Cypress Semiconductor FX2LP Instrukcja Użytkownika Pobierz pdf (Strona 4)

CY7C68013A/CY7C68014A

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Document #: 38-08032 Rev. *K Page 4 of 60

3.5 USB Boot Methods

During the power-up sequence, internal logic checks the I

port for the connection of an EEPROM whose first byte is

either 0xC0 or 0xC2. If found, it uses the VID/PID/DID values

in the EEPROM in place of the internally stored values (0xC0),

or it boot-loads the EEPROM contents into internal RAM

(0xC2). If no EEPROM is detected, FX2LP enumerates using

internally stored descriptors. The default ID values for FX2LP

are VID/PID/DID (0x04B4, 0x8613, 0xAxxx where xxx = Chip

revision).

[2]

3.6 ReNumeration™

Because the FX2LP’s configuration is soft, one chip can take

on the identities of multiple distinct USB devices.

When first plugged into USB, the FX2LP enumerates automat-

ically and downloads firmware and USB descriptor tables over

the USB cable. Next, the FX2LP enumerates again, this time

as a device defined by the downloaded information. This

patented two-step process, called ReNumeration™, happens

instantly when the device is plugged in, with no hint that the

initial download step has occurred.

Two control bits in the USBCS (USB Control and Status)

RENUM. To simulate a USB disconnect, the firmware sets

DISCON to 1. To reconnect, the firmware clears DISCON to 0.

Before reconnecting, the firmware sets or clears the RENUM

bit to indicate whether the firmware or the Default USB Device

will handle device requests over endpoint zero: if RENUM = 0,

the Default USB Device will handle device requests; if RENUM

= 1, the firmware will.

3.7 Bus-powered Applications

The FX2LP fully supports bus-powered designs by enumer-

ating with less than 100 mA as required by the USB 2.0 speci-

fication.

3.8 Interrupt System

3.8.1 INT2 Interrupt Request and Enable Registers

FX2LP implements an autovector feature for INT2 and INT4.

There are 27 INT2 (USB) vectors, and 14 INT4 (FIFO/GPIF)

vectors. See EZ-USB Technical Reference Manual (TRM) for

more details.

3.8.2 USB-Interrupt Autovectors

The main USB interrupt is shared by 27 interrupt sources. To

save the code and processing time that normally would be

required to identify the individual USB interrupt source, the

FX2LP provides a second level of interrupt vectoring, called

Autovectoring. When a USB interrupt is asserted, the FX2LP

pushes the program counter onto its stack then jumps to

address 0x0043, where it expects to find a “jump” instruction

to the USB Interrupt service routine.

Table 3-1. Special Function Registers

x8x 9x Ax Bx CxDxExFx

IOA IOB IOC IOD SCON1 PSW ACC B

1SP EXIF INT2CLR IOE SBUF1

2DPL0 MPAGE INT4CLR OEA

3DPH0

OEB

4 DPL1 OEC

5 DPH1 OED

6 DPS OEE

7PCON

8 TCON SCON0 IE IP T2CON EICON EIE EIP

9 TMOD SBUF0

ATL0AUTOPTRH1 EP2468STAT EP01STAT RCAP2L

BTL1AUTOPTRL1 EP24FIFOFLGS GPIFTRIG RCAP2H

CTH0reserved EP68FIFOFLGS TL2

DTH1AUTOPTRH2 GPIFSGLDATH TH2

E CKCON AUTOPTRL2 GPIFSGLDATLX

F reserved AUTOPTRSET-UP GPIFSGLDATLNOX

Table 3-2. Default ID Values for FX2LP

Default VID/PID/DID

Vendor ID 0x04B4 Cypress Semiconductor

Product ID 0x8613 EZ-USB FX2LP

Device release 0xAnnn Depends on chip revision

(nnn = chip revision where first

silicon = 001)

Note:

2. The I

C bus SCL and SDA pins must be pulled up, even if an EEPROM is not connected. Otherwise this detection method does not work properly.

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