Introduction
In many situation it’s needed to implement a bus register bank. The BusSlaveFactory is a tool that provide an abstract and smooth way to define them.
To see capabilities of the tool, an simple example use the Apb3SlaveFactory variation to implement an memory mapped UART. There is also another example with an Timer which contain a memory mapping function.
You can find more documentation about the internal implementation of the BusSlaveFactory tool there
Functionality
Currently there is three implementation of the BusSlaveFactory tool : APB3, AXI-lite 3 and Avalon.
Each implementation of that tool take as argument one instance of the corresponding bus and then offer following functions to map your hardware into the memory mapping :
| Name | Return | Description |
|---|---|---|
| busDataWidth | Int | Return the data width of the bus |
| read(that,address,bitOffset) | - | When the bus read the address, fill the response with that at bitOffset |
| write(that,address,bitOffset) | - | When the bus write the address, assign that with bus’s data from bitOffset |
| onWrite(address)(doThat) | - | Call doThat when a write transaction occur on address |
| onRead(address)(doThat) | - | Call doThat when a read transaction occur on address |
| nonStopWrite(that,bitOffset) | Permanently assign that by the bus write data from bitOffset |
|
| readAndWrite(that,address,bitOffset) | - | Make that readable and writable at address and placed at bitOffset in the word |
| readMultiWord(that,address) | - | Create the memory mapping to read that from ‘address’.If that is bigger than one word it extends the register on followings addresses |
| writeMultiWord(that,address) | - | Create the memory mapping to write that at ‘address’.If that is bigger than one word it extends the register on followings addresses |
| createWriteOnly(dataType,address,bitOffset) | T | Create a write only register of type dataType at address and placed at bitOffset in the word |
| createReadWrite(dataType,address,bitOffset) | T | Create a read write register of type dataType at address and placed at bitOffset in the word |
| createAndDriveFlow(dataType,address,bitOffset) | Flow[T] | Create a writable Flow register of type dataType at address and placed at bitOffset in the word |
| drive(that,address,bitOffset) | - | Drive that with a register writable at address placed at bitOffset in the word |
| driveAndRead(that,address,bitOffset) | - | Drive that with a register writable and readable at address placed at bitOffset in the word |
| driveFlow(that,address,bitOffset) | - | Emit on that a transaction when a write happen at address by using data placed at bitOffset in the word |
| readStreamNonBlocking(that,address, validBitOffset,payloadBitOffset) |
- | Read that and consume the transaction when a read happen at address. valid <= validBitOffset bit payload <= payloadBitOffset+widthOf(payload) downto payloadBitOffset |
| doBitsAccumulationAndClearOnRead (that,address,bitOffset) |
- | Instanciate an internal register which at each cycle do : reg := reg | that Then when a read occur, the register is cleared. This register is readable at address and placed at bitOffset in the word |