W90N740CDG Nuvoton Technology Corporation of America, W90N740CDG Datasheet - Page 105

• Manufacturer Part Number: W90N740CDG
• Description: IC MCU ARM7 TDMI 176-LQFP
• Manufacturer: Nuvoton Technology Corporation of America
• Series: W90r

Specifications of W90N740CDG

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 80MHz
• Connectivity: EBI/EMI, Ethernet, UART/USART, USB
• Peripherals: DMA, POR, WDT
• Number Of I /o: 21
• Program Memory Type: ROMless
• Ram Size: 10K x 8
• Voltage - Supply (vcc/vdd): 1.62 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 176-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

7.6.1
1. The IP address in the IP header is replaced with new inside or outside IP address
2. The port number in the TCP/UDP header is replaced with new port number
3. Recalculate the IP checksum
4. Recalculate the TCP/UDP checksum
NAT Process Flow
While EMC port get valid MAC packets and store them in
memory, it check if {IP, port} hit, and update descriptors
Rx: Look up NAT table process :
1. parsing IP address
2. according IP header length jump to TCP/UDP header
3. parsing TCP/UDP port number
4. compare {IP address, port number} with NAT table content
NATA begins IP address (or Port number) replacement process :
Replace MAC 0 and MAC 1 address in the MAC header
NATA do MAC address replacement process :
Hit or not, hit message in descriptor
(if Rx interrupt is enabled)
NATA exit NAT process
NAT Process Flow
Rx send interrupt
Rx triggers NAT
processing
NAT hit?
Yes
- 102 -
W90N740CD/W90N740CDG
No
No NAT processing