ATA8741-PXQW【PDF 189/238 页】MCU W/TRANSMITTER ASK/FSK 24QFN

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189

9140CINDCO02/10

ATA8741

28.8 High-voltage Serial Programming Algorithm

To program and verify the ATtiny24/44/84 in the High-voltage Serial Programming mode, the fol-

lowing sequence is recommended (See instruction formats in Table 28-15 on page 192):

28.8.1

Enter High-voltage Serial Programming Mode

The following algorithm puts the device in High-voltage Serial Programming mode:

1. Apply 4.5 - 5.5V between V

and GND.

2. Set RESET pin to 0 and toggle SCI at least six times.

3. Set the Prog_enable pins listed in Table 28-13 on page 188 to 000 and wait at least 100

ns.

4. Apply V

HVRST

- 5.5V to RESET. Keep the Prog_enable pins unchanged for at least t

HVRST

after the High-voltage has been applied to ensure the Prog_enable signature has been

latched.

5. Shortly after latching the Prog_enable signature, the device will activly output data on the

Prog_enable[2]/SDO pin, and the resulting drive contention may increase the power con-

sumption. To minimize this drive contention, release the Prog_enable[2] pin after t

HVRST

has elapsed.

6. Wait at least 50 祍 before giving any serial instructions on SDI/SII.

28.8.2

Considerations for Efficient Programming

The loaded command 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 or reading multiple memory locations.

" Skip writing the data value 0xFF that is the contents of the entire EEPROM (unless the

EESAVE Fuse is programmed) and Flash after a Chip Erase.

" Address High byte needs only be loaded before programming or reading a new 256 word

window in Flash or 256 byte EEPROM. This consideration also applies to Signature bytes

reading.

28.8.3

Chip Erase

The Chip Erase will erase the Flash and EEPROM

(1)

memories plus Lock bits. The Lock bits are

not reset until the Program memory has been completely erased. The Fuse bits are not

changed. A Chip Erase must be performed before the Flash and/or EEPROM are

re-programmed.

Note:

1. The EEPROM memory is preserved during Chip Erase if the EESAVE Fuse is programmed.

1. Load command Chip Erase (see Table 28-15 on page 192).

2. Wait after Instr. 3 until SDO goes high for the Chip Erase cycle to finish.

3. Load Command No Operation.

Table 28-14. High-voltage Reset Characteristics

Supply Voltage

RESET Pin High-voltage Threshold

Minimum High-voltage Period for

Latching Prog_enable

HVRST

4.5V

11.5V

100 ns

5.5V

11.5V

100 ns

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