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ATmega8515(L)

Table 84. Fuse Low Byte

Fuse Low Byte

Bit no

Description

Default value

 

 

 

 

 

BODLEVEL

7

Brown-out Detector trigger

1

(unprogrammed)

level

 

 

 

 

 

 

 

 

 

BODEN

6

 

1

(unprogrammed, BOD

Brown-out Detector enable

disabled)

 

 

 

 

 

 

 

SUT1

5

Select start-up time

1

(unprogrammed)(1)

SUT0

4

Select start-up time

0

(programmed)(1)

CKSEL3

3

Select Clock source

0

(programmed)(2)

CKSEL2

2

Select Clock source

0

(programmed)(2)

CKSEL1

1

Select Clock source

0

(programmed)(2)

CKSEL0

0

Select Clock source

1

(unprogrammed)(2)

Notes: 1. The default value of SUT1..0 results in maximum start-up time. See Table 13 on page 38 for details.

2.The default setting of CKSEL3..0 results in internal RC Oscillator @ 1 MHz. See Table 5 on page 34 for details.

The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits.

Latching of Fuses

The fuse values are latched when the device enters Programming mode and changes of

 

the fuse values will have no effect until the part leaves Programming mode. This does

 

not apply to the EESAVE Fuse which will take effect once it is programmed. The fuses

 

are also latched on Power-up in Normal mode.

Signature Bytes

Calibration Byte

Calibration Byte

All Atmel microcontrollers have a 3-byte signature code which identifies the device. This code can be read in both Serial and Parallel mode, also when the device is locked. The three bytes reside in a separate address space.

For the ATmega8515 the signature bytes are:

1.$000: $1E (indicates manufactured by Atmel).

2.$001: $93 (indicates 8KB Flash memory).

3.$002: $06 (indicates ATmega8515 device when $001 is $93).

The ATmega8515 has a one-byte calibration value for the internal RC Oscillator. This byte resides in the high byte of address $000 in the signature address space. During reset, this byte is automatically written into the OSCCAL Register to ensure correct frequency of the calibrated RC Oscillator.

The ATmega8515 stores four different calibration values for the internal RC Oscillator. These bytes resides in the signature row high byte of the addresses 0x000, 0x0001, 0x0002, and 0x0003 for 1, 2, 4, and 8 MHz respectively. During Reset, the 1 MHz value is automatically loaded into the OSCCAL Register. If other frequencies are used, the calibration value has to be loaded manually, see “Oscillator Calibration Register – OSCCAL” on page 38 for details.

179

2512G–AVR–03/05

Parallel Programming

Parameters, Pin

Mapping, and

Commands

Signal Names

This section describes how to parallel program and verify Flash Program memory, EEPROM Data memory, Memory Lock bits, and Fuse bits in the ATmega8515. Pulses are assumed to be at least 250 ns unless otherwise noted.

In this section, some pins of the ATmega8515 are referenced by signal names describing their functionality during parallel programming, see Figure 75 and Table 85. Pins not described in the following table are referenced by pin names.

The XA1/XA0 pins determine the action executed when the XTAL1 pin is given a positive pulse. The bit coding is shown in Table 87.

When pulsing WR or OE, the command loaded determines the action executed. The different Commands are shown in Table 88.

Figure 75. Parallel Programming

+5V

RDY/BSY PD1

VCC

OE PD2

PB7 - PB0 DATA

WR PD3

BS1 PD4

XA0 PD5

XA1 PD6

PAGEL PD7

+12 V RESET

BS2 PA0

XTAL1

GND

Table 85. Pin Name Mapping

Signal Name in Programming Mode

Pin Name

I/O

Function

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0: Device is busy programming,

RDY/BSY

 

PD1

O

1: Device is ready for new

 

 

 

 

 

 

 

 

 

command

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PD2

I

Output Enable (Active low)

 

 

OE

 

 

 

 

 

 

 

 

 

 

 

 

PD3

I

Write Pulse (Active low)

 

WR

 

 

 

 

 

 

 

 

 

 

BS1

PD4

I

Byte Select 1 (“0” selects low

byte, “1” selects high byte)

 

 

 

 

 

 

 

 

 

 

 

 

 

XA0

PD5

I

XTAL Action Bit 0

 

 

 

 

XA1

PD6

I

XTAL Action Bit 1

 

 

 

 

 

 

 

 

 

 

PAGEL

PD7

I

Program memory and EEPROM

data Page Load

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BS2

PA0

I

Byte Select 2 (“0” selects low

byte, “1” selects 2’nd high byte)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DATA

PB7-0

I/O

Bi-directional Data bus (Output

 

 

 

when OE is low)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

180 ATmega8515(L)

2512G–AVR–03/05

 

 

 

 

 

 

 

 

 

ATmega8515(L)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 86. Pin Values used to Enter Programming Mode

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pin

 

 

Symbol

 

Value

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PAGEL

 

Prog_enable[3]

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

XA1

 

 

Prog_enable[2]

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

XA0

 

 

Prog_enable[1]

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BS1

 

 

Prog_enable[0]

 

0

 

 

 

 

 

 

 

 

 

 

 

Table 87. XA1 and XA0 Coding

 

 

 

 

 

 

 

 

 

 

 

 

XA1

 

XA0

 

Action when XTAL1 is Pulsed

 

 

 

 

 

 

 

 

 

 

 

0

 

0

 

Load Flash or EEPROM Address (High or low address byte determined by

 

 

 

BS1)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

1

Load Data (High or Low data byte for Flash determined by BS1)

 

 

 

 

 

 

 

 

 

 

 

1

 

0

 

Load Command

 

 

 

 

 

 

 

 

 

 

 

1

 

1

 

No Action, Idle

 

 

 

 

 

 

 

 

 

 

Table 88. Command Byte Bit Coding

 

 

 

 

 

 

 

 

 

 

 

Command Byte

 

Command Executed

 

 

 

 

 

 

 

 

 

 

 

1000 0000

 

Chip Erase

 

 

 

 

 

 

 

 

 

 

 

0100 0000

 

Write Fuse bits

 

 

 

 

 

 

 

 

 

 

 

0010 0000

 

Write Lock bits

 

 

 

 

 

 

 

 

 

 

 

0001 0000

 

Write Flash

 

 

 

 

 

 

 

 

 

 

 

0001 0001

 

Write EEPROM

 

 

 

 

 

 

 

 

 

 

 

0000 1000

 

Read Signature Bytes and Calibration byte

 

 

 

 

 

 

 

 

 

 

 

0000 0100

 

Read Fuse and Lock bits

 

 

 

 

 

 

 

 

 

 

 

0000 0010

 

Read Flash

 

 

 

 

 

 

 

 

 

 

 

0000 0011

 

Read EEPROM

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 89. No. of Words in a Page and No. of Pages in the Flash

Flash Size

Page Size

PCWORD

No. of Pages

PCPAGE

PCMSB

 

 

 

 

 

 

4K words (8K bytes)

32 words

PC[4:0]

128

PC[11:5]

11

 

 

 

 

 

 

Table 90. No. of Words in a Page and No. of Pages in the EEPROM

EEPROM Size

Page Size

PCWORD

No. of Pages

PCPAGE

EEAMSB

 

 

 

 

 

 

512 bytes

4 bytes

EEA[1:0]

128

EEA[8:2]

8

 

 

 

 

 

 

181

2512G–AVR–03/05

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