Sequential LED Tail Lights For Ford Mustang

Size: px

Start display at page:

Download "Sequential LED Tail Lights For Ford Mustang"

Raymond Weaver
5 years ago
Views:

1 Sequential LED Tail Lights For Ford Mustang Project Description Brandon Delgado Western Washington University EET Fall 2013 Page 1 of 14

2 I. FUNCTIONAL DESCRIPTION: a. Project Summary The Proposed project is the design and creation of a microprocessor controlled CAN connected, sequential LED tail light system specifically for early model Ford Mustangs. The unit will be able to detect user input such as left/right turn indicator activation, running light activation, and brake system operation. LEDs will be used in the tail light housing. Multiple light sources will allow for an aesthetically pleasing and noticeable display al erting other drivers to the user s intentions. Microcontrollers will control the timing of the LEDs and the CAN network will transmit data from one controller to the other. b. Description There will be three main components in the system, user input detection, signal light controller, and the lighted signals themselves (Figure 1). The user input detection will rely on a microcontroller (MCU) that will detect activation of the turn signal switch including the direction of the switch throw. This will be handled by routing each of the two 12V leads of the turn signal switch into ports of the MCU that can detect high low states. This will be the same method used to detect when the user activates the running lights. However, there wil l be provisions for a pressure sensitive device connected through and A/D converter to activate the brake lights. This will allow the MCU to detect when the driver performs a panic stop and will alert the signal controller to flash the brake lights quickly to ale rt other drivers of a rapid stop (Figure 2). The lights should flash at 4 Hz as required by UN regulation 48 for emergency stop signals. All communications to the signal controller will be made over the CAN. The signal controller will also use an MCU to process the signal states sent from the user input detection controller. The signal controller will then use pulse width modulation (PWM) to control the signal board. The signal controller will also handle the timing and direction of the LEDs. For running lights the LEDs will constantly run at lower than 100% power producing no more than 25 candela, to illuminate the rear of the vehicle (Figure 2). For a turn indicator the lights will be flashed in sequence from the inside of the light housing to the outside at a higher power than that of the running light no more than 420 candela so that other drivers will be able to distinguish the difference (figure 2). For brake lights all LEDs will run at higher power, again, no more than 420 candela to alert others to a stop. If a panic stop signal is received then all LEDs will flash at 4 Hz as defined by UN emergency stop signal (ESS) regulations; to gain the attention of other drivers quickly. The signal board will be of my own design and use surface mount LEDs. The LEDs will be arranged so that they are visible in all three panels of the tail lights and will operate in individual banks. They will be powered off of the vehicles 12v rail and operated via PWM signal from the signal controller. Additional features that could be included are extra modules that operate on the CAN buss. Such as an engine monitoring board with data logging. Also, the whole car could be converted to use the CAN buss so that all electronics are controlled via MCU, including the heater fan which could be controlled using PWM. Of course the light boards will need to fit within the OEM housings. The maximum dimensions must be no more than 6 inches by 8.5 inches.(figure 2) The other units must only fit within the under dash area of the vehicle which is rather large though I intend to keep the unit confined to a 5x3 inch area which should fit nicely beside the fuse box. Page 2 of 14

3 +12v Figure 1 Turn Indicator Switch +5v Headlight Switch User Input Detection MCU +12v Brake Pedal Switch Signal Control MCU Light board Page 3 of 14

4 Figure 2 All off Running lights Brake Lights Panic Brake Lights (flashing) Turn indicator sequence Page 4 of 14

5 Figure 3 14k RAM 512k Flash EEPROM ATD0 AN0 Brake Pedal pressure +12v Low Voltage Headlight switch +12v +12v 5 V regulator Reset 9S12DP512 GPIO PTT0 PTT1 PTT2 MCU over voltage protection Turn indicator R Turn indicator L XTAL CAN2 PM6 CAN Transceiver 16MHz Crystal Page 5 of 14

6 Figure 4 2k RAM Low Voltage 32k Flash EEPROM GPIO PTT0 Orientation Switch 9S12C32 Reset PWM PWM0 PWM1 PWM2 PWM3 +12v LED Power Driver V regulator LED Power Driver 3 LED Banks 0-2 LED running Lights 8MHz Crystal XTAL CAN0 PM0 CAN Transciever Page 6 of 14

