AN2131-DK001 Cypress Semiconductor Corp, AN2131-DK001 Datasheet - Page 73

• Manufacturer Part Number: AN2131-DK001
• Description: KIT EZ-USB DEVELOPMENT BOARD
• Manufacturer: Cypress Semiconductor Corp

Specifications of AN2131-DK001

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 428-1333

When the EZ-USB chip comes out of reset, the EZ-USB boot loader checks for the pres-
ence of an EEPROM on its I
EEPROM byte to determine how to enumerate (specifically, whether to supply ID infor-
mation from the EZ-USB core or from the EEPROM). The various enumeration modes
are described in Chapter 5, "EZ-USB Enumeration and ReNumeration ."
Prior to reading the first EEPROM byte, the boot loader must set an address counter inside
the EEPROM to zero. It does this by sending a control byte (write) to select the
EEPROM, followed by a zero address to set the internal EEPROM address pointer to zero.
Then it issues a control byte (read), and reads the first EEPROM byte.
The EZ-USB boot loader supports two I
EEPROMs with densities up to 256 bytes require loading a single address byte. Larger
EEPROMs require loading two address bytes.
The EZ-USB I
or two address bytes—so that it can properly reset the EEPROM address pointer to zero
before reading the EEPROM. For the single-byte address part, it must send a single zero
byte of address, and for the two-byte address part it must send two zero bytes of address.
Because there is no direct way to detect which EEPROM type—single or double
address—is connected, the I
to determine whether to send out one or two bytes of address. This algorithm requires that
the EEPROM address lines are strapped as shown in Table 4-2. Single-byte-address
EEPROMs are strapped to address 000 and double-byte-address EEPROMs are strapped
to address 001.
Page 4-12
4.10
•
•
EEPROMs with address A[7..4]=1010 that use an 8-bit address (example:
24LC00, LC01/A, LC02/A).
EEPROMs with address A[7..4]=1010 that use a 16-bit address (example:
24LC00, LC01/A, LC02/A).
I
2
C Boot Loader
2
C controller needs to determine which EEPROM type is connected—one
2
2
C controller uses the EEPROM address pins A2, A1, and A0
C bus. If an EEPROM is detected, the loader reads the first
Chapter 4. EZ-USB CPU
2
C EEPROM types:
EZ-USB TRM v1.9