PROHELION EV Driver Controls User Manual
- June 9, 2024
- PROHELION
Table of Contents
USER’S MANUAL
EV Driver Controls
PHLN86.002 ver 1
11 August 2021
INTRODUCTION
This document describes the interface, installation, and usage requirements
for the Prohelion EV Driver Controls product. It also provides information on
programming the device to implement custom functionality.
The EV Driver Controls provide an easy way to control a Prohelion WaveSculptor
motor controller. The driver controls come programmed from the factory
configured with sensible default values that will work in a plug-and-play
manner with a motor controller.
The EV Driver Controls provide analog and digital inputs, used to generate
commands to the motor controller. It also provides both analog and digital
outputs to drive dashboard gauges and error and status LEDs.
The microcontroller firmware for the device (written in ‘C’) is available on
the Prohelion website under an open-source BSD license, as are the hardware
schematics and component overlays.
PHYSICAL LAYOUT
The following illustration shows the connections and indicators on the front panel of the EV Driver Controls. A CAN bus connection, 12V in and out, and two status LEDs are present.
The rear panel contains a single DB37 connector, connecting all the analog and digital I/O connections required to drive a vehicle.
CAN BUS
3.1 CAN NETWORK TOPOLOGY
The CAN bus is structured as a linear network, with short stubs branching from
‘T’ connectors on the main bus backbone to each device. The CAN bus data lines
must be terminated at each end of the main bus with 120 ohm resistors between
the CAN-H and CAN-L signals.
In the range of Prohelion EV products, including the WaveSculptor 200, EV
Driver Controls, and
BMS Pack Master, the CAN connections are implemented with an ‘in’ and an ‘out’ connector, therefore placing the ‘T’ on the device, resulting in a very short fixed-length stub on the circuit board of each device. This is ideal from a signal integrity and network performance point of view.
The WaveSculptor motor controller uses the CAN bus to receive commands and
transmit telemetry, as well as to provide low-voltage DC power to operate the
controller electronics.
Therefore, a basic system consists of three major components:
-
WaveSculptor motor controller
-
Driver controls interface to pedals, switches & gauges
-
Power supply (nominally 12V DC) to operate the system
Other components can also be added to the network. Items typically found in an electric vehicle would include: -
LCD and other driver information displays
-
Battery management system
-
Multiple motor controllers
-
Datalogging
3.2 CAN WIRING
The CAN data lines (CAN-H and CAN-L) must be implemented with twisted-pair
wire for proper data integrity. The wire should have a characteristic
impedance of 120 ohms. Power should also be provided along the CAN cable,
ideally with another twisted pair to minimise noise pickup. An overall shield
can also be advantageous.
From a performance perspective, the optimal choice of cable is 7mm Devicenet
CANbus ‘thin’ cable, with 24AWG (data) + 22AWG (power) twisted pairs and a
braided shield. Using this cable will result in a robust installation.
However, it is not cheap, and using it for a large network with many devices
will quickly add up to a significant cost.
For those on a budget, standard CAT5 network cabling (which has an impedance
of 100 ohms) can be used, but may become unreliable in longer networks or in
the presence of electrical noise from DC/DC converters and other electrical
devices in the system – use this type of cable at your own risk.
3.3 CAN CONNECTOR
The connector used on the EV Driver Controls and other Prohelion devices is a
6-way 3mm pitch Molex MicroFit connector. The pinout is shown below, as viewed
from the wire side – as you would look at it while inserting crimps. The
colours shown match those in the standard DeviceNet CAN cabling pairs.
3.4 CAN SHIELDING
If the recommended braided shield is used in the cable, then terminate it to
the SHIELD pin (lower-left corner on the connector) on both CAN IN and CAN OUT
connectors on each device. On one device only in the network, instead of using
the SHIELD pin, terminate the shield to the SHIELD GROUND pin (upper-left
corner on the connector) on both CAN IN and CAN OUT connectors, to ground the
shield for the entire network at this single point. The usual place to do this
is where power is fed into the network, typically at Prohelion ‘s EV Driver
Controls product.
3.5 CAN TERMINATION
To implement the required 120 Ohm termination resistor at each end of the CAN
bus, plug a connector into the unused CAN connector on the last device at each
end of the network with a resistor crimped into the appropriate locations.