7 c. Feature List: i. User control via OEM switches ii. CAN communication between control module and light module iii. PWM LED control iv. Separate running, turn indication, and breaking modes Possible Features: i. Panic breaking indication ii. Headlamp control iii. Front turn indicator retrofit iv. Engine diagnostics and data logging d. Detailed Functional Description: Both the user input controller and the light controller will use the 9s12 famil y microcontroller. The input controller will be a 9S12DP512 while the light controller will be a much smaller MC9S12C32. These seem to be the most appropriate units. They were designed for automotive applications in mind. Additional benefits include developer familiarity and the inclusion of MSCAN module. Communications will utilize MSCAN on the CAN 2.0 network. Early research suggest the ability to use a single wire protocol allowing for the use of the original wiring. Communication will be over the driver side break light line while power will be sourced from the passenger side break light wire. As seen in Figure 3 there in the cab of the vehicle controlling the user input will be the 9S12DP512. Connected to it; a hydraulic pressure transducer, a headlight switch and the turn indicator. The 9S12DP512 will handle all of the input from the driver by applying a system that will check the status of each port. This will be stored on the available 512k EEPROM and will utilize the available 14k ram. Also, used be the GPIO, AtoD convertor and the CAN protocol via a CAN transceiver. The brake pedal pressure transducer should use standard 1\4 inch NPT fittings or at least be adaptable and should be optimized for use in a hydraulic circuit. Also, it should operate in a range from 9-15 volts. This will allow operation of the tail lights even when the vehicle is powered off. It will monitor the pressure in the brake circuit and report back to the MCU no other function is required of this unit. The headlight switch is the standard switch installed in the vehicle it has three positions. Off, parking lamps, and headlights. In the off position it 0V will appear on the input to the MCU over voltage protection which in turn will register off on the GPIO port assigned it. In both parking lamp and headlight mode the switch will apply 12V to the MCU over voltage protection circuit which will register as on at the GPIO port assigned it. The turn signal indicator is a single pole center off switch which when activated will apply 12V on one of two channels which will feed into protection circuitry and then Page 7 of 14

8 into their own individual GPIO ports to alert the Microcontroller that directional signal is required. Figure 4 deals with the control of the actual signaling lights. This is accompl ished by using a 9S12C32 chip. The Microcontroller will use a simple task to check for incoming CAN messages via the CAN transceiver described above. It will then use the PWM ports to drive the required combination of LEDs. There will also be an orientation switch that the controller will use to determine which side of the vehicle it is installed. This, allows the two board to be identical keeping the costs low. The 9S12C32 is also a 5V unit and will require a regulator to protect it from the voltage range of 9-15V. LED power drivers 0-2 will be functionally identical driving a bank of high power LEDs. This can be accomplished with a constant current or constant voltage design. The driver will however require a PWM enable function and both buck and boost characteristics so that the lights will operate regardless of the ignition status. LED power driver 3 will be used to drive the low power LEDs that are used for the running lights. This should be a constant current device with boost characteristics. There a large bank of LEDs however they will use much less current than the high power LEDs. Also, the low power LEDs will also use PWM control. This driver could also use multiplexing to save power. The orientation switch needs be no more than a jumper that will be set to driver or passenger during installation that the MCU will reference so it knows which bank of LEDs is the inboard bank. With this in place it is possible to use the same design for both sides of the vehicle. e. Software Requirements: The primary coding language will used will be ANSI C. Code conventions will be strictly followed. µc/os will be used on the 9S12DP512 as a preemptive kernel which will handle the required tasks and run them at an interval quick enough to keep up with the inputs from the driver; about 5ms. Tasks include, Switch polling, brake pedal polling, and a CAN task. The switch polling will simply check GPIO pins for a high level indicating the activation of either the head light switch or the turn indicator. This information will be sent to the CAN task, which will then send instructions over the CAN network if required. A high priority check of the AtD convertor will be used for the brake pedal as it is a critical indicator. If the brake pedal is depressed then the CAN task will alert the light controller immediately. Also, time permitting, there will be a task to sample the analog output of a hydraulic pressure transducer when the brake pedal is depressed. This will then determine if the panic braking warning need be sent. The preemptive kernel will increase the required amount of ram, however there is 14k available and the program is likely to be less than 5K. The light controller will use a time slice kernel in order to save on required memory as only 2k of RAM is available. Function of the light controller is to receive instructions over the CAN network and activate the corresponding LEDs. This will be done by applying a PWM signal to one of the PWM port pins. Also upon initialization the micro controller will check a switch mounted on the light board to determine which side of the vehicle it is located on. When not actively illuminating the rear lights the board will go into pseudo-stop mode and monitor the CAN network for communications. Page 8 of 14

