The bus speed determines the rate at which bits are sent across the bus. There are currently four speeds at which wired USB operates: low-speed (1.5 Mbps), full-speed (12 Mbps), high-speed (480 Mbps), and SuperSpeed (5 Gbps). In order to determine the bus speed of a full-speed or low-speed device, the host must simply look at the idle state of the bus. Full-speed devices have a pull-up resistor on the D+ line, whereas low-speed devices have a pull-up resistor on the D- line. Therefore, if the D+ line is high when idle, then full-speed connectivity is established. If the D- line is high when idle, then low-speed connectivity is in effect. A full-speed device does not have to be capable of running at low-speed, and vice versa. A full-speed host or hub, however, must be capable of communicating with both full-speed and low-speed devices.
The SYNC field, which is a sequence of KJ pairs followed by 2 K's on the data lines, serves as a Start of Packet (SOP) marker and is used to synchronize the devices transceiver with that of the host. This SYNC field is 8 bits long for full/low-speed and 32 bits long for high speed.
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The EOP field varies depending on the bus speed. For low- or full-speed buses, the EOP consists of an SE0 for two bit times. For high-speed buses, because the bus is at SE0 when it is idle, a different method is used to indicate the end of the packet. For high-speed, the transmitter induces a bit stuff error to indicate the end of the packet. So if the line state before the EOP is J, the transmitter will send 8-bits of K. The exception to this is the high-speed SOF EOP, in which case the high-speed EOP is extended to 40-bits long. This is done for bus disconnect detection.
The PID is the first byte of valid data sent across the bus, and it encodes the packet type. The PID may be followed by anywhere from 0 to 1026 bytes, depending on the packet type. The PID byte is self-checking; in order for the PID to be valid, the last 4 bits must be a ones complement of the first 4 bits. If a received PID fails its check, the remainder of the packet will be ignored by the USB device.
The new Link Power Management addendum to the USB 2.0 Specification has expanded the number of PIDs through the use of the previously reserved PID, 0xF0. The extended token format is a two phase transaction that begins with a standard token packet that has the EXT PID. Following this packet is the extended token packet, which takes a similar form. It begins with an 8-bit SubPID and ends with a 5-bit CRC, however the 11 remaining bits in the middle will have different meaning depending on the type of SubPID.
Because all commnication takes place on only two wires, all devices must have a unique address to identify it on the bus. Slave devices have a predefined address, but the lower bits of the address can be assigned to allow for multiples of the same devices on the bus.
The benefits of adding this two cycle access are that Clause 45 is backwards compatible with Clause 2, allowing devices to interoperate with each other. Secondly, by creating a address frame, the register address space is increased from 5 bits to 16 bits, which allows an STA to access 65,536 different registers.
For each u16 written to data_in by the function, the lower 8-bits represent the value of a byte of data sent across the bus and bit 8 represents the ACK or NACK value for that byte. A 0 in bit 8 represents an ACK and a 1 in bit 8 represents a NACK. See Table 14 for constants that may be used as bit mask to access the appropriate fields in data_in.
Only bits [3:0] can be set in either of the input pin edge masks. Similarly, only bits [3:1] can be set in dig_out_match_pin_mask. Setting invalid bits will cause this function to return BG_CONFIG_ERROR.
When the match packet type is ERROR, the BeagleUsb2ErrorType value is actually used as a bitmask to test for various errors. The possible errors to test for are CRC errors, corrupted PIDs, jabber, and general PHY receive errors. By masking these bits together on an ERROR packet type, multiple error conditions can be matched with a single match unit.
The bit_timing array will be filled with the duration of each of the bits in the packet array. The duration of each bit is provided in counts of a 480 MHz clock, corresponding to approximately a 2 ns resolution. Those bits that are followed by a bit-stuff will have a duration that is twice as long as a normal bit time for that speed.
When the match packet type is ERROR, the BeagleUsb3ErrorType value is actually used as a bitmask to test for various bit corruptions. The possible errors to test for are CRC errors, framing errors (a single corrupted symbol in the framing), and unknown packets. By masking these bits together on an ERROR packet type, multiple error conditions can be matched with a single match unit.
(5) For the sake of clarity, bits BG_USB_EDGE_RISING and BG_USB_EDGE_FALLING must both be set in the event edge_mask, as the analyzer will always match on either edge for these event types
Estoy intentando por linea de comandos desintalar un pendrive, utilizando devcon, la pc que utilizo es windows 7 64 bit, el comando que corro es este: devcon.exe remove "@USB\VID_13FE&PID_3D00&REV_0100"
The drivers provided on this page are for Virtual Usb vusbbus, and most of them are for Windows operating system. Before downloading the driver, please confirm the version number of the operating system installed on the computer where the driver will be installed. If the system version number does not meet the driver requirements, it may cause some unexpected problems. In the case of determining the operating system version number, it is recommended to download the 5-star driver first. 2ff7e9595c
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