RoseOnRails – Answering some doubts

Hi everyone!

This week my group and I had some questions to answer in order to best define our project.

First, let’s see a schema of our project :

Schéma de notre projet

As we can see we proposed that our Central Station be composed of a Raspberry Pi with a Dongle BLE. This way we can offer a built in product at the end of our project. Even if in the first part we will work from an usual computer.

Regarding the BLE communication

According to the document Creating Bluetooth Low Energy Applications using nRF51822 provided with the evaluation kit of Nordic, we assumed that our PCBs will first advertise in order to enable the Central to connect to them. (cf “For a Central to be able to connect to a Peripheral, the Peripheral must be advertising.”)

Then, they will be in connected mode even if the PCB is able to decide to ignore some connection intervals in order to reduce the consumption of energy. ( cf “However, if current consumption is important and a Peripheral has no data to send, it can choose to ignore a certain number of intervals.”)

On Friday, Noemie and I have made some research in order to fine a LED strip which fits to our needs. We’ve found this one which enable us to control each LED easily. We still have to make some precise calculation in order to know if we can modulate the light fast enough to enable the train to detect his position. A first rough calculation made us think it’ll be too short.

So on Alexis’ advice we are going to look for an other kind of detection. Theses ones would be composed of coils which are going to emit a modulate magnetic field and the train will have a Hall sensor.

We’ve a to find an equivalent of this a bit cheaper on Alibaba website because we measured that we have almost 28 meters of rails to cover.

I’ve also enjoyed the Friday labwork with my first exercise on PCB and I hope we’ll soon manage to make our PCB.


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