KSZ8851-16MLLU TR Micrel, KSZ8851-16MLLU TR Datasheet - Page 33

• Manufacturer Part Number: KSZ8851-16MLLU TR
• Description: Ethernet ICs Single-Port Ethernet Controller (Automotive Grade)
• Manufacturer: Micrel

Specifications of KSZ8851-16MLLU TR

• Rohs: yes
• Product: Ethernet Controllers
• Package / Case: LQFP-48
• Mounting Style: SMD/SMT

Micrel, Inc.
KSZ8851-16MLL/MLLI
Driver Routine for Receive Packet from KSZ8851-16MLL to Host Processor
The software driver receives data packet frames from the KSZ8851-16MLL 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 KSZ8851-16MLL RXQ into system memory at
task level. The following Figure 9 shows the step-by-step for receive packets from KSZ8851-16MLL 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
May 2012
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M9999-050112-2.1