In The Data Stage of a USB 2.0 Control Read Transfer
Posted by Parkzone Corsair in USB on February 21st, 2010
USB 2.0 device doesn’t return an expected handshake packet during a control transfer, the host retries. On receiving no response after a (typical) total of three tries, the host notifies the software that requested the transfer and stops communicating with the endpoint until the problem is resolved.
The two retries include only those sent in response to no handshake at all. A NAK triggers a retry but doesn’t increment the error count.Control transfers use data toggles (USB 2.0) or Sequence Numbers (Super- Speed) to protect against lost data. In the Data stage of a USB 2.0 Control read transfer, on receiving the data from the device, the host normally returns ACK and then sends an OUT token packet to begin the Status stage. If the device for any reason doesn’t see the ACK returned after the transfer’s final data packet, the device must interpret a received OUT token packet as evidence that the Status stage has begun.
Devices must accept all error-free Setup packets. If a new Setup packet arrives before a previous control transfer completes, the device must abandon the previous transfer and start the new one.
A USB 2.0 device has these responsibilities for transfers on a control endpoint:
- Send ACK in response to every Setup packet received without error.
- For supported control write requests, send ACK in response to received data in the Data stage (if present) and return a ZLP in the Status stage.
- For supported control read requests, send data in response to IN token packets in the Data stage and ACK the received ZLP in the Status stage.
- For unsupported requests, return STALL in the Data or Status stage.
Protect your Loyal Companion
Posted by Parkzone Corsair in Business on February 18th, 2010
Your truck is the only one which accompanies you in doing your job. You must treasure it very much. You always want the car to stay at its current condition, powerful and tough. It is because you cannot work without it. And, if you don’t work, you will have no money for your living.
Thus, you need to really take care of your car. You should not let your car suffer because of your carelessness. Since the area where you are living now is a windy area, it is best to give your car a bug shield. It will protect the engine from unwanted debris and bug which may lead to a malfunction. You should also clean the tires and the wheels from the mud and elements which may make your truck hard to move. So, you should always provide the truck mud flaps inside your garage. Then, if you do not want your truck to carry unnecessary item on its back, cover it with bakflip tonneau. The cover is designed for heavy duty job that it will fully protect your truck’s bed.
To get all of those truck accessories, Realtruck.com is your best destination. The website can give you everything that your car needs and it will never make you break your wallet.
Rugs for Your Computer Room
Posted by Parkzone Corsair in Business on February 15th, 2010
In the public places like office, internet café or even private residences computer is usually used for a long time either just to browse the internet or write report or assignment that should be submitted at the next day. Because usually people use computer for a long time, you as the internet café owner, boss of a certain business or even household mother should give special treatment to the room where the computers put. The reason is to make whoever who sit in front of the computer feel comfortable and can stay for hours.
Besides to make the user of the computer feel comfortable, carpet or area rugs can also make the computer feel happy because by covering the floor with carpet, the room will be cleaner than before and there will be no more dirt, dust or other small things that can make the computer dirty. To keep the computer clean of course will extend the useful time of the computer because its CPU is free from the dust. In choosing the rugs for your computer room, you have to match with the size or dimension of your room so that the entire floor surface can be covered with the carpet or rugs.
You don’t have to buy expensive rugs or carpet to make your computer room clean, cheap rugs and carpet will do as long as the size is correct. Nowadays, you can easily buy carpets or rugs in many carpet stores scattered across the town and they usually sell many choices of carpet which you can freely choose. To make you easier in choosing and buying carpets there are also available online carpet shops which will deliver your carpet or rugs of your choice after you make the payment so you don’t have to worry about how you will bring the carpet home after you buy it.
