USB in a Nut. Shell - Chapter 5. All USB devices have a hierarchy of descriptors which describe to the host information such as what the device is. USB it supports, how many ways it can be configured, the number of endpoints and. The more common USB descriptors are. USB devices can only have one device descriptor. The device descriptor includes information such as what USB. Product and Vendor IDs used to load the appropriate drivers and the number. Revision 1.1 March 2013 NC-SI Overview and Performance Understanding the DMTF Standard Manageability Interface Intel Synchronous Serial Interface (SSI) is a widely used serial interface standard for industrial applications between a master (e.g. Set Bandwidth Serial Interface GaramThe number of configurations indicate how many configuration. When a device is enumerated, the host. It can only enable one. Each configuration could be powered in the. However it should. For example you could have a multi- function fax/scanner/printer. Interface descriptor one could describe the endpoints of the fax function, Interface descriptor. Interface descriptor three the printer function. Unlike the configuration. A device could have. For example we could have a device. Interface one has b. Interface. Number set to. Alternative. Setting of zero. We could then throw in another descriptor. Interface. Number set to one indicating it is the second interface, but this time. Alternative. Setting to one, indicating this interface descriptor can be an. However during operation the host can send a Set. Interface request directed to that. Interface one with a alternative setting of one to enable the other interface descriptor. Endpoint zero, the default control endpoint is always assumed to be a control. If they are not. used, any string index fields of descriptors must be set to zero indicating there. String Index 0 should return a list. A list of USB Language IDs can be found in. Universal Serial Bus Language. Identifiers (LANGIDs) version 1. Number. Size of Descriptor in Bytes. Descriptor. Type. Constant. String Descriptor (0x. LANGID. 0x. 04. 09 English - United States). LANGID. 0x. 0c. 09 English - Australian). LANGID. 0x. 04. 07 German - Standard). The above String Descriptor shows the format of String Descriptor Zero. The host should read this. If a language is supported, it can then. ID in the w. Index field of a. Get Descriptor(String) request. Synchronous Serial Interface - Wikipedia, the free encyclopedia. Synchronous Serial Interface (SSI) is a widely used serial interface standard for industrial applications between a master (e. SSI is based on RS- 4. SSI was originally developed by Max Stegmann GMBH in 1. It was formerly covered by the German patent DE 3. It is very suitable for applications demanding reliability and robustness in measurements under varying industrial environments. It is different from the Serial Peripheral Interface Bus (SPI): A SSI is differential, simplex, non- multiplexed, and relies on a time- out to frame the data. A SPI is single- ended, duplex, multiplex and uses a select- line to frame the data. However, SPI peripherals on microcontrollers can implement SSI with external differential driver- ICs and program- controlled timing. Introduction. Synchronous data transmission is one in which the data is transmitted by synchronizing the transmission at the receiving and sending ends using a common clock signal. Since start and stop bits are not present, this allows better use of data transmission bandwidth for more message bits and makes the whole transmission process simpler and easier. The clock needs its own bandwidth and should be included when determining the total bandwidth required for communication between the two devices. PLC, Microcontroller) to a slave (e. The master controls the clock sequence and the slave transmits the current data/value through a shift register. When invoked by the master, the data is clocked out from the shift register. The master and slave are synchronized by the common clock of the controller. The CLOCK and DATA signals are transmitted according to RS- 4. RS- 4. 22, also known as ANSI/TIA/EIA- 4. B, is a technical standard that specifies the electrical characteristics of the balanced voltage digital interface circuit. Data is transmitted using balanced or differential signalling i. The DATA output of the sensor is driven by an RS- 4. Differential signalling improves the resistance to electromagnetic interference (EMI), hence making it a reliable communication channel over long transmission lengths and harsh external environments. SSI design. It consists of 2 pairs of wires, one for transmitting the clock signals from the master and the other for transmitting the data from the slave. The clock sequences are triggered by the master when need arises. Different clock frequencies can be used ranging from 1. Hz to 2 MHz and the number of clock pulses depends on the number of data bits to be transmitted. The simplest SSI slave interface uses a retriggerable monostable multivibrator (monoflop) to freeze the current value of the sensor. The current frozen values of the slave are stored in Shift registers. These values are clocked out sequentially when initiated by the controller. The design is being revolutionized with the integration of microcontrollers, FPGAs and ASICs into the interface. The data format is designed in such a way to ensure proper communication of data. The protocol for the data transmission is based on three different subsequent parts (Leading- . The main significance of this type of format is to ensure the proper working of the interface and hence secure data transmission free from any hardware or software errors. In idle state the CLOCK is on high level and also the sensor output is on high level, so that it can be used for detecting any broken wire contacts. This helps in observing the proper working condition of the interface. After n- CLOCK pulses (rising edges) the data is completely transmitted. With the next CLOCK pulse (rising edge n+1) the sensor output goes to low level which can be used to detect a short circuit in the cable. If it is high even after n+1 rising edges then it means that the interface has a short circuit. Readings from multiple slaves (up to three) can be enabled at the same time by connecting them to a common clock. How to configure Router Serial Interfaces, DTE (Data Terminal Equipment) and DCE (Data Communications Equipment)When connecting a serial cable to the serial interface of the router, clocking is provided by an external device, such as a CSU/DSU device. A CSU/DSU (Channel Service Unit/Data Service Unit) is a digital- interface device used to connect a router to a digital circuit. The router is the DTE (Data Terminal Equipment) and the external device is the DCE (Data Communications Equipment), where the DCE provides the clocking. However, in some cases we might connect two routers back- to- back using the routers’ serial interfaces (Example: Inside the router labs). The cable decides which end to be DCE or DTE and it is usually marked on the cable. The picture below shows back to back cable. If is not marked, we can use the Cisco IOS show command . Since clocking is required to enable the interface, one of the two routers should function as DCE and should provide clocking. This can be done by using the . To find the possible clock rate values, get the command help by using a question mark after the ? You can find the possible values by using help. This is used by certain routing protocols, such as IGRP, OSPF, and EIGRP, when making routing decisions. However, on synchronous serial interfaces, the bandwidth defaults to 1,5. Kbps and this is not related with the clock rate set. To change the bandwidth value for an interface, use the bandwidth Interface Subconfiguration mode command. Router(config)# interface s. Router(config- if)#bandwidth 6.
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