data list ack update and status
| LIST_INDEX__TX_ACK_3_0 | Write: Indicates the buffer index for which the ACK bit is being updated by firmware. The default number of buffers in the IP is 5. The index range is 0-4. Read: Reads TX_ACK[3:0] If a particular bit is set, then the packet in the selected buffer has been transmitted (at least once) by the hardware and hardware is waiting for acknowledgement. Example1 : If the read value is : 0x03, then packets in FIFO-0 and FIFO-1 are acknowledged by the remote device. These acknowledgements are pending to be processed by firmware. Example2 : If the read value is : 0x02, then packet FIFO-1 is acknowledged by the remote device. This acknowledgement is pending to be processed by firmware. NOTE: The SENT status bit and ACK status bit have to be taken together to understand the meaning of packet status. The table below describes how the two bits are sequentially updated by either hardware/firmware to complete one data transmission. SENT ACK Description 0 0 Buffer is empty. No packet is queued in the buffer 1 0 Packet is queued by firmware. 1 1 Packet is transmitted by hardware. Hardware is waiting for acknowledgement. 0 1 Hardware has received ACK. Firmware has not yet processed the ACK. 0 0 Firmware has processed the ack. The buffer is again empty. |
| SET_CLEAR | Write: Firmware uses the field to clear and ACK bit in the hardware to indicate that the acknowledgement for the transmit packet has been received and processed by firmware. Firmware clears the ACK bit in the hardware by writing in this register only after the acknowledgement is processed successfully by firmware. For clearing ack for a packet transmitted in fifo-index : ‘3’, firm-ware will write ‘3’ in the ‘list-index’ field and set this bit (BIT7) to 0. This is the indication that the corresponding packet buffer identi-fied by List-Index is cleared of previous transmission and can be re-used for another packet from now on. The ACK bit in hardware is set by hardware when it has success-fully transmitted a packet. |