Rainbow-electronics ATmega32L Manual de usuario descargar pdf (Pagina 270)

270

ATmega32(L)

2503C–AVR–10/02

Data Polling Flash When a page is being programmed into the Flash, reading an address location within

the page being programmed will give the value $FF. At the time the device is ready for a

new page, the programmed value will read correctly. This is used to determine when the

next page can be written. Note that the entire page is written simultaneously and any

address within the page can be used for polling. Data polling of the Flash will not work

for the value $FF, so when programming this value, the user will have to wait for at least

WD_FLASH

before programming the next page. As a chip erased device contains $FF in

all locations, programming of addresses that are meant to contain $FF, can be skipped.

See Table 115 for t

WD_FLASH

value

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 $FF. At the time the device is

ready for a new byte, the programmed value will read correctly. This is used to deter-

mine when the next byte can be written. This will not work for the value $FF, but the user

should have the following in mind: As a chip erased device contains $FF in all locations,

programming of addresses that are meant to contain $FF, can be skipped. This does

not apply if the EEPROM is re-programmed without chip erasing the device. In this

case, data polling cannot be used for the value $FF, and the user will have to wait at

least t

WD_EEPROM

before programming the next byte. See Table 115 for t

WD_EEPROM

value.

Figure 137. SPI Serial Programming Waveforms

Table 115. Minimum Wait Delay before Writing the Next Flash or EEPROM Location

Symbol Minimum Wait Delay

WD_FLASH

4.5 ms

WD_EEPROM

9.0 ms

WD_ERASE

9.0 ms

MSB

LSB

SERIAL CLOCK INPUT

(SCK)

SERIAL DATA INPUT

(MOSI)

(MISO)

SAMPLE

SERIAL DATA OUTPUT

1 2 ... 265 266 267 268 269 270 271 272 273 274 275 ... 312 313

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