User's Manual

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1.2.1 USB 2.0 Device Interface Description
Table shows the signal mapping between the AW-CB250NF and the USB Specification, Revision 2.0.
1.2.2 USB 2.0 Device Functional Description
The device controller uses internal Scatter/Gather DMA engine to transfer the transmit packet from internal SRAM
to USB and the receive packet from USB to internal SRAM. The Device IN Endpoint DMA (DIEPDMAn) and Device
OUT Endpoint DMA (DOEPDMAn) registers are used by the DMA engine to access the base descriptor. The
application is interrupted after the programmed transfer size extracted from the descriptors is transmitted or
received. By using registers, interrupts, and special data structures, the device controller can communicate with the
device controller driver (application/software) about bus states, host request, and data transfer status. The device
controller driver also has all of the routines to respond to the device framework commands issued by a USB host,
so it controls the attachment, configuration, operation, and detachment of the device.
1.3 High-Speed UART Interface
The AW-CB250NF supports a high-speed Universal Asynchronous Receiver/Transmitter (UART) interface,
compliant to the industry standard 16550 specification. High-speed baud rates are supported to provide the
physical transport between the device and the host for exchanging Bluetooth data. Table shows the rates
supported.
The UART interface features include:
FIFO mode permanently selected for transmit and receive operations
Two pins for transmit and receive operations
Two flow control pins
Interrupt triggers for low-power, high throughput operation
The UART interface operation includes:
Upload boot code to the internal CPU (for debug purposes)