f. User Interface: The user interface will remain stock as the vehicle came from the factory. This includes the Headlight switch, the turn indicator lever, and the brake pedal.

9 f. User Interface: The user interface will remain stock as the vehicle came from the factory. This includes the Headlight switch, the turn indicator lever, and the brake pedal. Figure 5 The round switch circled in red in figure 5 is the headlight switch. It is a dual triple throw single dual pole switch. All the way in is off, out one throw is parking lamps(including tail running lights), out two throws engages the headlights as well as the parking lamps. In this project only the pole associated with the parking lamps will be checked. If the driver pull the switch one or two clicks the running lamps will activate in identical function. The lever marked by the yellow rectangle in Fig. 5 above is the turn signal indicator lever. It is a single pole center off double throw switch. It is pressed towards the roof to indicate a right hand turn, and towards the floor to indicate a left hand turn. It automatically returns to the center off position after a turn of the wheel in the indicated direction. Each of the two throws has its own channel that will let the MCU know which direction the switch has been thrown. The brake pedal marked by the green rounded triangle is a lever with the fulcrum attached to the firewall. There is plunger just below the fulcrum that applies horizontal force to the hydraulic reservoir. This in turn creates pressure in the break system. A pressure which forces the brake shoes into the brake drums. The pressure will be monitored be the MCU. Thresholds for no pressure, normal breaki ng, and panic breaking will be established by monitoring brake line pressure in each situation. g. Communication Protocol: The CAN network will be used and will follow the SAE J1939 standard. There are 8 parts in a CAN transmission, start of frame, CAN-ID, Remote Transmission Request, Control, Data field, Cyclic Redundancy Check, Acknowledgement, and End of Frame. The CAN-ID uses a 29bit identifier which is then broken up into five sections. The first three bits sets priority with 0 being highest. A reserved bit and a data page bit used to extend max number of pages. Then the PDU format is 8 bits and is used to determine if the message is meant for the whole network or just one device. Then the last 8 bits are the destination address of the device specific message. The data field is where the message is transmitted in the case of this project, brake, left, right, running, or panic stop. According to SAE specifications the identifier is vehicle specific. If the Ford Motor Company is unwilling to share the current identifiers an arbitrary identifier will be assigned during development. Page 9 of 14

10 h. Sustainability: This project will use considerably much less power than the OEM 50watt bulbs. Also it will use a low power state to further increase fuel economy by reducing the draw on the engine. Waste must be taken into account by properly simulating the design before attempting to assemble a PCB in order to reduce the amount of unusable components. II. III. Standards: I will use the SAE J1939 CAN standard which will guide CAN integration into a highway legal vehicle. SAE J585 FEB2008 Tail Lamps (Rear Position Lamps) for Use on Motor Vehicles Less than 2032 mm in Overall Width SAE J586 JUL2007 Stop Lamps for Use on Motor Vehicles Less than 2032 mm in Overall Width SAE J588 MAY2006 Turn Signal Lamps for Use on Motor Vehicles Less than 9.1 m in Overall Length (SAE J1373 was removed as it concerned corning lamps which are not turn signals but are white lights used to illuminate the direction which the vehicle is turning. This does not fall in the scope of this project.) Development Plan: a. Development Tasks: First priority will be to design and build the light boards. This includes selection and testing of LEDs, circuit design and simulation, and finally construction. This should be complete by the end of winter quarter so that spring quarter may be dedicated to software design. Potentially development will be delayed if the PCB manufacturer is backlogged with orders, this is the component with the most lead time, up to 2 weeks. Page 10 of 14

