LPC1837FET256,551 NXP Semiconductors, LPC1837FET256,551 Datasheet - Page 415

• Manufacturer Part Number: LPC1837FET256,551
• Description: Microcontrollers (MCU) 32BIT ARM CORTEX-M3 MCU 136KB SRAM
• Manufacturer: NXP Semiconductors
• Series: LPC18xxr

Specifications of LPC1837FET256,551

• Core: ARM Cortex M3
• Core Processor: ARM® Cortex-M3™
• Core Size: 32-Bit
• Speed: 150MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, Microwire, SD/MMC, SPI, SSI, SSP, UART/USART, USB OTG
• Peripherals: Brown-out Detect/Reset, DMA, I²S, Motor Control PWM, POR, PWM, WDT
• Number Of I /o: 80
• Program Memory Size: 1MB (1M x 8)
• Program Memory Type: FLASH
• Eeprom Size: -
• Ram Size: 136K x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 3.6 V
• Data Converters: A/D 16x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 256-LBGA
• Lead Free Status / Rohs Status: Details
• Other names: 935293795551

NXP Semiconductors
<Document ID>
User manual
20.10.3 Bus reset
It is the responsibility of the DCD to maintain a state variable to differentiate between the
DefaultFS/HS state and the Address/Configured states. Change of state from Default to
Address and the configured states is part of the enumeration process described in the
device framework section of the USB 2.0 Specification.
As a result of entering the Address state, the device address register (DEVICEADDR)
must be programmed by the DCD.
Entry into the Configured indicates that all endpoints to be used in the operation of the
device have been properly initialized by programming the ENDPTCTRLx registers and
initializing the associated queue heads.
A bus reset is used by the host to initialize downstream devices. When a bus reset is
detected, the device controller will renegotiate its attachment speed, reset the device
address to 0, and notify the DCD by interrupt (assuming the USB Reset Interrupt Enable
is set). After a reset is received, all endpoints (except endpoint 0) are disabled and any
primed transactions will be cancelled by the device controller. The concept of priming will
be clarified below, but the DCD must perform the following tasks when a reset is received:
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Clear all setup token semaphores by reading the ENDPTSETUPSTAT register and
writing the same value back to the ENDPTSETUPSTAT register.
Clear all the endpoint complete status bits by reading the ENDPTCOMPLETE register
and writing the same value back to the ENDPTCOMPLETE register.
Cancel all primed status by waiting until all bits in the ENDPTPRIME are 0 and then
writing 0xFFFFFFFF to ENDPTFLUSH.
Read the reset bit in the PORTSCx register and make sure that it is still active. A USB
reset will occur for a minimum of 3 ms and the DCD must reach this point in the reset
cleanup before end of the reset occurs, otherwise a hardware reset of the device
controller is recommended (rare).
Remark: A hardware reset can be performed by writing a one to the device controller
reset bit in the USBCMD reset. Note: a hardware reset will cause the device to detach
from the bus by clearing the Run/Stop bit. Thus, the DCD must completely re-initialize
the device controller after a hardware reset.
Free all allocated dTDs because they will no longer be executed by the device
controller. If this is the first time the DCD is processing a USB reset event, then it is
likely that no dTDs have been allocated. At this time, the DCD may release control
back to the OS because no further changes to the device controller are permitted until
a Port Change Detect is indicated.
After a Port Change Detect, the device has reached the default state and the DCD
can read the PORTSCx to determine if the device is operating in FS or HS mode. At
this time, the device controller has reached normal operating mode and DCD can
begin enumeration according to the USB2.0 specification Chapter 9 - Device
Framework.
Remark: The device DCD may use the FS/HS mode information to determine the
bandwidth mode of the device.
All information provided in this document is subject to legal disclaimers.
Rev. 00.13 — 20 July 2011
Chapter 20: LPC18xx USB0 Host/Device/OTG controller
UM10430
© NXP B.V. 2011. All rights reserved.
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