AME 3623: Project 2-3

All components of the project are due by Thursday, February 19th at 8:00 am
Groups are the same as for project 1.
Discussion within groups is fine.
Discussion across groups may not be about the specifics of the solution (general programming/circuit issues are fine to discuss).

At the end of this project, you should be able to:

through low-level functions, control the speed and direction of DC motors through an H-bridge circuit, and
use a high-level program to test the functionality of the DC motor control interface.

Component 1: Microcontroller Circuit

The current amplifier board is composed of two full H-Bridge circuits. We will be using one full H-Bridge to control the lift fan (allowing us to control rotation speed and direction). We will split the other H-Bridge into two "Half Bridges": one for each of the left and right fans. This will allow us to control speed of these two fans, but not direction.

The detailed documentation for the motor control board can be found on the Pololu Web site.

The diagrams for the power wiring harness and the amplifier board are shown below.

Add wires to connect the motor control board to the fans and to the batteries:

Connect GND and VIN directly to the battery (not to your 5V regulated power supply!!!)
Connect the lift fan to port 2 (OUT 2A and 2B)
Connect the right fan: red wire to OUT 1A and black wire to GND
Connect the left fan: red wire to OUT 1B and black wire to GND

Connect the current amplifier board to your Atmel chip (the 15 pin connector on the left side of the board in the picture below):

Connect 1PWM and +5V(IN) to your Atmel's +5V power supply
Connect GND and GND to your Atmel's ground
Choose one of: timer1, 3, 4 or 5. For the chosen timer, you must have all three PWM pins available (they are labeled OCXA, OCXB and OCXC on the Arduino circuit diagram, where X = 1, 3, 4 or 5).
Connect the following to your Atmel to free digital output pins (but do NOT use B0 ... B3):
- 1INB ("input2"): PWM input for the left fan. Connect to OCXA
- 2PWM ("input3"): PWM input for the lift fan. Connect to OCXB
- 1INA ("input1"): Pulse-Width Modulated (PWM) input for the right fan. Connect to OCXC
- 2INB/2INA ("input4" and "input5": direction control for the lift fan (0/1: one direction; 1/0: the other direction).

Power Wiring Harness

Power Amplifier Board

Component 2

Create the function interface that will generate the PWM signals for each of the three PWM inputs to the motor control board.

Define a new variable type in a new file called "project.h"

typedef enum {
   BRAKE,
   HOVER
} LiftMotorDirection;

LiftMotorDirection is the new variable type. BRAKE and HOVER are the two values that LiftMotorDirection variables can take on. Remember to include "project.h" in your C file.

Implement the following functions:

int16_t clip(int16_t value, int16_t min_value, int16_t max_value) that returns
- min_value if value is smaller than min_value
- max_value if value is larger than max_value
- value otherwise
void set_lift_motor_direction(LiftMotorDirection direction) that sets the direction bits for the lift fan.
If direction == HOVER, then the lift fan should push air into the chamber, causing the craft to hover (assuming an appropriate level of thrust).
If direction == BRAKE, then the lift fan should pull air out of the chamber, causing the craft to be pulled to the ground.
void set_lift_motor_magnitude(int16_t magnitude) that sets the thrust magnitude for the lift fan. This function must ensure that magnitude falls within the range of 0... 1023 (which correspond to 0% ... 100% duty cycle). If the value does not, then it should be clipped to this range.
void set_side_motor_magnitudes(int16_t magnitude_left, int16_t magnitude_right) that sets the thrust magnitude for the left and right fans. This function must ensure that magnitude_left and magnitude_right fall within the range of 0... 1023 (which correspond to 0% ... 100% duty cycle). If either does not, then the offending value should be clipped to this range.

Note:

Initialization of the three PWM channels must happen within your main() function (see the lecture notes on timers).

Component 3

Implement the following in your main() function:

Within your main while(1) loop:

If your switch is pressed:
- Set middle fan thrust direction to HOVER
- Slowly ramp the lift fan thrust upwards until 25% duty cycle
- Wait until the switch is released
- Slowly ramp the lift fan thrust downwards until zero
- Set thrust direction to BRAKE
- Slowly ramp the lift fan thrust upwards until 25% duty cycle
- Wait until the switch is pressed again
- Slowly ramp the lift fan thrust downwards until 0% duty cycle
Note: use your LEDs to indicate which phase of the program that you are in.
If your switch is not pressed:
- Slowly ramp the left fan up to a duty cycle of 25%
- Slowly Ramp the left fan down to 0%
- Slowly ramp the right fan up to a duty cycle of 25%
- Slowly ramp the right fan down to 0% duty cycle
Note: use your LEDs to indicate which phase of the program that you are in.

What to Hand In

All components of the project are due by Thursday, February 19th at 8:00 am.

Demonstration/Code Review: All group members must be present. Given time, this can be done during class.
Code: Check your documented code into your group dropbox on D2L for project 2-3.
Remember that documentation is about helping you and others looking at your code to understand what it is doing. Therefore, it will generally describe the logic of the code (and not-necessarily the low-level details). For this class:
1. At the top of your C file, document the project number, group members, date and the group member responsible for the code.
2. Each function must be documented (at the top of the function) as to what it does logically, what the meaning is of its inputs, and what the returned value is. If the function has external effects (e.g., commanding an actuator or modifying a global variable, these should also be documented here)
3. In-line comments should be used to describe logically what is happening at that line or group of lines.
Personal report: fill out the CATME survey.

Grading

Personal programming credit:

Each person must accumulate at least three personal programming credits over the course of the semester (this project offers one)
To receive credit, you must be the primary designer, implementer and debugger of the component. This does not mean that your other group members should not be looking over your shoulder. But: you must do the "driving."

Group grade distribution:

35%: Project implementation
30%: Demonstration of working project (to either of the TA or the instructor)
35%: Code documentation

Group Grading Rubric

Grades for individuals will be based on the group grade, but weighted by the assessed contributions of the group members to the non-personal programming items.

andrewhfagg -- gmail.com

Last modified: Thu Mar 26 00:54:36 2015