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| - !!EASE - An Easy way to Write Sample Environment Drivers] |
| + !!EASE - An Easy Way to Write Sample Environment Drivers |
| + |
| + !Motivation |
| + |
| + Drivers for sample environment (SE) have some special |
| + demands which were not fully supported by the original SICS |
| + environment controller (EVC): |
| + |
| + * SE is changing, therefore the creation of objects is |
| + dynamic (i.e. after startup). This was already supported, |
| + but with the drawback, that they had to be created again |
| + when restarting SICS. All EASE objects are dynamic |
| + and persistent. |
| + * As SE hardware might be changed, it is not always guaranteed, |
| + that a device is connected and switched on. With the devices |
| + implemented in EVC, waiting for a response blocks the SICS |
| + server. EASE objects work with a simple "finite state machine" |
| + (fsm.c) which simulates a parallel execution of the tasks to |
| + be performed. |
| + * Making an EVC driver means writing a lot of code for |
| + initialization. For a more complex driver you need also much |
| + parameter and subcommand handling. EASE does initialization |
| + and parameter handling for you. |
| + |
| + !pardef |
| + |
| + ''pardef.c'' contains the implementation base class ''ParData'' for a |
| + new type of SICS object. It contains parameter definition, parameter |
| + handling, parameter listing, logging and storing. The parameter definiton |
| + function is the heart of any object based on pardef. This function |
| + is called by the system for different actions which can be performed |
| + on an object. |
| + |
| + !EASE |
| + |
| + ''ease.c'' contains two classes: ''EaseBase'' inherits ''ParData''. It |
| + includes the finite state machine, and the handling of a serial |
| + connection to the hardware. ''EaseDriv'' inherits ''EaseBase''. |
| + It makes the object driveable. |
| + |
| + !fsm |
| + |
| + ''fsm.c'' is the implementation of a simple processor. The tasks |
| + which can be executed are functions (FsmFunc) which contain a switch |
| + statement, where every case is a step of the task to execute. When combined with |
| + EASE, the individual steps normally end with a command written to |
| + the device. After any step, the FsmFunc returns the line number |
| + of the next step. The system calles the FsmFunc again, when the response |
| + is ready. FsmFuncs might be nested. |
| + |
| + !Drivers based on EASE |
| + |
| + For a simple driver, which is only a monitor (like a level meter), |
| + one needs to define |
| + * the parameter definition function |
| + * the start function, an FsmFunc, called after connection to the device |
| + * the read function, called repeatedly. It should read all relevant |
| + information from the device |
| + * for driveable objects, a run function. It should contain all |
| + operation needed to drive to the target value |
| + * the initializer, calling EaseMakeBase or EaseMakeDriv with some class |
| + information and the functions mentioned above as arguments |
| + * the init function, creating the class and inserting the initializer to |
| + the system |
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