LPC2468FET208,551 NXP Semiconductors, LPC2468FET208,551 Datasheet - Page 216

• Manufacturer Part Number: LPC2468FET208,551
• Description: IC ARM7 MCU FLASH 512K 208TFBGA
• Manufacturer: NXP Semiconductors
• Series: LPC2400r

Specifications of LPC2468FET208,551

• Program Memory Type: FLASH
• Program Memory Size: 512KB (512K x 8)
• Package / Case: 208-TFBGA
• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 72MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, Microwire, MMC, SPI, SSI, SSP, UART/USART, USB OTG
• Peripherals: Brown-out Detect/Reset, DMA, I²S, POR, PWM, WDT
• Number Of I /o: 160
• Ram Size: 98K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: LPC24
• Core: ARM7TDMI-S
• Data Bus Width: 16 bit, 32 bit
• Data Ram Size: 98 KB
• Interface Type: CAN/I2S/ISP/SSP/UART/USB
• Maximum Clock Frequency: 72 MHz
• Number Of Programmable I/os: 160
• Number Of Timers: 6
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: MDK-ARM, RL-ARM, ULINK2, IRD-LPC2468-DEV, SAB-TFBGA208, KSK-LPC2468-PL
• Development Tools By Supplier: OM10100
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 10-bit
• On-chip Dac: 1-ch x 10-bit
• Package: 208TFBGA
• Device Core: ARM7TDMI-S
• Family Name: LPC2000
• Maximum Speed: 72 MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 622-1025 - KIT DEV IND REF DESIGN LPC2468622-1024 - BOARD SCKT ADAPTER FOR TFBGA208568-4358 - DISPLAY QVGA TFT FOR OM10100568-4309 - BOARD EXTENSION LPCSTICK568-4308 - EVAL LPC-STICK WITH LPC2468MCB2400U - BOARD EVAL MCB2400 + ULINK2MCB2400 - BOARD EVAL FOR NXP LPC246X SER622-1005 - USB IN-CIRCUIT PROG ARM7 LPC2K
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 568-4262; 935283234551; LPC2468FET208-S

NXP Semiconductors
UM10237_4
User manual
5.4 Overview of DMA operation
5.5 Ethernet Packet
Descriptors, which are stored in memory, contain information about fragments of incoming
or outgoing Ethernet frames. A fragment may be an entire frame or a much smaller
amount of data. Each descriptor contains a pointer to a memory buffer that holds data
associated with a fragment, the size of the fragment buffer, and details of how the
fragment will be transmitted or received.
Descriptors are stored in arrays in memory, which are located by pointer registers in the
Ethernet block. Other registers determine the size of the arrays, point to the next
descriptor in each array that will be used by the DMA engine, and point to the next
descriptor in each array that will be used by the Ethernet device driver.
The DMA engine makes use of a Receive descriptor array and a Transmit descriptor array
in memory. All or part of an Ethernet frame may be contained in a memory buffer
associated with a descriptor. When transmitting, the transmit DMA engine uses as many
descriptors as needed (one or more) to obtain (gather) all of the parts of a frame, and
sends them out in sequence. When receiving, the receive DMA engine also uses as many
descriptors as needed (one or more) to find places to store (scatter) all of the data in the
received frame.
The base address registers for the descriptor array, registers indicating the number of
descriptor array entries, and descriptor array input/output pointers are contained in the
Ethernet block. The descriptor entries and all transmit and receive packet data are stored
in memory which is not a part of the Ethernet block. The descriptor entries tell where
related frame data is stored in memory, certain aspects of how the data is handled, and
the result status of each Ethernet transaction.
Hardware in the DMA engine controls how data incoming from the Ethernet MAC is saved
to memory, causes fragment related status to be saved, and advances the hardware
receive pointer for incoming data. Driver software must handle the disposition of received
data, changing of descriptor data addresses (to avoid unnecessary data movement), and
advancing the software receive pointer. The two pointers create a circular queue in the
descriptor array and allow both the DMA hardware and the driver software to know which
descriptors (if any) are available for their use, including whether the descriptor array is
empty or full.
Similarly, driver software must set up pointers to data that will be transmitted by the
Ethernet MAC, giving instructions for each fragment of data, and advancing the software
transmit pointer for outgoing data. Hardware in the DMA engine reads this information and
sends the data to the Ethernet MAC interface when possible, updating the status and
advancing the hardware transmit pointer.
Figure 11–27
illustrates the different fields in an Ethernet packet.
Rev. 04 — 26 August 2009
Chapter 11: LPC24XX Ethernet
UM10237
© NXP B.V. 2009. All rights reserved.
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