Patent ID: 7430660

Claim:
A data transmission method used between an image providing device and a target device which are connected by a serial bus, the method comprising the steps of: setting, in communication between the image providing device and the target device, a PULL method as a data transfer method to pull data from the image providing device based on control of the target device, in accordance with a first request issued by the image providing device; controlling readout of the data from the image providing device in accordance with a second request issued by the target device when the PULL method is set; locking a data resource of the target device on the image providing device before said setting step; transferring the data between the image providing device and the target device, wherein the target device does not accept control from any device except for the image providing device in said transferring step; and releasing the lock of the data resource of the target device in accordance with a third request issued by the image providing device after said transferring step.