Cypress Semiconductor FX2LP Technical Information Seite 291

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Chapter 13. Input/Output Page 13-17
11. Set STOP=1.
12. Read the last byte from I2DAT immediately (the next instruction) after setting the STOP bit.
This retrieves the last data byte without initiating an extra read transaction (nine more SCL
pulses) on the I²C-compatible bus.
* If INT3 is enabled, each Wait for DONE=1 step can be interrupt-driven and handled by an interrupt service
routine. See Chapter 4, "Interrupts" for more details.
13.5 EEPROM Boot Loader
Whenever the FX2 is taken out of reset via the reset pin, its boot loader checks for the presence of
an EEPROM on the I²C-compatible bus. If an EEPROM is detected, the loader reads the first
EEPROM byte to determine how to enumerate (specifically, whether to supply hard-wired ID infor-
mation or read the ID from the EEPROM). The various enumeration modes are described in Chap-
ter 3, "Enumeration and ReNumeration".
The FX2 boot loader supports two I²C-compatible EEPROM types:
EEPROMs with slave address 1010 that use an 8-bit internal address (e.g., 24LC00,
24LC01/B, 24LC02/B).
EEPROMs with slave address 1010 that use a 16-bit internal address (e.g., 24AA64,
24LC128, 24AA256).
EEPROMs with densities up to 256 bytes require only a single address byte; larger EEPROMs
require two address bytes. The FX2 must determine which EEPROM type is connected one or
two address bytes so that it can properly read the EEPROM.
The FX2 uses the EEPROM device-address pins A2, A1, and A0 to determine whether to send
out one or two bytes of address. As shown in Table 13-11, single-byte-address EEPROMs must be
strapped to address 000, while double-byte-address EEPROMs must be strapped to address 001.
* This EEPROM does not have device-address pins
Table 13-11. Strap Boot EEPROM Address Lines to These Values
Bytes
Example
EEPROM
A2 A1 A0
16 24LC00* N/A N/A N/A
128 24LC01 0 0 0
256 24LC02 0 0 0
4K 24LC32 0 0 1
8K 24LC64 0 0 1
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