Week 4: Data Transfer

Group meeting

In the week 4 meeting of our group, the following points have been discussed:

• Summary of the job done in week 3.

• Discuss how to connect 3 Raspberry Pi together.

• Discuss how to receive the data comes from the visual system group.

• Discuss how to calculate the total rotation adjustment degree on the spoke to reduce the distortion.

• Discuss how to reduce the delay between data communication.

Supervisor meeting

• Professor told us to add a comparator and a variable resistor into the circuit. In this way, the voltage cross the GPIO input for the IR system will be 0V or 3.3V as a digital signal. Other voltage value as the interference signal will be ignored.

• Professor gave us some advice for multiple Raspberry Pi connection by using the serial communication.
  

Lab Day

IR system

• Rebuilt the whole circuit on the bread broad try to add the comparator LM393 to improve the GPIO input signal.

• However, we failed to add the comparator LM393 into the circuit. We try to add the variable resistor to change the Vref voltage to be the max voltage value of photo-transistor 4.8V. But the output of the LM393 still varied around the 0V, the GPIO input cannot receive the high-level voltage to count the spoke. Moreover, time is limited, we do not have enough time to improve the circuit. In this way, we had to give up to move forward into next stage. Fortunately, there will be no influence for the whole system programming without the LM393.

Data Transfer

• To transfer the data between each Raspberry PI, we choose to use the minicom to apply the serial communication. The RX,TX and Ground pins are used in this condition. However, it is still not successful after we tried for a long time. The text can be transferred, but the data can not be transferred. In this way, we decide to ask professor Smith for help.

Problems, Issues and Concerns

• The comparator makes the circuit short sometimes.

• We are failed to add the comparator LM393 into the IR system.

• There are some problems when we use minicom to communicate with each Raspberry Pi. The text can be sent and received, but the data can not.

Plan for next week

• Try to add the comparator into IR system one last time.

• Work out the data communication problem to ensure our group can receive the data from the visual system group.

• If the Raspberry Pi communication can work, join in the spoke adjustment calculation part to realise the final target and finish the whole project.