US Patent 7340554 USB host controller with DMA capability

An embedded host controller, for use in a USB system comprising a processor and an associated system memory, comprises a DMA controller, and the host controller is adapted such that, in order to retrieve data from the associated system memory, a starting address and block length are sent to the DMA controller, and the DMA controller is adapted such that, on receipt of a starting address and block length sent from the host controller, it retrieves the indicated data from the associated system memory. This has the advantage that the embedded host controller can be used with different host microprocessors, without assuming that PCI functionality is available.