Specifications

screen. There are other ways to get the battery data. This method seems to be the

easiest, but it is not the most accurate. The most accurate method is to use the specific

gravity of the battery, which the processor can take up to 2 hours to calculate. We felt

as if this is to much time to get the percent of the battery left because that amount of

time to get a steady state to read the level is to much time. If the battery was a smaller

battery and needed to be accurate we would of went with this but according to the

specs we don‟t think that this is necessary.

Another function that needs to be written is about the fault codes that we will need to

worry about. One of the main fault codes will be heat in the box, if the heat in the box

gets to a critical level we will need to let the user know that if they don‟t turn off the

machine or do something to cool it down it can fail. This is important because we need

to take safety into account. We will use the temperature sensor that is built into the

MSP430 to complete this task. Since the board will be inside of the box as well as all of

the electronics it is great to have a onboard temperature sensor. If the temperature gets

to high then it will cent a fault code to the screen letting the user know that the

temperature is to hot and something needs to be done to get the temperature down. We

will have fans and vents such that this doesn‟t happen but if a fan fail then it is a

possibility and we need to account for it.

We will also implement a time system that will tell the user that if he keeps up current

usage how much time it will take to empty the system. This is going to be a complicated

algorithm because we will need to calculate the amount of power that is entering the

system, the current state of the battery level, and also the amount of power leaving the

system. First we will calculate the amount of power in watts entering the system. This

will subtract from the amount of power leaving the box to get a net value of where the

system is. If the value if negative more power is being consumed rather than generated

and this will display to the user that more power is being used and if he keeps up this it

will be empty soon. If the output if positive it will show up as power is being generated

and there is no time till empty because power is entering the system.

Another fault code we will have to have is if the battery needs to be replaced. This will

be determined by where the level of the battery is. When a battery cannot hold charge

anymore the voltage across the terminals fall below the threshold, which we will display

to the user and they will need to replace the battery. The battery will need to be in a

assessable location such that the user can replace it when needed.

Below is the type of LED we will be using to show different fault codes and if the box is

saving power or using power. If it is saving power we will be using a green led and if it is

using power we will use a red one. There will also be a led for if they are any problems

with the box that needs to be addressed before the user turns it on. The LCD display is

great but it is hard to read at a glance. Led bulbs on the other hand once you see it lit

you will know exactly what is going on with the system. You wont need to read a screen

or try to figure out what is going on. At a quick glance you will see what is wrong with

the screen. These will all be programmed into the microcontroller, if the microcontroller

receives a signal to light up a fault code it will send it to the screen. This will also be a