LPC1767FBD100,551 NXP Semiconductors, LPC1767FBD100,551 Datasheet - Page 194

• Manufacturer Part Number: LPC1767FBD100,551
• Description: IC ARM CORTEX MCU 512K 100-LQFP
• Manufacturer: NXP Semiconductors
• Series: LPC17xxr

Specifications of LPC1767FBD100,551

• Core Processor: ARM® Cortex-M3™
• Core Size: 32-Bit
• Speed: 100MHz
• Connectivity: Ethernet, I²C, IrDA, Microwire, SPI, SSI, UART/USART
• Peripherals: Brown-out Detect/Reset, DMA, I²S, Motor Control PWM, POR, PWM, WDT
• Number Of I /o: 70
• Program Memory Size: 512KB (512K x 8)
• Program Memory Type: FLASH
• Ram Size: 64K x 8
• Voltage - Supply (vcc/vdd): 2.4 V ~ 3.6 V
• Data Converters: A/D 8x12b, D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LQFP
• Processor Series: LPC17
• Core: ARM Cortex M3
• 3rd Party Development Tools: MDK-ARM, RL-ARM, ULINK2, MCB1760, MCB1760U, MCB1760UME
• For Use With: 622-1005 - USB IN-CIRCUIT PROG ARM7 LPC2K
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details
• Other names: 568-4967; 935289808551

NXP Semiconductors
UM10360
User manual
10.17.5 Transmission retry
10.17.6 Status hash CRC calculations
Each four pairs of bits transferred on the RMII interface are transferred as a byte on the
data write interface after being delayed by 128 or 136 cycles for filtering by the receive
filter and buffer modules. The Ethernet block removes preamble, frame start delimiter, and
CRC from the data and checks the CRC. To limit the buffer NoDescriptor error probability,
three descriptors are buffered. The value of the RxProduceIndex is only updated after
status information has been committed to memory, which is checked by an internal tag
protocol in the memory interface. The software device driver will process the receive data,
after which the device driver will update the RxConsumeIndex.
If a collision on the Ethernet occurs, it usually takes place during the collision window
spanning the first 64 bytes of a frame. If collision is detected, the Ethernet block will retry
the transmission. For this purpose, the first 64 bytes of a frame are buffered, so that this
data can be used during the retry. A transmission retry within the first 64 bytes in a frame
is fully transparent to the application and device driver software.
When a collision occurs outside of the 64 byte collision window, a LateCollision error is
triggered, and the transmission is aborted. After a LateCollision error, the remaining data
in the transmit frame will be discarded. The Ethernet block will set the Error and
LateCollision bits in the frame’s status fields. The TxError bit in the IntStatus register will
be set. If the corresponding bit in the IntEnable register is set, the TxError bit in the
IntStatus register will be propagated to the CPU (via the NVIC). The device driver software
should catch the interrupt and take appropriate actions.
The ‘RETRANSMISSION MAXIMUM’ field of the CLRT register can be used to configure
the maximum number of retries before aborting the transmission.
For each received frame, the Ethernet block is able to detect the destination address and
source address and from them calculate the corresponding hash CRCs. To perform the
computation, the Ethernet block features two internal blocks: one is a controller
synchronized with the beginning and the end of each frame, the second block is the CRC
calculator.
When a new frame is detected, internal signaling notifies the controller.The controller
starts counting the incoming bytes of the frame, which correspond to the destination
address bytes. When the sixth (and last) byte is counted, the controller notifies the
calculator to store the corresponding 32-bit CRC into a first inner register. Then the
controller repeats counting the next incoming bytes, in order to get synchronized with the
source address. When the last byte of the source address is encountered, the controller
again notifies the CRC calculator, which freezes until the next new frame. When the
calculator receives this second notification, it stores the present 32-bit CRC into a second
inner register. Then the CRCs remain frozen in their own registers until new notifications
arise.
The destination address and source address hash CRCs being written in the
StatusHashCRC word are the nine most significant bits of the 32-bit CRCs as calculated
by the CRC calculator.
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 19 August 2010
Chapter 10: LPC17xx Ethernet
UM10360
© NXP B.V. 2010. All rights reserved.
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