Rainbow-electronics ATmega8515L Uživatelský manuál stáhnout pdf (Strana 180)

180

ATmega8515(L)

2512A–AVR–04/02

Parallel Programming

Enter Programming Mode The following algorithm puts the deviceinParallel Programming mode:

1. Apply 4.5 - 5.5 V between V

andGND.

2. Set RESET

to “0” and toggle XTA L1atleast six times.

3. Set theProg_enable pinslisted in Table86 on page 179 to “0000” andwait at

least 100 ns.

4. Apply 11.5 - 12.5V to RESET

.Any activity on Prog_enable pinswithin 100 ns

after+12V hasbeen applied to RESET

,will causethe devicetofail entering Pro-

gramming mode.

Note, ifExternalCrystal orExternal RCconfiguration isselected, it may not be possible

to apply qualifiedXTAL1 pulses. In such cases, the following algorithm should be

followed:

1. Set Prog_enable pinslisted in Table86 on page 179 to “0000”.

2. Apply 4.5 - 5.5V between V

andGNDsimultanously as 11.5 - 12.5V is applied

to RESET

3. Wait 100 ns.

4. Re-program the fuses to ensurethat ExternalClock isselected asclock source

(CKSEL3:0 = 0b0000)IfLock bits are programmed, a ChipErase command

must beexecutedbefore changing the fuses.

5. Exit Programming mode by power the device downorbybringing RESET

pin to

0b0.

6. Entering Programming mode with theoriginal algorithm, asdescribed above.

Considerations for Efficient

Programming

The loadedcommand and address are retained in the device during programming. For

efficient programming, the following should be considered.

•The command needs only be loaded once when writing orreading multiplememory

locations.

• Skipwriting the data value $FF, that is the contents of the entire EEPROM (unless

the EESAVEFuseisprogrammed) andFlash after a ChipErase.

•Address highbyte needs only be loadedbefore programming orreadinganew 256

word window in Flash or 256byte EEPROM.Thisconsideration alsoapplies to

Signature bytesreading.

Chip Erase The ChipErase will erasethe Flash andEEPROM

(1)

memoriesplusLock bits.The Lock

bits are not reset until the program memory hasbeen completely erased.The Fuse bits

are not changed.AChipErasemust be performedbeforethe Flash isreprogrammed.

Note: 1. The EEPRPOM memory ispreservedduring ChipEraseif the EESAVEFuseis

programmed.

LoadCommand “ChipErase”

1. Set XA1,XA0 to “10”. This enablescommandloading.

2. Set BS1to“0”.

3. Set DATA to “1000 0000”. This is the commandforChipErase.

4. Give XTA L1apositive pulse. Thisloads the command.

5. Give WR

a negative pulse. Thisstarts the ChipErase. RDY/BSY goeslow.

6. Wait until RDY/BSY

goeshighbefore loadinganewcommand.

1 2 ... 175 176 177 178 179 180 181 182 183 184 185 ... 222 223

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