Target device in serial communication and external device connected to target device
A target device for which size reduction is required, and that has a terminal compatible with the series B version, and communicates with an accessory device through a USB connector. The target device includes a universal serial bus (USB) transceiver, and a storage section for holding data to be transmitted through the USB transceiver. The target device sends a flow control signal concerning the transmission of the data held in said storage section to said external device connected thereto through said USB transceiver.
1 . A device system having a target device and at least one external device, wherein said target device and said external device have universal serial bus (USB) transceivers, respectively, and are interconnected so as to be communicable with each other through said USB transceivers, said target device includes a storage section for holding data to be transmitted through said USB transceiver, and sends a flow control signal concerning the transmission of the data held in said storage section to said external device connected thereto through said USB transceiver, and said external device receives said flow control signal concerning the data transmission from said target device connected thereto through said USB transceiver, and controls the transmission operation of data between said external device itself and said external device according to said flow control signal.
2 . A target device having a USB transceiver and a storage section holding data being transmitted via USB transceiver, wherein said target device sends a flow control signal concerning the transmission of the data held in said storage section to said external device connected thereto through said USB transceiver.
3 . The target device according to claim 2 , further comprising a control section for executing a process defined by a bus driver program module for executing control of said USB transceiver, a common processing program module for defining a process common to various types of external devices connected thereto through said USB transceiver, and a proper program module for defining processes proper to said external devices connected thereto through said USB transceiver by communicating with at least one of said common processing program module and said bus driver program module.
4 . The target device according to claim 2 , wherein before communication based on the USB standard is started, said target device transmits out-of-standard certification information concerning an authentication not prescribed in the USB standard, and applies a predetermined authentication process based on said out-of-standard certification information to an external device connected thereto through said USB transceiver.
5 . The target device according to claim 2 , wherein said flow control signal is a signal for instructing the start and stop of the transmission of data.
6 . An external device having a USB transceiver, wherein said external device receives a flow control signal concerning the transmission of data from a target device connected thereto through said USB transceiver, and controls the transmission operation of data to and from said target device according to said flow control signal.
7 . A communication control method in a device system having a target device and an external device in which said target device and said external device have universal serial bus (USB) transceivers, respectively, and are interconnected so as to be communicable with each other through of said USB transceivers, wherein said target device holds data to be transmitted through said USB transceiver, and sends a flow control signal concerning the transmission of the data held to said external device connected thereto through said USB transceiver, and said external device receives said flow control signal concerning the data transmission from said target device connected thereto through said USB transceiver, and controls the transmission operation of data between said external device itself and said external device according to said flow control signal.