Semiconductor device

Abstract

According to one embodiment, a semiconductor device includes a device. The device includes a decoder, a generation circuit, a register, and a modifier. The decoder analyzes a command of a received packet. The generation circuit generates a unique device number in accordance with information in the packet. The register holds the generated unique device number. The modifier updates and outputs the packet. When a packet issued by a host is a command packet, among broadcast packets which return to the host through one or more devices, for determining the unique device number, the command packet includes parameters of an initial value and final value of device number.

What is claimed is: 
     
       1. A semiconductor device comprising a device, the device including:
 a decoder which analyzes a command of a received packet to determine processing specified by the packet;   a generation circuit which generates a unique device number in accordance with information in the packet;   a register which holds the generated unique device number; and   a modifier which updates and outputs the packet, wherein   when a packet issued by a host is a command packet, among broadcast packets which return to the host through one or more devices, for determining the unique device number, the command packet includes parameters of an initial value and final value of device number,   the device determines, based on the final value, whether the device has first received the command packet from the host for determining the unique device number,   the device,
 when the device determines that the device has first received the command packet from the host for determining the unique device number, 
 determines device number in accordance with the initial value of the received command packet, sets the determined device number to the register, updates the initial value and the final value in the command packet to the determined device number, and transmits the command packet to a next device or the host, wherein if the initial value is a predetermined value, the device number of the device is arbitrarily determined by the device, otherwise the device number of the device is determined by the host, 
 when the device determines that the device has not first received the command packet from the host for determining the unique device number, 
 calculates device number different from determined device number of another device by incrementing the final value in the received command packet, set the calculated device number to the register, updates the final value to the calculated device number without updating the initial value in the command packet, and transmits the command packet to a next device or the host, and 
   the updated initial value and the updated final value are set to the same fields as those of the initial value and the final value before updating.   
     
     
       2. A semiconductor device comprising a device, the device including:
 a decoder which analyzes a command of a received packet to determine processing specified by the packet;   a generation circuit which generates a unique device number in accordance with information in the packet;   a register which holds the generated unique device number; and   a modifier that updates and outputs the packet, wherein   when a packet issued by a host is a command packet, among broadcast packets which return to the host through one or more devices, for determining the unique device number, the command packet includes parameters of an initial value of device number and the number of devices,   the device,
 when the device determines that the device has first received the command packet from the host for determining the unique device number, 
 determines device number in accordance with the initial value of the received command packet, sets the determined device number to the register, updates the initial value and the number of devices in the command packet to the determined device number and “1”, respectively, and transmits the command packet to a next device or the host, wherein if the initial value is a predetermined value, the device number of the device is arbitrarily determined by the device, otherwise the device number of the device is determined by the host, 
 when the device determines that the device has not first received the command packet from the host for determining the unique device number, 
 calculates device number different from determined device number of another device by incrementing the number of devices in the received command packet, set the calculated device number to the register, updates the number of devices to incremented value without updating the initial value in the command packet, and transmits the command packet to a next device or the host, and 
   the updated initial value and the updated number of devices are set to the same fields as those of the initial value and the final value before updating.   
     
     
       3. The device according to  claim 2 , wherein the device number of the device which does not first receive the command packet from the host is equal to the value obtained by adding the initial value and the number of devices in the received command packet. 
     
     
       4. A host apparatus configured to connect to a plurality of devices, wherein the host apparatus
 issues a first packet in which an initial value and a final value of a device number are set to predetermined values to a first device,   receives a final packet in which the initial value and the final value are updated through all the devices from a final device, and   recognizes a number of the connected devices and the device numbers allocated to the devices from the updated initial value and final value in the final packet, wherein   if the host apparatus sets a predetermined value as the initial value, the device number of the first device is arbitrarily determined by the first device, otherwise the device number of the first device is determined by the host apparatus, and   the updated initial value and the updated final value are set to the same fields as those of the initial value and the final value before updating.   
     
     
       5. A host apparatus configured to connect to a plurality of devices, wherein the host apparatus
 issues a first packet in which an initial value of a device number and the number of the devices are set to predetermined values to a first device,   receives a final packet in which the initial value and the number of the devices are updated through all the devices from a final device,   recognizes the updated initial value in the final packet as a device number of the first device, and   calculates the device numbers of the plurality of devices based on the updated initial value and the number of devices in the final packet, wherein   if the host apparatus sets a predetermined value as the initial value, the device number of the first device is arbitrarily determined by the first device, otherwise the device number of the first device is determined by the host apparatus, and   the updated initial value and the updated number of devices are set to the same fields as those of the initial value and the number of devices before updating.   
     
     
       6. A device number setting method performed by an electric device including a device, the method comprising:
 analyzing information fields issued from a host to determine processing specified by the information fields including a command;   generating a unique device number in accordance with the information fields;   holding the generated unique device number in a register of the device;   updating the information fields; and   outputting the updated information fields to a next device or the host,   wherein   in a case when the command is a broadcast command which returns to the host through one or more devices, for determining the unique device number and the information fields further includes parameters of an initial value of device number and the number of devices,
 when the information fields are first received from the host for determining the unique device number,
 the generating includes:
 determining a device number in accordance with the initial value of device number; and 
 setting the determined device number to the register, and 
 
 the updating includes:
 updating the initial value of device number and the number of devices in the information fields to the determined device number and “1”, respectively, wherein if the initial value is a predetermined value, the device number of the device is arbitrarily determined by the device except for the predetermined value, otherwise the device number of the device is the predetermined value, and 
 
 
 when the information fields are not first received from the host for determining the unique device number,
 the generating includes:
 calculating the device number different from a determined device number of another device by incrementing the number of devices in the information; and 
 setting the generated device number to the register, and 
 
 the updating includes:
 updating the number of devices to the incremented value without updating the initial value in the information fields, and 
 
 
   the updated initial value and the updated number of devices are set to the same information fields as those of the initial value and the number of devices before updating.    
     
     
       7. The method according to claim 6, wherein the information fields are included in a packet which contains a packet header and a payload.  
     
     
       8. The method according to claim 7, wherein the command is assigned to the packet header and the initial value of device number and the number of devices are assigned to the payload.