID 9)

    data (MEX status)

    -

    1

    Memory Allocation bit (ID 8)

    data (MEX status)

    -

    1

    File system bit error (ID 6)

    data (MEX status)

    -

    1

    CAN A bit error (ID 73)

    data (MEX status)

    -

    1

    CAN B bit error (ID 74)

    data (MEX status)

    -

    1

    false

    data (MEX status)

    -

    1

    Arbiter enabled

    data (MEX status)

    -

    1

    Arbiter status

  • Message 2 (One for each Veronte Autopilot 1x): Sent when “Send score” is enabled

    Type

    Value

    Bits

    Description

    cmd (t_arbitration)

    0

    8

    Arbitration message

    data

    -

    8

    Autopilot ID [0, 3]

    data

    -

    32 (4 bytes )

    Autopilot score as Float

Command PWMs

Each PWM in MEX has to be associated to a Sub Id that indicates which CAN Bus message’s PWM is listening to.

That allows to control up to four PWMs using the same message if it is desired. Each message is composed by 4 PWMs maximum.

  • PWMs from 0 to 3 are sent in a message that includes 4 PWMs coded as 12-bit integers:

    Type

    Value

    Bits

    Description

    cmd (t_pwm_0_3_set)

    2

    8

    PWMs 0 to 3

    data (pwm0)

    -

    12

    PWM value for sub-id 0

    data (pwm1)

    -

    12

    PWM value for sub-id 1

    data (pwm2)

    -

    12

    PWM value for sub-id 2

    data (pwm3)

    -

    12

    PWM value for sub-id 3

  • PWMs from 4 to 7 are sent in a message that includes 4 PWMs coded as 12-bit integers:

    Type

    Value

    Bits

    Description

    cmd (t_pwm_4_7_set)

    3

    8

    PWMs 4 to 7

    data (pwm0)

    -

    12

    PWM value for sub-id 4

    data (pwm1)

    -

    12

    PWM value for sub-id 5

    data (pwm2)

    -

    12

    PWM value for sub-id 6

    data (pwm3)

    -

    12

    PWM value for sub-id 7

  • PWMs from 8 to 11 are sent in a message that includes 4 PWMs coded as 12-bit integers:

    Type

    Value

    Bits

    Description

    cmd (t_pwm_8_11_set)

    11

    8

    PWMs 8 to 11

    data (pwm0)

    -

    12

    PWM value for sub-id 8

    data (pwm1)

    -

    12

    PWM value for sub-id 9

    data (pwm2)

    -

    12

    PWM value for sub-id 10

    data (pwm3)

    -

    12

    PWM value for sub-id 11

  • PWMs from 12 to 15 are sent in a message that includes 4 PWMs coded as 12-bit integers:

    Type

    Value

    Bits

    Description

    cmd (t_pwm_12_15_set)

    12

    8

    PWMs 12 to 15

    data (pwm0)

    -

    12

    PWM value for sub-id 12

    data (pwm1)

    -

    12

    PWM value for sub-id 13

    data (pwm2)

    -

    12

    PWM value for sub-id 14

    data (pwm3)

    -

    12

    PWM value for sub-id 15

  • PWMs from 16 to 19 are sent in a message that includes 4 PWMs coded as 12-bit integers:

    Type

    Value

    Bits

    Description

    cmd (t_pwm_16_19_set)

    13

    8

    PWMs 16 to 19

    data (pwm0)

    -

    12

    PWM value for sub-id 16

    data (pwm1)

    -

    12

    PWM value for sub-id 17

    data (pwm2)

    -

    12

    PWM value for sub-id 18

    data (pwm3)

    -

    12

    PWM value for sub-id 19

Lift MCU telemetry

MEX to Autopilot 1x

The telemetry sent by MEX through CAN Bus is composed by:

  • Message 1:

    Type

    Value

    Bits

    Description

    cmd (t_mcu_tm1)

    18

    8

    Lift MCU telemetry data 1

    data

    -

    8

    Battery Serial Number [0]

    data

    -

    8

    Battery Serial Number [1]

    data

    -

    8

    Battery Temperature (as received from MCU)

    data

    -

    8

    Low Cell Voltage (as received from MCU)

    -

    4

    Reserved (Zeros)

    data (Status Bit)

    -

    1

    PWM receiving Ok

    data (Status Bit)

