Programming Model Rules (1)

Murrough Landon - 17 Sep 1999

We have evolved (from experience!) a set of rules and conventions which the programming models of all modules produced by our engineers should adhere to. Most of pretty obvious.

The aim is to aid the software control of the module - especially software development.

No ``write only'' registers

• This includes memories, FIFOs, etc.

• The idea is that all information about the state of the module must be readable by computer. This may not always be appropriate for highly volatile data, but in many cases the decision whether to trust the data should be left to the software.

Separation of status/control/reset

• Dont mix read only and read/write bits in single registers.
• Status registers are read only, control and other registers are read/write.
• Some registers are used for dataless actions, eg resets. The latter are the only ``write only'' exceptions to the above rule.