The ISP1161A1 is a single-chip Universal Serial Bus (USB) Host Controller (HC) and Device Controller (DC). The Host Controller portion of the ISP1161A1 complies with Universal Serial Bus Specification Rev. 2.0, supporting data transfer at full-speed (12 Mbit/s) and low-speed (1.5 Mbit/s). The Device Controller portion of the ISP1161A1 also complies with Universal Serial Bus Specification Rev. 2.0, supporting data transfer at full-speed (12 Mbit/s). These two USB controllers, the HC and the DC, share the same microprocessor bus interface. They have the same data bus, but different I/O locations. They also have separate interrupt request output pins, separate DMA channels that include separate DMA request output pins and DMA acknowledge input pins. This makes it possible for a microprocessor to control both the USB HC and the USB DC at the same time. The ISP1161A1 provides two downstream ports for the USB HC and one upstream port for the USB DC. Each downstream port has an overcurrent (OC) detection input pin and power supply switching control output pin. The upstream port has a VBUS detection input pin.The ISP1161A1 also provides separate wake-up input pins and suspended status output pins for the USB HC and the USB DC, respectively. This makes power management flexible. The downstream ports for the HC can be connected with any USB compliant devices and hubs that have USB upstream ports. The upstream port for the DC can be connected to any USB compliant USB host and USB hubs that have USB downstream ports. The HC is adapted from the Open Host Controller Interface Specification for USB Release 1.0a, referred to as OHCI in the rest of this document. The DC is compliant with most USB device class specifications such as Imaging Class, Mass Storage Devices, Communication Devices, Printing Devices and Human Interface Devices.