3.6 COMMUNICATIONS
The CAN standard does not specify high-level message protocols. Prohelion
devices use a custom protocol, outlined in the communication specification
document for each device. By default, each device operates at 500
kbits/second, one step below the maximum possible data rate of 1 Mbit/second,
and comes programmed from the factory with a CAN base address that will allow
it to work without problems with other Prohelion devices. Currently, modifying
the driver controls data rate or CAN base address requires reprogramming the
microcontroller, although hardware support is provided to allow updates over
the CAN bus in the future. The WaveSculptor motor controller expects regular
messages from the driver controls device. If a message is not received within
a set timeout period then the controller will change to a safe mode and will
stop driving the motor. This protects against faults where either a connector
is loose or broken, the cable has been damaged, or the driver controls have
failed.
3.7 POWER SUPPLY
The EV Driver Controls provides a means to connect power from the 12V car
battery into the CAN bus, to power other devices on the network. The default
software switches power to the CAN bus based on the state of the ignition key
– the CAN bus will be powered if the key is in either the Accessories or the
Run position.
3.8 SYSTEM EXPANSION
Prohelion can provide a CAN bus LCD display capable of showing up to four
different telemetry values (one at a time) on a 3.5 digit sunlight-readable
screen. Multiple displays can be used if desired.
3.9 MULTIPLE MOTORS
Multiple motors/controllers are accommodated easily with the CAN bus system.
All that is required is for each WaveSculptor controller to be programmed to
receive messages from the same driver controls base address, and then to run
the vehicle in current-control mode (the default setup). Each motor will now
operate at the same current, thus giving automatic wheel speed differences for
cornering, with the system acting as an electronic differential.
12V INPUT & OUTPUT
4.1 POWER SUPPLY
The Driver Controls requires a 12V power connection to the spade terminals on
the front panel. This connection should be capable of supplying enough current
to run all devices on the CAN bus, plus the expected current draw of the brake
and reversing lights (if connected). It should be fused externally to the
driver controls.
This power can be from an ‘always on’ connection, however the driver controls
draws around 30mA continuously, so will drain your accessory battery if your
DC/DC converter from the high voltage traction pack does not operate
continuously. This current draw will be lower in the future, however sleep
mode functions are not implemented in the default software at this point.
Supplying the driver controls from a relay activated by the ‘Run’ position of
the ignition key is a good compromise.
Supplying the driver controls from the ‘Accessories’ position of the ignition
key is not recommended as this power is usually cut when the key is moved to
the start position.
4.2 BULB DRIVE OUTPUTS
The driver controls has two 12V 3A outputs, and the default software is
suitable for connecting these two outputs to your brake lights and your
reversing lights.
This is so that the brake lights can activate if regenerative braking is used,
and the reversing lights can be activated if you are using a fixed ratio
gearbox and are performing vehicle reversing by changing the motor rotation
direction.
If you a re not using regen braking then you can leave the brake output from
the driver controlsdisconnected, and leave the vehicle wiring untouched.
If you are using a conventional gearbox to perform reversing, then you can
leave the reversing output from the driver controls disconnected, and leave
the vehicle wiring untouched.
VEHICLE CONTROL CONNECTIONS
The vehicle control connector is a female DB37 socket. The following illustration shows the pinout as viewed when looking into the driver controls, the same view you have when soldering or inserting crimps into the rear of a mating connector housing.
All ground pins on the connector are identical, and connected together internally to the driver controls. They are provided separately on the connector to simplify wiring, as a ground can be run out from the driver controls along with the bundle of other wires going to each input or output device.
5.1 ANALOG INPUTS
The driver controls provide three analog inputs. These are suitable for
connecting to a potentiometer (1k to 10k linear recommended), with the driver
controls supplying a stable 5V supply, capable of up to 75mA shared between
all three outputs. They are also suitable for connection to a voltage output
device such as a hall-effect ‘drive by wire’ pedal assembly, as long as it is
capable of operating from 5V and has outputs that do not go below ground or
above 5V. Most pedals meet these requirements. The default software uses the
Analog A channel as the motor current input, suitable for connection to your
accelerator (gas) pedal. It has a small dead-band at either end of the pedal
travel, but basically maps 0 to 100% throttle to the full range of
potentiometer movement. Analog B and Analog C are planned to be used for the
2nd cross-check output from a hall pedal, and the regenerative braking
strength slider control, respectively. However neither is currently
implemented in the default software.
