Design Time Checking: Consequences and Benefits

During the design time, Processor Expert performs instant checking of the project. As a result of this checking, error messages may appear in the Error Window or directly in the third column of the Bean Inspector (on the faulty items line). Sometimes, it may happen that only one small change in the project causes several (general) error messages. The most common reasons for this behavior are stated below.

On-Chip Peripherals

Some beans use on-chip peripherals. In the Bean Inspector you can choose from all possible peripherals that can be used for implementation of the function of the current bean. Processor Expert provides checking for required peripheral features such as word width and stop bit for serial channel, pull resistor for I/O pin and others.
Processor Expert also protects against the use of one peripheral in two beans. If the peripheral is allocated for one bean then the settings of this peripheral cannot be changed by any other bean. The state of an allocated peripheral should never be changed directly in the user code. (Using special registers, I/O ports etc.) We recommend to always use methods generated by Processor Expert. If the functionality of generated methods is not sufficient for your application, you can use PESL (Processor Expert System Library). See chapter Low-level Access for details.

In some timer beans you can choose if you want to use only a part of the timer (compare register) or an entire timer. If you select the entire timer, the driver can be optimized to best work with the timer: it can, for example, invoke reset of the timer whenever is it needed by the bean function.

Interrupt Priority

If the target CPU shares interrupt priority between several interrupt vectors or shares interrupt vectors, Processor Expert provides checking of interrupt priority settings. If you would like to have more detailed information about Interrupt Priority see the Priorities page.

Memory

Processor Expert always checks the usage of internal and external memories accessible via CPU address and data bus. Position and size of internal memory is defined by the CPU type and can be configured in the CPU Properties (if supported). External memories must be defined in CPU Properties.
Any bean can allocate a specified type of memory. See bean descriptions for detailed information about requirements for types of memory. Processor Expert provides checking of memory and protects you from making a poor choice. (For example: if a bean requires external Flash, it is not possible to enter an address in internal RAM).

The bits can also allocate memory. Therefore you can be sure that only one bean uses an allocated bit of a register in external address space.

Timing

The settings of all timed devices are checked. If no error is detected, it means that you can work with the given settings without a problem in run-time. Generated drivers are provided in such a way that they cannot influence each other - this means that, even if several beans share one physical device, changes in the bean settings using the values given (and checked) by Processor Expert are possible in run-time without affecting any other bean.

Dealing with errors:

• One bean reports an error in the Project panel
  Take a look at the bean inspector dedicated to the bean. Highlighted (red) values report an error (move a mouse pointer on to the message to get more information).
• Several beans report an error in the Project panel
  
  • Only one bean is incorrectly set
    If you cannot directly detect the faulty bean, just go through all the beans reporting an error. If a message 'Timing setting failed because of another bean' is reported then this bean seems to be OK, but, due to hardware dependency, it is temporarily blocked by the faulty bean. If another message is reported (for instance: 'Timing settings failed in X speed mode - ...') read the message carefully. It describes the error.
  • More than one bean is incorrectly set
    If all the beans report the error message 'Timing settings failed in X speed mode', then it means that these beans are mutually dependent on the hardware level and their settings do not tally. Usually, you will see a message saying 'ERROR: The following devices mutually block their timing settings: list_of_beans' in the Error window. You may be helped in your error diagnosis by looking at the hardware dependencies with the Target CPU Timing Model. A typical example of hardware dependencies is timers sharing a single prescaler.
    If not all the beans report such a message, then several beans are incorrectly set and you should read the messages carefully to detect the faulty beans.

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