ELECINF344/381

Partie interactive du site pédagogique ELECINF344/ELECINF381 de Télécom ParisTech (occurrence 2011).

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TSV Safe Express: Demystifying Conundrums

During the last two days, we have faced a lot of problems with the sensors of the track. We had two types of interrupts that were causing us problems:-
1. Debouncing Interrupts
2. Fake Interrupts

Problem: We have configured STM32 GPIO ports to Internal Pull-Up. All our sensors cards are powered by the Central Station Card through the CAN bus. We observed that there is some kind of parasitic signal that comes from the booster towards our Central Station which produces a glitch in the power towards the Nodes (Sensors card in this case). Due to this glitch in power, the GPIO ports which were pulled high become low and thus Fake Interrupts are produced. Thanks to Alexis who stayed till 5 in the morning to help us debug the problem.

The first one was solved by making sure that the any interrupts (that is not fake) from the sensors is processed only if there is atleast a gap of 100ms since the last time it was called. For the second one, which is more tricky, we use a simple method (a FreeRTOS task) which checks for glitches. This method was proposed by Samuel and we thank him for assisting with our software.

Right now, we are trying to do all the mapping of Reed Sensors and Lights to the XML Layout of the track. This is required as the central station needs to talk to server giving him with sensor input.

TSV Safe Express: Traffic lights set up and ready to go.

After stabilizing the NMRAnet  CAN bus , at least to what concerns the traffic lights, we connected all the traffic lights of the circuit to the cards and verified that indeed this part of the project has been finalized. 6 traffic light cards successfully respond to the assigned by the central station events, and glow led’s accordingly. Now what remains, concerning this part of the project is, their mechanical placement and installment.

Currently we are focusing mainly on the development of the sensor cards and we hope that won’t take much time. We got our first interrupts from the train passing over the reed sensors. Hopefully by the end of the week end we will be able to wrap everything up and start communicating with Samuel’s application.

Here comes a video of Siwar explaining our work up to this moment.