    -

    1

    CAN PWM receiving Ok

    data (Status Bit)

    -

    1

    CAN B receiving

    data (Status Bit)

    -

    1

    CAN A receiving

  • Message 2:

    Type

    Value

    Bytes

    Description

    cmd (t_mcu_tm2)

    19

    1

    Lift MCU telemetry data 2

    data

    -

    1

    Battery Serial Number [2]

    data

    -

    1

    Battery Serial Number [3]

    data

    -

    1

    Battery Serial Number [4]

    data

    -

    1

    Battery Serial Number [5]

    data

    -

    1

    Battery Serial Number [6]

    data

    -

    1

    Battery Serial Number [7]

Autopilot 1x to MEX

The telemetry sent from Autopilot 1x to MEX must be configured as follows:

Type

Value

Bytes

Description

cmd (t_mcu_cmd)

10

1

Lift MCU battery command

data

-

1

SUB-id A

data

-

1

LED Value A

data

-

1

SUB-id B

data

-

1

LED Value B

data

-

1

SUB-id C

data

-

1

LED Value C

Each MEX will use the SUB-id of the PWM associated to the “Scorpion Tribunus”/PWM ID to identify the value to be used.

Scorpion Tribunus ESC Telemetry (Lift)

The telemetry read from the Scorpion ESC is sent as:

Type

Value

Bytes

Description

cmd (t_esc_tm)

5

1

Scorpion Tribunus ESC telemetry data

data

-

1

Input voltage in range [0, 85]

data

-

1

Temperature in Celsius

data

-

1

Error Flags from the ESC

data

-

1

Current in Amps [0, 255]

data

-

1

Consumption in mAmps [0, 25500]

data

-

1

RPMs [0, 25500]

data

-

1

Throttle as percentage*2 [0, 200]

JetiTM ESC Telemetry

The telemetry read from Jeti-TM compatible ESCs is sent as:

Type

Value

Bytes

Description

cmd (t_esc_tm2)

6

1

Jeti ESC telemetry data

data

-

1

Throttle value [0, 200]

data

-

2

Current RPMs

data

-

10 bits

Input voltage in the range [0, 70] Volts

data

-

10 bits

Temperature in the range [0, 575] Kelvin

data

-

12 bits

Current in the range [0, 400.0] Amps

Jeti BEC Telemetry

The telemetry read from Jeti BEC will be sent in 2 different messages:

  • Message 1:

    Type

    Value

    Bits

    Description

    cmd (t_bec_tm1)

    7

    8

    Jeti BEC telemetry data 1

    data

    -

    16

    Device ID

    data

    -

    12

    Input voltage in the range [0, 70] Volts

    data

    -

    12

    Output voltage in the range [0, 70] Volts

    data

    -

    12

    Temperature in the range [0, 575] Kelvin

  • Message 2:

    Type

    Value

    Bits

    Description

    cmd (t_bec_tm2)

    8

    8

    Jeti BEC telemetry data 2

    data

    -

    16

    Device ID

    data

    -

    12

    Current in range [0, 100.0] Amps

Jeti Temperature Sensor Telemetry

The telemetry read from a Jeti Temperature sensor will be sent as:

Type

Value

Bits

Description

cmd (t_temp_tm)

9

8

Jeti Temperature sensor telemetry data

data

-

16

Device ID

data

-

12

Measured temperature 1 in the range [0, 750] Kelvin

data

-

12

Measured temperature 2 in the range [0, 750] Kelvin

Set Maintenance Mode Command

This command will configure the MEX in maintenance mode, setting its configuration in a way that communications can work over SCI-A, SCI-B or Serial-to-CAN configured as:

  • SCI-A and SCI-B: 115200 bauds, 8 data bits, 1 stop, no parity.

  • Serial to CAN:

    • TX Id: 1301

    • RX Id: 1301

The format of the command is:

Type

Value

Bytes

Description

cmd (t_cmd_maint)

16

1

Command to go to Maintenance Mode

Stick Selection Command

This command is used to enable or disable the MEX PPM reader. If address received matches the MEX’s one, MEX PPM reader will be enabled, otherwise it will be disabled.

The format of the command is:

Type

Value

Bytes

Description

cmd (t_stick_sel)

17

1

Jeti Temperature sensor telemetry data

data (sysaddr)

-

1

address 0

data (sysaddr)

-

1

address 1