Summary of Electrical Subsystem
This article details an automatic shift control system for an ATV, integrating manual inputs with advanced electrical subsystems. The design utilizes an MSP430F1610 microcontroller to process data from throttle, RPM, and transmission sensors, managing solenoid drivers and spark cut outputs. Key components include a 3.6V power supply, voltage dividers for signal conditioning, and hardware debouncing circuits, all aimed at optimizing performance while maintaining low power consumption.Parts used in the Automatic Shift Control System:
- MSP430F1610 16-bit microcontroller unit
- 500mA, 3.6V LDO linear regulator (MIC5219)
- Throttle position sensor
- Shift pushbuttons
- Mode selector switch
- RPM sensor
- Transmission switch
- Solenoid drivers for upshift/downshift
- Spark cut driver
- Display indicators array
The electrical design was driven by the complexity required by the mechanical system. The system takes in rider input in the form of a throttle position sensor, shift pushbuttons, and mode selector. It also takes in other input that the rider doesn't have direct control over; an RPM sensor and the transmission switch for detecting gear position.
Outputs consist of drivers for the solenoid (up and down) and the spark cut output.
System Level Schematic
The above diagram shows the system level electrical connections from the control board to the ATV. These connections were developed from the designed controller to meet the customer needs.
Microcontroller Schematic
- The Processor
The MSP430 family of processors was reused from the previous year.
- 16-bit microcontroller unit, MSP430F1610
- C compilers available for easier and faster code development than assembly.
- Enough inputs/outputs to cover all required sensors/inputs and outputs required by the design.
- Low voltage @ 3.6V, low current @ <25mA. Low-power requirements to ease energy budget on the ATV.
- 8 MHz external clock for heavy math calculations and fast ADC samplings.
- 16 interrupt vectors to handle asynchronous inputs/outputs.
- On-board peripherals such as ADC (for TPS), 2 timers/CCPs (shift timing), hardware mult. (math calcs)
- Board Power Supply
- 500mA, 3.6V LDO linear regulator (MIC5219) step-down from 12V ATV battery
- On/off control by ignition switch input.
- Inputs
- Throttle position sensor from ATV ranges from 0-12V, so a voltage divider moves the range of voltage into the MSP430 to 0-3.6V. Sampled by ADC.
- Pushbutton switches from handlebars are hardware debounced using resistor-capacitor network.
- Mode switch is divided down from 12V by voltage divider. Common on switch is connected to 12V supply externally.
- Transmission switch senses when ATV is in Neutral or Reverse or neither. Also is divided down from 12V input.
- RPM input blocks all noise below 5.1V by zener diode. Typical RPM input voltage level is an 8V square wave.
- Outputs
- Solenoid low-side (connects to ground) drivers for upshift/downshift. Capable of >40A peak.
- Spark cut low-side driver connecting to CDI module.
- Indicators of display are driven by low-side array.
1, 2 outputs are switched on and off by timerB internal to MSP430.
Read More: Electrical_Subsystem
Quick Solutions to Questions related to Automatic Shift Control System:
- How does the system handle rider input?
The system accepts rider input via a throttle position sensor, shift pushbuttons, and a mode selector. - What processor is used in the design?
The design reuses the 16-bit MSP430F1610 microcontroller from the previous year. - Why was the MSP430 selected for this project?
It offers C compilers for faster development, sufficient I/O, low voltage operation, and on-board peripherals like ADC and timers. - How is the 12V battery voltage converted for the controller?
A 500mA, 3.6V LDO linear regulator steps down the 12V ATV battery voltage to 3.6V. - How are the pushbutton signals processed?
Pushbutton switches are hardware debounced using a resistor-capacitor network. - How is the RPM input signal conditioned?
An RPM input block uses a zener diode to filter noise below 5.1V from the typical 8V square wave. - What type of drivers are used for the solenoids?
Low-side drivers connect to ground and are capable of handling over 40A peak current. - How are the display indicators controlled?
Indicators are driven by a low-side array switched on and off by TimerB internal to the MSP430.
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Ibrar Ayyub
I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough...