ECE 477 Digital Systems Senior Design Project 8/09

Homework 5: Theory of Operation and Hardware Design Narrative

Team Code Name: AFCI______Group No. 12____

Team Member Completing This Homework: Ronny Wijaya______

E-mail Address of Team Member: rwijaya@ purdue.edu

Evaluation:

SCORE

/

DESCRIPTION

10 /

Excellent – among the best papers submitted for this assignment. Very few corrections needed for version submitted in Final Report.

9 /

Very good – all requirements aptly met. Minor additions/corrections needed for version submitted in Final Report.

8 /

Good – all requirements considered and addressed. Several noteworthy additions/corrections needed for version submitted in Final Report.

7 /

Average – all requirements basically met, but some revisions in content should be made for the version submitted in the Final Report.

6 /

Marginal – all requirements met at a nominal level. Significant revisions in content should be made for the version submitted in the Final Report.

* /

Below the passing threshold – major revisions required to meet report requirements at a nominal level. Revise and resubmit.

* Resubmissions are due within one week of the date of return, and will be awarded a score of “6” provided all report requirements have been met at a nominal level.

Comments:

Comments from the grader will be inserted here

1.0  Introduction

AFCI is an instrumentation device that is designed for a Hydrogen Fuel-Cell electric vehicle. The main consumer of this product will be the researcher group that develops this specific vehicle. Hoping that the product will provide the practical advantages to accelerate the research, we decided to create an instrumentation system that is focused in monitoring the important physical properties of the vehicle's vital devices as well as giving the ease and the elegance of using the instrument over a user-friendly interface.


In achieving the functional and interface related goal of this project, we decided to put three main groups in collaboration. They are the Atom board, the sensors to monitor the properties and the Printed Circuit Board (PCB) which has the micro-controller and its related interfaces. For the Atom board, we already have a product that we can use right away. We are planning to use this board to organize the touch display interface which would be the main interface of this device to the users. In this homework we are going to go through the theory of the operation of the three groups in more details.

2.0  Theory of Operation

Starting with the Atom board, we decided to use an Atom board so that it can help us in managing the display and taking the user input touch interface. The main reason for choosing an Atom board over a micro-controller to drive the touch sensing display is to accelerate the development and to simplify the interface system. When we pick our Atom board, we want to choose an Atom board that provides enough interfaces for the touch sensing display, the communication between itself and the micro-controller, as well as the development tools which include a flash card slot, a keyboard and a mouse. Since the Atom board itself has a simple desktop architecture, we can simply take it as a desktop machine where an Ubuntu Linux operating system can be installed and do a lot of Graphical User Interface development with it. The main storage device for this Atom board will be a Compact Flash card. Through this card, the Atom board will be able to load the operating system as well.

The second major group of our system is the sensors group. With the consideration that the environment where we are monitoring is really reactive, we have taken many steps to comply with the safety conditions of the particular Hydrogen fuel cell we are monitoring. This fuel cell does not really open up the opportunity for us to use a variety of sensors. The sensor we can get to fit this mechanical feature requires a special fitting that not any sensors have. These sensors will be communicating to the micro-controller through an Analog To Digital (ATD) interface. One of the thermal sensor requires an external Integrated Circuit to drive the ATD signals. We will put it onto our PCB which will be explained on the next paragraph.

Now we go to the third major part of the whole system which is the Printed Circuit Board. The major subsections of the Printed Circuit Board are the micro-controller, the sensor header pins, the SD card module, the RS-232 communication port, the power circuitry and the debugging header pins. Starting from the power, we want to have a regulated 5 Volts input for the micro-controller and the Atom board as well as 12 Volts input for the display and one of our sensor. Since the closest major power supply provided on the implemented vehicle is a 48 Volts battery, we decided to use that combined with regulating electrical circuitry to power our system. Considering that the Atom board uses a different voltage level than the voltage level used by the micro-controller, we decided to use two regulating circuitry. The first one would be responsible to regulate from the main source which is 48 Volts to 12 Volts which will be used by the touch sensing display and one of our sensor. The second regulator would be responsible to regulate from 12 Volts to 5 Volts which is going to be used by the micro-controller and the Atom board.

The micro-controller will be the heart of the sensing operation and it will be explained in the next point.

To provide a portable storage system, we want to put an SD card interface to our system. In achieving this, we plan to use the micro-controller's Serial Communication Interface (SCI) in communicating to the SD card module. With the help of FAT file-system library, we are able to write and read from the SD card through the SD card module. This module is a simple connector that provides us the physical interface to the SD card. It is noted that the module will need 3.3 Volts, so we will use an external circuitry that regulates a 5 Volts input to a 3.3 Volts output.

