Protocle de communication

La liaison entre l'arche et le PC est faite par une ligne série RS-232. Voici le protocle de dialogue série avec l'arche

Generals

The COM-port must be configured to 19200,8,n,1.
The data is sent as ”normal text strings”, i.e. ascii, not binary.
Each command and reply starts with a '#' and ends with a '$'.
All data/numbers are given in hex.
The length of the replies are fixed. E.g. if car 1 passes after 10 milliseconds, the result will be: #P0100000A$
ID 0 is an invalid ID. All ID’s must be between 1 and 255.

Commands from PC to LapZ:

#S$ Start race.
#F$ Stop race
#Ixx$ Write new ID into the car placed under the bridge. xx is a number between 1 and 255 (hex). E.g.: #I0B$
#G$ Get a single ID from the car placed under the bridge.

Commands from LapZ to PC during a race

#Pxxyyyyyy$ A car has passed. xx = The cars ID, yyyyyy = number of milliseconds since the start (hex). E.g.: #P1300023D$
#Uyyyyyy$ Clock update. Comes approximately each 7 seconds. yyyyyy = number of milliseconds since the start (hex). E.g.: #U00032B$

Commands from LapZ to PC after programming new ID (#Ixx$)

#Oxx$ New ID was programmed successfully. xx = The ID that was programmed (this can typically be used to verify that the correct ID was programmed).
#N$ New ID was NOT programmed. This comes from a timeout after 200 ms.

Commands from LapZ to PC after requesting a single ID (#G$)

#Hxx$ The ID of the car under the bridge.
#J$ No response from any cars. This comes from a timeout 200 ms after #G$ was sent.

Blindage de l'arche

L'arche de comptage a la facheuse tendance a générer des interférences avec les voitures. Il est donc conseillé de blinder l'interrieur de l'arche. Pour cela vous pouvez utiliser du simple papier aliminium. Enroulez plusieur tours entre les émetteurs infra-rouge. Relier touts les éléments par un gros fil de cuivre qu'il faut souder au blindage du connecteur série.