KSZ8851-16MLLJ_10 MICREL [Micrel Semiconductor], KSZ8851-16MLLJ_10 Datasheet - Page 35

• Manufacturer Part Number: KSZ8851-16MLLJ_10
• Description: Single-Port Ethernet MAC Controller with 8-Bit or 16-Bit Non-PCI Interface
• Manufacturer: MICREL [Micrel Semiconductor]

Micrel, Inc.
KSZ8851-16MLLJ
Driver Routine for Receive Packet from KSZ8851-16MLLJ to Host Processor
The software driver receives data packet frames from the KSZ8851-16MLLJ device either as a result of polling or an
interrupt based service. When an interrupt is received, the OS invokes the interrupt service routine that is in the interrupt
vector table.
If your system has OS support, to minimize interrupt lockout time, the interrupt service routine should handle at interrupt
level only those tasks that require minimum execution time, such as error checking or device status change. The routine
should queue all the time-consuming work to transfer the packet from the KSZ8851-16MLLJ RXQ into system memory at
task level. The following Figure 9 shows the step-by-step for receive packets from KSZ8851-16MLLJ to host processor.
Note: Each DMA read operation from the host CPU to read RXQ frame buffer, the first read data (byte in 8-bit bus mode,
word in 16-bit bus mode and double word in 32-bit bus mode) is dummy data and must be discarded by host CPU.
Afterward, host CPU must read each frame data to align with double word boundary at end. For example, the host CPU
has to read up to 68 bytes if received frame is 65 bytes.
Figure 9. Host RX Single or Multiple Frames in Auto-Dequeue Flow Diagram
March 2010
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M9999-030210-1.0