For the communication between the micro-controller and the Atom board, the system will use a serial communication method. This can be achieved by using the micro-controller's Serial Peripheral Interface (SPI) combined with the Atom board's RS-232 interface. To safely do this, it requires a driver that bridges the SPI and the RS-232 interface. This is where the MAX3232CD driver will work best.

3.0  Hardware Design Narrative

Our micro-controller, the heart of the sensing operation, will be mainly responsible to organize the sensor related processes, to communicate it to the display system and to manage the SD card storage system.

In taking the input signals from the sensors, we decided to use the ATD feature of the micro-controller. This is mainly due to the availability of the sensor interfaces mostly complies with analog signals. The only extra component needed for this interfacing to work is a driver for one thermal sensor. This driver comes in a form of a Dual Inline Package (DIP) so it can be placed to the PCB easily.

To communicate with the Atom board, we want to choose the most reliable interface and that is offered by the SPI of the micro-controller. This interface will give the ease of communication and the portability that may be needed as the research progress.

Alternatives were available for us to interface with the SD card. Among them all, we think that SCI will nicely fit our design. Since we also found modules that support the interface between the SD card and the SPI of the micro-controller, the development process will be accelerated as well.

Additionally, we also provided a Background Debug Mode (BDM) pins that will allow us to program the micro-controller on the PCB right away. This will help us in debugging the chip if something goes wrong.

To give a complete description of what we are using in terms of micro-controller pins, the pins usage table is shown below. This table is to be looked with the assistance of the 9S12C32 manual for 48 Pin QFP Pinouts.

Pin number / Pin name / Usage
1 / PW0/IOC0/PT0 / Debug pin
2 / PW1/IOC1/PT1 / Debug pin
3 / PW2/IOC2/PT2 / Debug pin
4 / PW3/IOC3/PT3 / Debug pin
5 / VDD1 / Power
6 / VSS1 / Power
7 / PW4/IOC4/PT4 / Debug pin
8 / IOC5/PT5 / Debug pin
9 / IOC6/PT6 / Debug pin
10 / IOC7/PT7 / Debug pin
11 / MODC/BKGD / BDM pin
12 / PB4 / Not used
13 / ~XCLKS/PE7 / Debug pin
14 / ECLK/PE4 / Debug pin
15 / VSSR / Power
16 / VDDR / Power
17 / ~RESET / BDM pin
18 / VDDPLL / Not used
19 / XFC / Not used
20 / VSSPLL / Not used
21 / EXTAL / Oscillator
22 / XTAL / Oscillator
23 / TEST/VPP / Not used
24 / ~IRQ/PE1 / Debug pin
25 / ~XIRQ/PE0 / Not used
26 / PA0 / Not used
27 / PAD00/AN00 / ATD pin
28 / PAD01/AN01 / ATD pin
29 / PAD02/AN02 / ATD pin
30 / PAD03/AN03 / ATD pin
31 / PAD04/AN04 / ATD pin
32 / PAD05/AN05 / ATD pin
33 / PAD06/AN06 / ATD pin
34 / PAD07/AN07 / ATD pin
35 / VDDA / Power
36 / VRH / Power
37 / VSSA / Power
38 / PS0/RXD / SCI pin
39 / PS1/TXD / SCI pin
40 / PM5/SCK / SPI pin
41 / PM4/MOSI / SPI pin
42 / PM3/~SS / SPI pin
43 / PM2/MISO / SPI pin
44 / PM1/TXCAN / Debug pin
45 / PM0/RXCAN / Debug pin
46 / VSSX / Power
47 / VDDX / Power
48 / PP5/KWP5/PW5 / Debug pin

4.0  Summary

Our project is a device that monitors the vital information of a research vehicle and shows the information in a format that it will accelerate the research in developing this particular type of hydrogen fueled vehicle. It uses a touch sensing display that is going to collaborate with a micro-controller that takes input from the sensors attached to the vital devices of the vehicle.

The communication between the micro-controller and the Atom board will be using a Serial Communication Interface and an RS-232 interface. In providing the ease of portable storage system, we use an SD card module interfaced with the Serial Peripheral Interface. The sensors will be giving the needed information to the micro-controller through an Analog To Digital interface.

The atom board is responsible to take user input from the touch sensor and showing the user the right information about the properties.

When used correctly, we believe that this device will help the research group to focus more in the development of the vehicle. Hopefully, this device will be more useful than what we expected.


List of References

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Appendix A: System Block Diagram

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