DP83907VF National Semiconductor, DP83907VF Datasheet - Page 41

• Manufacturer Part Number: DP83907VF
• Description: IC CONTROLLR AT/LANII TP 160PQFP
• Manufacturer: National Semiconductor

Specifications of DP83907VF

• Controller Type: Network Interface Controller (NIC)
• Interface: Twisted Pair
• Voltage - Supply: 4.75 V ~ 5.25 V
• Current - Supply: 150mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 160-MQFP, 160-PQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *DP83907VF

6 0 Operation of DP83907
6 2 BUFFER MEMORY ACCESS CONTROL (DMA)
The buffer memory control capabilities of the DP83907
greatly simplify the use of the DP83907 in typical configura-
tions The local DMA channel transfers data between the
FIFO and memory On transmission the packet is DMA’d
from memory to the FIFO in bursts Should a collision occur
(up to 15 times) the packet is re-transmitted with no proces-
sor intervention On reception packets are moved via DMA
from the FIFO to the receive buffer ring (as explained be-
low)
A Remote DMA channel is also provided on the DP83907 to
accomplish transfers between a buffer memory and an in-
ternal Data Port when using the DP83907 in I O Mode This
FIGURE 28 DP83907 Receive Buffer Ring
FIGURE 27 DP83907 Bus Architecture
(Continued)
41
Remote DMA channel is not used when the DP83907 is
used in a shared Memory mode In this second mode the
buffer memory is dual ported and directly mapped into the
system memory In this mode the system CPU directly ac-
cesses the RAM under software control to transfer packet
data
The following sections describe the operation of the Local
DMA channel for packet reception which is used in both
modes For Shared Memory mode the description of the
Remote DMA does not apply
For reference an example configuration using the DP83907
is shown in Figure 27
TL F 12082 – 22
TL F 12082 – 23