29.9.3 Data Polling EEPROM

When a new byte has been written and is being programmed into EEPROM, reading the address location being programmed will give the value 0xFF. At the time the device is ready for a new byte, the programmed value will read correctly. This is used to determine when the next byte can be written. This will not work for the value 0xFF, but the user should have the following in mind: As a chip-erased device contains 0xFF in all locations, programming of addresses that are meant to contain 0xFF, can be skipped. This does not apply if the EEPROM is Reprogrammed without chip-erasing the device. In this case, data polling cannot be used for the value 0xFF, and the user will have to wait at least t_{WD_EEPROM} before programming the next byte. See table below for t_{WD_EEPROM} value.

Table 29-14. Minimum Wait Delay Before Writing the Next Flash or EEPROM Location
Symbol	Minimum Wait Delay
t_{WD_FUSE}	4.5ms
t_{WD_FLASH}	4.5ms
t_{WD_EEPROM}	9.0ms
t_{WD_ERASE}	9.0ms

Figure 29-10. Serial Programming Waveforms

Table 29-15. Serial Programming Instruction Set
	Instruction Format
Instruction	Byte 1	Byte 2	Byte 3	Byte 4	Operation
Programming Enable	`1010 1100`	`0101 0011`	`xxxx xxxx`	`xxxx xxxx`	Enable Serial Programming after RESET goes low.
Chip Erase	`1010 1100`	`100x xxxx`	`xxxx xxxx`	`xxxx xxxx`	Chip Erase EEPROM and Flash.
Read Program Memory	`0010 H000`	`0000 aaaa`	`bbbb bbbb`	`oooo oooo`	Read H (high or low) data o from Program memory at word address a:b.
Load Program Memory Page	`0100 H000`	`0000 xxxx`	`xxxb bbbb`	`iiii iiii`	Write H (high or low) data i to Program memory page at word address b. Data Low byte must be loaded before Data High byte is applied within the same address.
Write Program Memory Page	`0100 1100`	`0000 aaaa`	`bbbx xxxx`	`xxxx xxxx`	Write Program memory Page at address a:b.
Read EEPROM Memory	`1010 0000`	`00xx xxxa`	`bbbb bbbb`	`oooo oooo`	Read data o from EEPROM memory at address a:b.
Write EEPROM Memory	`1100 0000`	`00xx xxxa`	`bbbb bbbb`	`iiii iiii`	Write data i to EEPROM memory at address a:b.
Read Lock Bits	`0101 1000`	`0000 0000`	`xxxx xxxx`	`xxoo oooo`	Read Lock Bits. “0” = programmed, “1” = unprogrammed. See Table Lock Bit Byte for details.
Write Lock Bits	`1010 1100`	`111x xxxx`	`xxxx xxxx`	`11ii iiii`	Write Lock Bits. Set bits = “0” to program Lock Bits. See Table Lock Bit Byte for details.
Read Signature Byte	`0011 0000`	`00xx xxxx`	`xxxx xxbb`	`oooo oooo`	Read Signature Byte o at address b.
Write Fuse Bits	`1010 1100`	`1010 0000`	`xxxx xxxx`	`iiii iiii`	Set bits = “0” to program, “1” to unprogram. See Table Fuse Low Byte for details.
Write Fuse High Bits	`1010 1100`	`1010 1000`	`xxxx xxxx`	`iiii iiii`	Set bits = “0” to program, “1” to unprogram. See Table Fuse High Byte for details.
Read Fuse Bits	`0101 0000`	`0000 0000`	`xxxx xxxx`	`oooo oooo`	Read Fuse Bits. “0” = programmed, “1” = unprogrammed. See Table Fuse Low Byte for details.
Read Fuse High Bits	`0101 1000`	`0000 1000`	`xxxx xxxx`	`oooo oooo`	Read Fuse high bits. “0” = programmed, “1” = unprogrammed. See Table Fuse High Byte for details.
Read Calibration Byte	`0011 1000`	`00xx xxxx`	`0000 00bb`	`oooo oooo`	Read Calibration Byte

Note:

a = address high bits

b = address low bits

H = 0 – Low byte, 1 – High byte

o = data out

i = data in

x = don’t care