Software



Team 3

Progress Report

April 9, 2010

Introduction

Since our last progress report, we have made many milestones. We were able to transmit the radio signal over the approximate distance required in Tanzania; the coding for caching TCP packets has been completed, as well as coding for automatic control of the transmitting circuitry. The microcontroller is near completion; also we have developed a scheme for the overall implementation of the layout of the receiving and powering circuitry that will be deployed at Baraka Primary School.

Hardware

Relays

The relays in a proposed outlet box are used to switch on the networking equipment. We have successfully sent a 5V signal from the microcontroller and amplified the amperage via a transistor to switch 12V relays that require approximately 400mA.

Another set of relays will send power to the receiver and the decoder at Baraka; the intent is to shut off these two components in order to preserve more power during night hours. The same transistor amplifier scheme will also be used for these set of relays.

Also, a third set of relays will be used to power up the transmitters at Manyara and Rift Valley when an Internet request is made. This too uses the transistor amplifier method.

Microcontroller

The foundation inputs for the microcontroller are all functioning. Internet requests are acknowledged from Baraka, Rift Valley, and Manyara separately, and each school has a separate timer for the timeout. The life of the battery is also continuously tested throughout the functioning of the program and the microcontroller shuts down everything when battery life drops below 40%. Remaining tasks include:

• Switch out the LED lights for relay outputs.

• Find the discharge curve for the battery present in Tanzania to determine the 40% and 60% values.

• Include external timer feature.

• Include Sleep mode for system inactivity.

Radio

We have successfully transmitted 4.5 miles using a high gain folded-dipole Yagi antenna. Furthermore, the decoder is able to decipher signals without any interference. We still plan to test different configurations of amplifiers and antennas to determine which is best for the project, but also for keeping the load light when traveling to Tanzania.

External Timer

The external timer has posed several difficulties. Once the timer IC’s were received, application notes were found on the internet to interface the microcontroller with the DS1307 Programmable timer. After wiring the timer to the microcontroller, there was an issue with the programming syntax, especially when the schematic used for interfacing was using a different model microcontroller. In order to remedy this, other solutions for external triggering were being considered. In essence, the triggering mechanism is an alarm clock, so we disassembled an alarm clock to modify it to send an output signal to the microcontroller; however other conditions had to be satisfied that the alarm clock did not have the capability to fulfill. Nevertheless, solutions are underway and our progress for the external timer is continuing. The next step is to consider a commercial external triggering timer for more than one event (i.e. powering down the system at night and powering up the system in the morning). Such options include 24 hour sprinkler timers and other electromechanical programmable timers.

Software

Since developing an application to detect user internet requests, effort has been placed on identifying a way to send a “turn on signal” to the transmitter. This will essentially be a voltage that powers the transmitter. At first this was going to be done with a USB programmable device, but while waiting for the shipment, an alternative method was devised. After researching serial communications, a Python library called PySerial was found that could provide 6V of power over a serial port with three lines of code.

The next step is to integrate this with the modified version of Tinyproxy. Tinyproxy was modified with the use of Python, so implementing PySerial into Tinyproxy should be done rather quickly and easily. Remaining is an administration program to turn on the Internet that can be run when Tinyproxy is taken down for system updates and maintenance.

Conclusion

All is going fairly well. Aside from other individual objectives, all that remains is to enclose all the components in their respective enclosures in a way that is convenient for access and to minimize as much space as possible. We should be ready for Design Day!

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