LPC1767FBD100,551 NXP Semiconductors, LPC1767FBD100,551 Datasheet - Page 197

• 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
Fig 23. Transmit Flow Control
MirrorCounter
device driver
(1/515 bit
slots)
transmit
register
receive
RMII
RMII
writes
10.17.9 Half-Duplex mode backpressure
0
MirrorCounter
PauseTimer
TxFlowCtl
transmission
normal
50
In this example, a frame is received while transmitting another frame (full duplex.) The
device driver detects that some buffer might overrun and enables the transmit flow control
by programming the PauseTimer and MirrorCounter fields of the FlowControlCounter
register, after which it enables the transmit flow control by setting the TxFlowControl bit in
the Command register.
As a response to the enabling of the flow control a pause control frame will be sent after
the currently transmitting frame has been transmitted. When the pause frame
transmission completes the internal mirror counter will start counting bit slots; as soon as
the counter reaches the value in the MirrorCounter field another pause frame is
transmitted. While counting the transmit data path will continue normal transmissions.
As soon as software disables transmit flow control a zero pause control frame is
transmitted to resume the receive process.
When in half-duplex mode, backpressure can be generated to stall receive packets by
sending continuous preamble that basically jams any other transmissions on the Ethernet
medium. When the Ethernet block operates in half duplex mode, asserting
the TxFlowControl bit in the Command register will result in applying continuous preamble
on the Ethernet wire, effectively blocking traffic from any other Ethernet station on the
same segment.
In half duplex mode, when the TxFlowControl bit goes high, continuous preamble is sent
until TxFlowControl is de-asserted. If the medium is idle, the Ethernet block begins
transmitting preamble, which raises carrier sense causing all other stations to defer. In the
event the transmitting of preamble causes a collision, the backpressure ‘rides through’ the
collision. The colliding station backs off and then defers to the backpressure. If during
backpressure, the user wishes to send a frame, the backpressure is interrupted, the frame
sent and then the backpressure resumed. If TxFlowControl is asserted for longer than
3.3 ms in 10 Mbps mode or 0.33 ms in 100 Mbps mode, backpressure will cease sending
preamble for several byte times to avoid the jabber limit.
normal receive
pause control
transmission
frame
100
All information provided in this document is subject to legal disclaimers.
150
normal transimisson
Rev. 2 — 19 August 2010
200
250
pause in effect
pause control
transmission
frame
300
TxFlowCtl
clear
350
Chapter 10: LPC17xx Ethernet
pause control
transmission
frame
400
UM10360
© NXP B.V. 2010. All rights reserved.
normal receive
450
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