ISDN HDLC FIFO CONTROLLER DRIVER

The CPU should read the Frame length register 0x4 to check the size of the frame. This protocol uses the handshack protocol of the Wishbone SoC bus. This is suitable for dropping bad frames for any reason or frames with incorrect addresses. The core should not have internal configuration registers or counters, instead it provides all the signals to implement external registers. Two interrupt lines are used, one to signal transmission done and one to request transfer of received frame to memory.

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On 9 Apr Abort pattern generation and checking 7 ones Address insertion and detection by software CRC generation and checking CRC or CRC can be used which is configurale at the code top level FIFO buffers and synchronization External Byte aligned data if data is not aligned to 8-bits error signal is reported to the backend interface Q.

The core will be made of two levels of hierarchies, the basic functionality and ocntroller Optional interfaces and buffers. The FCS and Buffering can be changed by replacing the corresponding files.

The FIFO size is suitable for operating frequencies 2. Receive channel supports only 8-bits aligned data.

HDLC controller :: System spec and interaces :: OpenCores

Since the receipt ion is synchronous only, the channel fifp the external clock and a byte must be read from the channel within the first 7 clock pulses after the ready signal is asserted. The current implementation supports the following configuration: The design is divided into three main blocks, serial Receive channel, Serial Transmit channel and the Hdlf blocks. The choice between master and slave is left for the system integrator and must do the configuration and glue logic as defined in the tables.

All bytes will be available once the transmit is enabled. It is optional for the CPU to check the status bits of Tx status register. Valid Frame signal must be asserted for 8 clocks after any valid write operation.

This protocol uses the handshack protocol of the Wishbone SoC bus. If the CPU does not read all frame bytes as soon as possible the internal buffer will overflow and FIFOOverflow bit will be set and the current frame should be dropped.

Each frame starts with a starting flag and ends with starting flag These interrupts are also reflected in Status registers to support polling mode for the controller. The CPU should read the Frame length register 0x4 to check the size of the frame.

Status and control registers are available to control these FIFOs. FrameErr is signaled also when non 8-bit aligned data is received and when FCS error is found. The value of this regiter is valid only after the RxReady bit is set and remains valid till the dhlc read from the Data buffer.

Then passes the data field between the two controllers through optional DMA transfer. After writing to this bit no further write operation to Tx FIFO buffer register is allowed till TxDone is set all writes will be ignored.

Document Outline

The software configures the TDM controller to select the channel. Transmit channel supports only 8-bits aligned data.

Two interrupt lines are used, one to signal transmission done hvlc one to isvn transfer of received frame to memory. If no data is read during this period while ValidFrame signal is active FrameErr is signaled reported to the backend as long the ValidFrame is active. Backend interface uses the Wishbone bus interface which can be connected directly to the system or via FIFO buffer.

If no data is inserted during this period while ValidFrame signal is active abort pattern is transmitted and reported to the backend via AboredTrans signal as long the ValidFrame is active. This protocol uses the hand shack protocol of the Hvlc SoC bus. Since the transmission is synchronous only, the channel uses the external clock and a byte must be written to the channel within the first 7 clock pulses after the ready signal is asserted.

These Flip Flops are clocked with the same clock of the interface that read these signals.

The interface supports the following wishbone signals. System spec and interaces. These two blocks FIFOs and registers are built around the HDLC controller core which make them optional if the core is to be used in different kind of applications.

Performing extra reads read from empty buffer produces invalid data. This controller is used for low speed application only relative to the backend bus.