AT89C5131-RDTIL datasheet(115/176 Pages) ATMEL

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AT89C5131

4136B–USB–09/03

USB Device Firmware

Upgrade (DFU)

The USB Device Firmware Update (DFU) protocol can be used to upgrade the on-chip

Flash memory of the AT89C5131. This allows the implementation of product enhance-

ments and patches to devices that are already in the field. Two different configurations

and descriptor sets are used to support DFU functions. The Run-Time configuration co-

exists with the usual functions of the device, which may be USB Mass Storage for the

AT89C5131. It is used to initiate DFU from the normal operating mode. The DFU config-

uration is used to perform the firmware update after device re-configuration and USB

reset. It excludes any other function. Only the default control pipe (endpoint 0) is used to

support DFU services in both configurations.

The only possible value for the wMaxPacketSize in the DFU configuration is 32 bytes,

which is the size of the FIFO implemented for endpoint 0.

Description

The USB device controller provides the hardware that the AT89C5131 needs to inter-

face a USB link to a data flow stored in a double port memory (DPRAM).

The USB controller requires a 48 MHz ±0.25% reference clock, which is the output of

the AT89C5131 PLL (see Section “PLL”, page 20) divided by a clock prescaler. This

clock is used to generate a 12 MHz Full-speed bit clock from the received USB differen-

tial data and to transmit data according to full speed USB device tolerance. Clock

recovery is done by a Digital Phase Locked Loop (DPLL) block, which is compliant with

the jitter specification of the USB bus.

The Serial Interface Engine (SIE) block performs NRZI encoding and decoding, bit stuff-

ing, CRC generation and checking, and the serial-parallel data conversion.

The Universal Function Interface (UFI) realizes the interface between the data flow and

the Dual Port RAM.

Figure 53. USB Device Controller Block Diagram

SIE

DPLL

USB

D+/D-

Buffer

UFI

12 MHz

48 MHz +/- 0.25%

D+

Up to 48 MHz

UC_sysclk

C51

Microcontroller

Interface

D-

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