LPC2460FET208,551 NXP Semiconductors, LPC2460FET208,551 Datasheet - Page 279

• Manufacturer Part Number: LPC2460FET208,551
• Description: IC ARM7 MCU ROMLESS 208TFBGA
• Manufacturer: NXP Semiconductors
• Series: LPC2400r

Specifications of LPC2460FET208,551

• Program Memory Type: ROMless
• 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: 96K 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/I2C/I2S/SPI/SSP/UART/USB
• Maximum Clock Frequency: 72 MHz
• Number Of Programmable I/os: 160
• Number Of Timers: 4
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: MDK-ARM, RL-ARM, ULINK2, MCB2460, MCB2460U
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 10-bit
• On-chip Dac: 1-ch x 10-bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: MCB2400U - BOARD EVAL MCB2400 + ULINK2MCB2400 - BOARD EVAL FOR NXP LPC246X SER
• Eeprom Size: -
• Program Memory Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 568-4260; 935283232551; LPC2460FET208-S

NXP Semiconductors
UM10237_4
User manual
9.23.2 Types of CPU access
9.23.3 Overall bandwidth
9.24 CRC calculation
This gives a total rate of 30.5 Mbps for the traffic generated by the Ethernet DMA function.
This gives a total rate of 36 Mbps for the traffic generated by the Ethernet DMA function.
Overall traffic on the AHB is the sum of DMA access rates and CPU access rates, which
comes to approximately 66.5 MB/s.
The peak bandwidth requirement can be somewhat higher due to the use of small
memory buffers, in order to hold often used addresses (e.g. the station address) for
example. Driver software can determine how to build frames in an efficient manner that
does not overutilize the AHB.
The bandwidth available on the AHB bus depends on the system clock frequency. As an
example, assume that the system clock is set at 60 MHz. All or nearly all of bus accesses
related to the Ethernet will be word transfers. The raw AHB bandwidth can be
approximated as 4 bytes per two system clocks, which equals 2 times the system clock
rate. With a 60 MHz system clock, the bandwidth is 120 MB/s, giving about 55% utilization
for Ethernet traffic during simultaneous transmit and receive operations.
The calculation is used for several purposes:
The C pseudocode function below calculates the CRC on a frame taking the frame
(without FCS) and the number of bytes in the frame as arguments. The function returns
the CRC as a 32 bit integer.
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•
•
•
•
– Data to be received in an Ethernet frame, the size is variable.
– Basic Ethernet rate = 12.5 Mbps.
Accesses that mirror each of the DMA access types:
– All or part of status values must be read, and all or part of descriptors need to be
– This gives roughly the same or slightly lower rate as the combined DMA functions,
Access to registers in the Ethernet block:
– The CPU must read the RxProduceIndex, TxConsumeIndex, and IntStatus
– 7 word read/writes once every 64 bytes (16 words) of transmitted and received
– This gives 7/16 of the data rate, which = 5.4688 Mbps.
Generation the FCS at the end of the Ethernet frame.
Generation of the hash table index for the hash table filtering.
Generation of the destination and source address hash CRCs.
written after each use, transmitted data must be stored in the memory by the CPU,
and eventually received data must be retrieved from the memory by the CPU.
which = 30.5 Mbps.
registers, and both read and write the RxConsumeIndex and TxProduceIndex
registers.
data.
Rev. 04 — 26 August 2009
Chapter 11: LPC24XX Ethernet
UM10237
© NXP B.V. 2009. All rights reserved.
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