TAS1020BPFBR Datasheet, PDF (17/118 Pages) Texas Instruments – USB Streaming Controller

TAS1020B
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SLES025B – JANUARY 2002 – REVISED MAY 2011
2.1.6 USB Buffer Manager (UBM)
The USB buffer manager provides the control logic that interfaces the SIE to the USB endpoint buffers.
One of the major functions of the UBM is to decode the USB function address to determine if the host PC
is addressing the TAS1020B device USB peripheral function. In addition, the endpoint address field and
direction signal are decoded to determine which particular USB endpoint is being addressed. Based on
the direction of the USB transaction and the endpoint number, the UBM will either write or read the data
packet to or from the appropriate USB endpoint data buffer.
2.1.7 USB Frame Timer
The USB frame timer logic receives the start of frame (SOF) packet from the host PC each USB frame.
Each frame, the logic stores the 11-bit frame number value from the SOF packet in a register and asserts
the internal SOF signal. The frame number register can be read by the MCU and the value can be used
as a time stamp. For USB frames in which the SOF packet is corrupted or not received, the frame timer
logic will generate a pseudo start of frame (PSOF) signal and increment the frame number register.
2.1.8 USB Suspend and Resume Logic
The USB suspend and resume logic detects suspend and resume conditions on the USB. This logic also
provides the internal signals used to control the TAS1020B device when these conditions occur. The
capability to resume operation from a suspend condition with a locally generated remote wake-up event is
also provided.
2.1.9 MCU Core
The TAS1020B uses an 8-bit microcontroller core that is based on the industry standard 8052. The MCU
is software compatible with the 8052, 8032, 80C52, 80C53, and 87C52 MCUs. The 8052 MCU is the
processing core of the TAS1020B and handles all USB control, interrupt and bulk endpoint transfers. Bulk
out end-point transfers can also be handled by one of the two DMA channels.
2.1.10 MCU Memory
In accordance with the industry standard 8052, the TAS1020B MCU memory is organized into program
memory, external data memory and internal data memory. A boot ROM program is used to download the
application code to a 6K byte RAM that is mapped to the program memory space. The external data
memory includes the USB endpoint configuration blocks, USB data buffers, and memory mapped
registers. The total external data memory space available is 1.5K bytes. A total of 256 bytes are provided
for the internal data memory.
2.1.11 USB Endpoint Configuration Blocks and Buffer Space
The USB endpoint configuration blocks are used by the MCU to configure and operate the required USB
endpoints for a particular application. In addition to the control end-point, the TAS1020B supports a total of
seven IN endpoints and seven OUT endpoints. A set of six bytes is provided for each endpoint to specify
the endpoint type, buffer address, buffer size, and data packet byte count.
The USB endpoint buffer configuration blocks and buffer space provided totals 1440 bytes. The buffer
space to be used by a particular endpoint is fully configurable by the MCU for a particular application.
Therefore, the MCU can configure each buffer based on the total number of endpoints to be used, the
maximum packet size to be used for each endpoint, and the selection of single or double buffering.
2.1.12 DMA Controller
Two DMA channels are provided to support the streaming of data for USB isochronous IN endpoints,
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