Serial Interface

Introduction

Fenix Autopilot can be connected to a Laptop/PC via USB port. This provides access to all user functions available to calibrate compass and linear actuator. Also provides full capabilities to customize installation settings and pilot gain.

Requirements

• Serial Terminal shall be installed to Laptop/PC to communicate with Autopilot to use Serial Interface (eg. Arduino IDE, Putty)

• Checksum calculator

• $PMEC Message specification in this Guide.

Checksum

In order to generate $PEMC messages to be accepted by Fenix Autopilot, a checksum code shall be annexed after * symbol.

Serial I/F examples in this User Guide represent Checksum code as xx. To use these examples you should substitute xx by the calculated Checksum value.

Serial I/F Example: $PEMC,00*xx

Serial I/F Valid Sentence: $PEMC,00*37

In this link you will find an online Checksum calculator

NMEA MTK checksum calculator

Set messages: 04 and 06

To keep same value of a parameter while changing others, omit any value while keeping the commas in place.

To set Ki value while keeping Kp and Kd: $PEMC,06,,0.3,,,m*xx

Fenix V0.1 bug: Message 06, always include m, M or A deadband value or system will change to M.

$PEMC Message

Field	Value	Function	Additional Field	Sentence
1	00	Switch working mode from STAND BY to AUTO	N/A	$PEMC,00*37
1	01	Change Current Rudder	2: Change rate	$PEMC,01,r*68
1	02	Change CTS (Current Target Steering)	2: Change rate	$PEMC,02,i*70
1	03	Get Installation Parameters	2: Installation Parameters	$PEMC,03,2,45,5,S,2,-3.2,-32.9,10*xx
1	04	Set Installation Parameters	2: Installation Parameters	$PEMC,04,2,40,4,S,3,4.1,33.9,9*xx
1	05	Get PID gain (incl. sample time and deadband)	2: PID Gain	$PEMC,05,2,0.01,0.5,100,A*xx
1	06	Set PID gain (inc. sample time and deadband)	2: PID Gain	$PEMC,06,3,0.11,0.7,100,m*xx
1	07	Get Autopilot information	2: APinfo	$PEMC,07,S,12,35.60,30.02,2,-0.50*65
1	08	Request information	2: 'I' Request Installation Parameters (message $PEMC,03) 2: 'G' Request Gain (message $PEMC,05) 2: 'A' Request Autopilot info. (message $PEMC,07)	$PEMC,08,I*5A $PEMC,08,G*54 $PEMC,08,A*52
1	09	Enter/ Exit into IMU Calibration mode	N/A	$PEMC,09*3E
1	10	Enter/ Exit Feedback Calibration mode	N/A	$PEMC,10*36
1	11	Save values	2: 'I' Save Installation and current Feedback Parameters 2: 'G' Save current PID Gain parameters 2: 'C' Save current IMU Offsets 2: 'R' Restore Inst.Param, Feedback and PID Gain to hardcoded values	$PEMC,11,I*52 $PEMC,11,G*5C $PEMC,11,C*58 $PEMC,11,R*49
1	12	IMU Cal.Mode values	Cal.Mode values	$PEMC,12,

Additional Field: Change rate

Field	Value	Function	Additional Field
n	'i'	Increment Current by 1 Position Unit	N/A
n	'I'	Increment Current by 10 Position Unit	N/A
n	'r'	Reduce Current by 1 Position Unit	N/A
n	'R'	Reduce Current by 10 Position Uni	N/A

Additional Field: Installation Parameters

Field	Value	Function	Additional Field
n	Integer	Centered Tiller Position	N/A
n+1	Positive Int	Maximum rudder angle	N/A
n+2	Positive Int	Average Cruise Speed	N/A
n+3	'S'	Installation Side: Starboard	N/A
n+3	'P'	Installation Side: Portboard	N/A
n+4	Positive Int	Rudder Damping	N/A
n+5	Float	Magnetic Variation	N/A
n+6	Float	Heading Alignment	N/A
n+7	Positive Int	Off course alarm angle	N/A

Additional Field: PID Gain

Field	Value	Function	Additional Field
n	Float	Kp	N/A
n+1	Float	Ki	N/A
n+2	Float	Kd	N/A
n+3	unsigned long	Sample Time (mSec)	N/A
n+4	'm'	Deadband: Min	N/A
n+4	'M'	Deadband: Max	N/A
n+4	'A'	Deadband: Auto	N/A

Additional Field: APinfo

Field	Value	Function	Additional Field
n	'S'	STAND-BY Mode	N/A
n	'A'	AUTO Mode	N/A
n	'T'	TRACK Mode	N/A
n	'C'	Calibration Mode (IMU or Feedback)	N/A
n+1	Integer	Current Rudder	N/A
n+2	Float	Heading Magnetic (HDM) - Magnitude (M)	N/A
n+3	Float	Course To Steer (CTS) - Magnitude (M)	N/A
n+4	Positive int	Deadband value	N/A
n+5	Float	Trimming value	N/A

Additional Field: IMU Cal. values

Field	Value	Function	Additional Field
n	'-'	Calib. Not started	N/A
n	'O'	Calib. Ongoing	N/A
n	'R'	Recalibrated	N/A
n	'N'	Not calibrated	N/A
n	'C'	Check ongoing	N/A
n+1	1:OK/ 0:NOK	Sys status. Ony valid when Calib is ongoing	N/A
n+2	1:OK/ 0:NOK	Gyro status. Ony valid when Calib is ongoing	N/A
n+3	1:OK/ 0:NOK	Accel status. Ony valid when Calib is ongoing	N/A
n+4	1:OK/ 0:NOK	Magn status. Ony valid when Calib is ongoing	N/A
n+5	Int (0, 360)	X euler angle. Ony valid when Check is ongoing	N/A
n+6	Int (-180, 180)	Y euler angle. Ony valid when Check is ongoing	N/A
n+7	Int (0, 90)	Z euler angle. Ony valid when Check is ongoing	N/A

Additional Field: IMU Cal. values

Field	Value	Function	Additional Field
n	'-'	Calib. Not started	N/A
n

OpenCPN NMEA I/F

OpenCPN integrates GPS and plotter capabilities to provide user with all required means to define a route and send it to Fenix Autopilot. OpenCPN is required for Nav mode.

Fenix and OpenCPN implements NMEA I/F in both directions

Data sent by OpenCPN to Fenix Autopilot in ALL working modes from different sources:

• External Compass (only in External Compass mode):

Message: $HDM - Heading Magnetic

Features below are not available in V2.x

• Windvane and calculations

• GPS Fix

• Speed Log

Data sent by OpenCPN to Fenix Autopilot in NAV Mode:

Message: $APB - Autopilot Sentence "B"

• Route

  • Waypoint ID

  • Course To Steer to Next Waypoint (CTS) - Magnetic angle

  • Cross Track Error (XTE)

  • Arrival Circle Alarm

  • Perpendicular Circle Alarm

Feature available with limitations in V0.1: Only APB message decoded.

Data sent from Fenix Autopilot to OpenCPN in ALL working modes:

Internal compass (in Internal Compass Mode only):

Message: $HDM - Heading Magnetic

Message: $HDT - Heading True

Rudder position

Message: $RSA - Rudder Sensor Angle