5.2 DIGITAL INPUTS
Multiple digital switch or voltage inputs are provided. Each input accepts a
voltage between ground and the 12V supplied to the driver controls. Inputs
have a wide hysteresis band to provide noise immunity, and a 10k pull-up
resistor to avoid floating inputs. Inputs can be connected to a signal that
will either be 12V or ground, such as the ignition switch position outputs.
Inputs can also be connected to a toggle or pushbutton switch to ground, with
the internal pullup resistor providing the alternative logic level. Inputs are
configured in four groups, but they are all identical in hardware and can be
remapped as desired by modifying the device software.
The default firmware is configured with the input polarity suitable for the
following inputs:
- Ignition Accessories, Run, and Start positions (voltages: 12V = active)
- Brake Status (voltage: 12V = brakes on)
- Fuel Door switch (switch to ground: closed to drive, open to charge)
- Gear selection (switches to ground: closed to select specific mode)
The default software provides power to the CAN bus if the ignition switch
Accessories or Run inputs are active.
The default software will only issue commands to the motor controller if the
ignition switch Run input is active, and the fuel door is closed.
The default software will send 0% torque commands to the motor controller if
the brake switch is active.
The default software will drive in the forwards direction if Gear Switch 1 or
2 is selected, will switch to Neutral if Gear Switch 3 is selected, and will
drive in reverse if Gear Switch 4 is selected.
Do not select multiple gears simultaneously.
5.3 ANALOG OUTPUTS
Four analog outputs are provided to drive dashboard gauges or other devices in
the vehicle. All hardware is functionally identical, and capable of providing
either a 0-12V pulse train output, or a ‘variable resistance’ to ground. This
allows driving either a tachometer type gauge, or a fuel type gauge.
The default software drives Gauge outputs 1 and 2 as pulse outputs, with Gauge
1 showing engine RPM, and Gauge 2 showing system power. The default software
drives Gauge outputs 3 and 4 as resistance outputs, with Gauge 3 showing
battery voltage, and Gauge 4 showing motor controller temperature.
5.4 DIGITAL OUTPUTS
Eight digital outputs are provided, each capable of driving to either Ground
or 12V, and capable of up to 100mA per output. These outputs are not protected
against overcurrent, and are designed to drive current-limited LED loads or
small relays. Take care to avoid overloading these outputs, and make sure to
use a diode clamp across the coil if driving a relay. If used, each output
should be connected through a LED and a current-limiting resistor to Ground.
Select the resistor value to set the LED current to the brightness required in
your situation. For a typical LED, a 560 Ohm resistor will give approximately
20mA LED current, giving high brightness from a standard 3mm or 5mm LED.
The default software shows the currently selected gear mode by illuminating
one of the Gear LED 1-4 outputs. The Gear LED backlight is illuminated if
either the ignition Accessories or Run positions are active.
The Fault LED outputs are unused by the default software.
BASIC CONNECTION DIAGRAM
The following schematic shows the simplest possible connection, when using the default software.
SOFTWARE PROGRAMMING
7.1 OVERVIEW
The driver controls are based around a Texas Instruments (TI) MSP430 16-bit
embedded lowpower microcontroller, operating from a 16 MHz clock as default.
CAN bus support is provided via a Microchip MCP2515 CAN controller and TI
SN65HVD234 CAN transceiver. The driver controls are not isolated from the CAN
bus.
7.2 SCHEMATICS & SOURCE CODE
Schematics and PCB component position overlays in PDF format are available for
download on the Prohelion website. A zip file is also provided containing the
default source code for the microcontroller, written in ‘C’ and available
under a BSD open-source license. Please refer to these references if
developing custom firmware for the driver controls.
7.3 TOOLCHAIN
The example default code provided is configured to work with the freely-
available open-source MSP430 GCC toolchain, which provides a command-line
driven compiler, binutils, download, and real-time debug capability through a
JTAG header present on the driver controls PCB. The debug functionality
requires purchase of a USB programmer from Texas Instruments. Please refer to
the README file with the source code for download and installation
instructions.
7.4 CODE DOWNLOAD
The EV Driver Controls contains a facility to load new software into the
device via the CAN bus. This works in conjunction with our CAN-Ethernet
bridge. The bootloader utility is available on the Prohelion website. Using
this method of programming means that a debugger is not possible, but it works
immediately and does not require the purchase of additional hardware.
REVISION RECORD
| REV | DATE | CHANGE |
|---|---|---|
| 1 | 11-Aug-21 | Document creation (AJP) |
©2021 Prohelion Pty Ltd
Brisbane, Australia
http://www.prohelion.com