Objectives of Lab 3:
• Compile DemoAppFFS, run to ensure correct file
• Modify DemoAppFFS to save an analog input and send an email of the value that was inputted
• Modify DemoAppFFS with Orbcomm specific commands
Process:
During the lab time our team decided to split the workload by assigning the DemoAppFFS to the coding sub-team while the sub-teams in charge of the actuator and weather sensors focused on research and designing their appropriate components. The DemoAppFFS was straightforward and it was easy to implement the necessary functions from DemoAppFFS into our code that we intend to use for the project.
The weather sensor sub-teams determined two possible approaches for implementing a wind speed sensor. Our first design was to utilize a low resistant (to torque, ie easy to turn) dc motor that would be connected to the shaft of the wind speed sensor. When the shaft rotated, a voltage would be generated by the dc motor that is dependent on the speed of rotation. The second design was to implement a specific hall-effect sensor (non-latching, analog). A metallic gear would be attached to the shaft so that when the shaft rotated the magnet imbedded in the hall-effect sensor would detect the gears rotation. From this, the frequency of rotation can be determined which could be translated to wind speed. The wind sensor shaft is driven by an array of cups.
Wind direction is a secondary goal for our project however the design to implement the sensor was discussed so that it could be easily added once the wind speed sensor is functional. The design is not finalized but our team suggested that it could be implemented by means of potentiometer and a wind vein.
Challenges:
A challenging part of the DemoAppFFS was to extract the voltages and send them in an email. This could be done easily by selecting each value in the voltage array. However, we wanted to utilize a for loop to make our code cleaner and easier to debug. In order to do this the strcat function was needed; however, it kept causing a stack overflow. Eventually, the code was fixed after we found the error.
Other problems involved time delays in the modem. The emails sent out sometimes took over 10 minutes to be received. This is most likely due to errors that our out of our control but we are still trying to figure out how to time our emails to increase efficiency.
Additional Updates:
Our coding sub-team was able to figure out how to configure the digital ports to either be outputs or inputs. Functions for printing timestamps and changing the subject of the email were also determined. Another function that was implemented was how to decipher emails that were sent to the modem. So far we are able to receive the emails and store the body of the message in a string. Therefore, all that is left is to determine how we want to process the string.
A trip to Lee’s Electronics was conducted to search for possible sensors that they sell there and certain specs of each device.
Team Meeting Summary:
The team meeting was held Monday January 27th and all members were able to attend. The scope of the project and the components that need to be completed were discussed. From this, the relative tasks were delegated to sub-teams. Our team decided the best approaches to implement the weather sensors and the actuator. Deadlines were also decided to ensure that the project is finished ahead of schedule in case of any emergencies.