Throttle

The throttle controls the motor and is operated by the pilot during sailing. It controls the duty cycle of the motor via the CAN bus using the standard VESC message format.

Usage

Throttle shown in the inactive (green led) neutral position

To use the throttle to control the motor the green illuminated arm-button will have to be pressed for a few seconds, however some conditions need to be met to ensure a safe start of the motor.

1. The dead-man cord needs to be applied to the bottom of the throttle body, should snap in place magnetically
2. The throttle lever Should be in its neutral position, pointing straight up with a noticeable tactile bump
3. The CAN bus need to be actively acknowledging packets, which means other devices need to be active on the bus
4. No other error should have occurred inside the electronics

If one of these conditions is not met, the throttle will beep the number of times indicated above.

Programming Throttle Position

The throttle position is read out by a magnet attached tot the throttle lever, because the orientation of this magnet is not know in the firmware, this position can be programmed into the EEPROM. To enter programming mode hold down the arm button during power-on. A four beep descending tone should be played, and the LED should do a double blink in red continuously. To program the throttle push lever as far forward as possible and press the button, a single beep be heard. Repeat this twice with the lever in the center and finally with the lever all the way backwards. After three beeps the throttle is reprogrammed and normal operation is resumed.

If no programming is desired leave the lever alone for 10 seconds and the lever will reboot into normal mode.

Setting the Control Mode over CAN

The Throttle controls the VESC motodriver at 10Hz messaging rate with the default CAN format implemented inside the VESC. More info on the format. The throttle supports four modes:

Different control modes of the throttle

Control Mode	Configuration Byte Value	Unit	Additional data required
Duty Cycle	0x01	Percentage	None lever in the maximum forward position is 100%
Filtered Duty Cycle	0x02	Percentage	None lever in the maximum forward position is 100%
Current Control	0x03	100mA	Specify the max current for forward and backwards in two int16_t's
RPM Control	0x04	RPM	Specify the rpm for forward and backwards in two int16_t's

These modes can be send to the throttle when the throttle is off. If the throttle is on the configuration will be ignored. A sound will play when a message is received. The message has to be send to the Throttle address 0x1337, same as the reboot command. the format is as follows:

Can Message for Setting the control mode

Byte 0	Byte 1	Byte 2	Byte 3	Byte 4	Byte 5
0xAA	Control type	MSB int16_t	LSB int16_t	MSB int16_t	LSB int16_t
Hardcoded command	See Table Above	Max value for lever completely forward		Same but for backward (Positive for reverse)

CAN Diagnostics messages

The throttle also send out messages to help debugging every 200 ms. It is send on address 0x337 and has the following format:

Can Message for Diagnostic Purposes

Byte 0	Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7
MSB int16_t	LSB int16_t	MSB int16_t	LSB int16_t	MSB int16_t	LSB int16_t	uint8_t	Error status
Filtered lever position, from +512 to -512		Raw position reported by the magnetic encoder		Raw data from the deadmanswitch ADC		Gain that is required to readout the lever position	Enum of current error state. 0x00 is good

If any of the error status bits are set, the throttle is set into IDLE mode and will shut off the motor. The following table shows what the bitfield represents:

Different control modes of the throttle

Bit	Enum Name	Explanation
0 to 2	twiError	See next table for possible values
3	noLimitsLoaded	Reading of EEPROM for throttle limits failed
4	gainClipping	The Magnetic encoder detected no good magnetic field present
5	gainInvalid	The gain value read from the magnetic encoder is beyond the range specified in software
6	deadmanMissing	The hall sensor of the deadman-switch doesn't detect a strong enough magnet
7	impeadanceHigh	The impeadance of the deadman signal is too high, indicating a bad connection

TWI error states

Value	Error name	Error Description
0	TWI_ERROR_NoError	Indicates that the command completed successfully.
1	TWI_ERROR_BusFault	A TWI bus fault occurred while attempting to capture the bus.
2	TWI_ERROR_BusCaptureTimeout	A timeout occurred whilst waiting for the bus to be ready.
3	TWI_ERROR_SlaveResponseTimeout	No ACK received at the nominated slave address within the timeout period.
4	TWI_ERROR_SlaveNotReady	Slave NAKed the TWI bus START condition.
5	TWI_ERROR_SlaveNAK	Slave NAKed whilst attempting to send data to the device.