11 WEEK Task 47 Test LEDs that have arrived 48 Begin schematic design and simulation 49 continue design and simulation 50 finalize design and simulation 51 order PCB prototype 1 52 Christmas break 1 study SAE CAN standards 2 Assemble PCB and test 3 Test PCB 4 Test PCB 5 Revise PCB Layout and simulate 6 order PCB prototype 2 7 write code to test light functions 8 Assemble PCB and test 9 Finalize PCB design and order final revision 10 begin writing CAN communication code 11 CAN communication code 12 CAN communication code 13 Software Review 14 Final software revisions 15 In vehicle testing 16 In vehicle testing 17 In vehicle testing 18 Hardware design review 19 Software Presentation 20 buffer 21 Code reviews 22 DEMO 23 Turn in final project b. Development Hardware and Software: Hardware used in development will include desktop power supplies, Oscilloscopes, and bread boards for circuit testing. Software will include DX designer for PCB layout and schematic capture. Also Code Warrior will be used in the development of software. Page 11 of 14

12 c. Demonstration: The product will be demonstrated using two pieces of plywood. One sheet will have switches that mimic the vehicle switches one dual throw dual pole switch for the turn indicators, a single pull single throw for the headlights, and a pot to mimic the pressure transducer. If time allows a working brake system could be included with the demo. The second sheet will have an OEM tail light and the LED sequential tail light mounted side by side so that new versus old can be directly compared side by side. Users will be able to mimic all functionalities of the driver. IV. Electrical Specifications: a. Project Specifications: The system will need to monitor and respond to inputs within 25ms so that there is no perceptible delay. If there is any delay it could pose a serious safety issue especially with the operation of the brake light system, this will require both a laye r of redundancy and high speed processing. Input voltage will be 9-15V this range is due to battery. If the car is not running while systems are using power then the battery will discharge. While the vehicle is running the alternator applies 14.3 volts across the system. 9V was chosen as minimum input voltage because that is the minimum voltage required to start the car. If the voltage falls below 9v the battery will need to be charged. The tail lights are limited to 14 amps (fused) this should be more than enough current to drive the LEDs. Luminous output as defined in SAE J585, J586, and J588 is restricted to 25cd for the running lights, and 420cd for the turn indicator and stop lamps. (J587 specifies characteristics for the License plate lamp and is not within the scope of this project.) Input voltage for the 9S12 is 5V so voltage regulation is necessary to maintain operation in all vehicle states. Page 12 of 14

13 b. Power Requirements: Light control board Part Quantitiy Voltage Current Max Power Price 9S12C LED power Driver HP LED power Driver LP High Power LED Running Led Pressure transducer Resistor Jumper PCB User interface Part Quantitiy Voltage Current Power Price 9S12DP Pressure transducer Resistor PCB c. Special Environment Requirements: As this is an automotive project, components will need to withstand both high and low temperatures from degrees C as specified by commercial grade temperature ranges. Also, vibration must be taken into account because the vehicle will travel at speed on uneven roadways, as well as just the vibrations of the engine could pose an issue. Rubber dampers will be used to isolate the components. d. PCB Size limits: The control module will need to fit in a 5X3X2 inch space while the light boards must fit in a 6x8.5x3 inch space. Page 13 of 14

14 V. Preliminary Parts List: Light control board part Quantitiy Voltage Current Max Power Price 9S12C LED power Driver HP LED power Driver LP High Power LED Running Led Pressure transducer Resistor Jumper PCB User interface Part Quantitiy Voltage Current Power Price 9S12DP Pressure transducer Resistor PCB Figure 5 referenced from Davit Toth; Restoring A 1965 Ford Mustang Metal Dash, And Installing a Ford Dash Pad. END OF DOCUMENT Page 14 of 14

Sequential LED Tail Lights For Ford Mustang

Sequential LED Tail Lights For Ford Mustang Project Proposal Brandon Delgado Western Washington University EET Fall 2013 Page 1 of 5 I. Project Summary The Proposed project is the design and creation of