Rainbow Electronics ATtiny15L - Manual (Page 61)

61
ATtiny15L
1187E–AVR–06/02
Data Polling When a byte is being programmed into the Flash or EEPROM, reading the address
location being programmed will give the value $FF. 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 $FF so when programming this
value, the user will have to wait for at least t
WD_PROG_FL
before programming the next
Flash byte, or t
WD_PROG_EE
before the next EEPROM byte. As a chip-erased device con-
tains $FF in all locations, programming of addresses that are meant to contain $FF can
be skipped. This does not apply if the EEPROM is reprogrammed without chip-erasing
the device. In that case, data polling cannot be used for the value $FF and the user will
have to wait at least t
WD_PROG_EE
before programming the next byte. See Table 30 for
t
WD_PROG_FL
and t
WD_PROG_EE
values.
Figure 34. Low-voltage Serial Programming Waveforms
MSB
MSB
LSB
LSB
SERIAL CLOCK INPUT
PB2(SCK)
SERIAL DATA INPUT
PB0(MOSI)
SERIAL DATA OUTPUT
PB1(MISO)