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Atmel ATmega128 User Manual
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156
2467S–AVR–07/09
ATmega128
Figure 70.
Timer/Counte
r Timing Diagra
m, Setting o
f OCF2, with Pre
scaler (f
clk_I/O
/8)
Figure 71
shows the setting of OCF2 and th
e clearing of TCNT2 in CTC mode.
Figure 71.
Timer/Counter Timing Diagram, Clear
Ti
mer on Compare Match Mode, with
Pres-
caler (f
clk_I/O
/8)
OCFn
OCRn
TCNTn
OCRn V
alue
OCRn - 1
OCRn
OCRn + 1
OCRn + 2
clk
I/O
clk
Tn
(clk
I/O
/8)
OCFn
OCRn
TCNTn
(CTC)
TO
P
T
OP - 1
TO
P
BO
TT
OM
BOTT
OM + 1
clk
I/O
clk
Tn
(clk
I/O
/8)
155
157
Table of Contents
Table of Features
1
Pin Configurations
2
Overview
2
Block Diagram
3
Atmega103 and Atmega128 Compatibility
4
Pin Descriptions
5
Resources
8
Data Retention
8
About Code Examples
9
AVR CPU Core
10
Architectural Overview
10
Introduction
10
ALU - Arithmetic Logic Unit
11
Status Register
11
General Purpose Register File
12
AVR CPU General Purpose Working Registers
13
Stack Pointer
14
Instruction Execution Timing
14
Reset and Interrupt Handling
15
Interrupt Response Time
17
AVR Atmega128 Memories
18
In-System Reprogrammable Flash Program Memory
18
SRAM Data Memory
19
Memory Configurations
19
Data Memory Map
20
EEPROM Data Memory
21
Data Memory Access Times
21
EEPROM Read/Write Access
21
EEPROM Data Register – EEDR
22
EEPROM Control Register – EECR
22
I/O Memory
26
External Memory Interface
26
External Memory with Sector Select
27
Address Latch Requirements
28
External SRAM Connected to the AVR
28
Pull-Up and Bus-Keeper
29
Timing
29
XMEM Register Description
31
MCU Control Register
31
External Memory Control Register a –XMCRA
31
System Clock and Clock Options
36
Clock Systems and Their Distribution
36
Clock Sources
37
Default Clock Source
38
Device Clocking Options Select
38
Number of Watchdog Oscillator Cycles
38
Crystal Oscillator
39
Low-Frequency Crystal Oscillator
40
Start-Up Times for the Crystal Oscillator Clock Selection
40
External RC Oscillator
40
External RC Oscillator
41
External RC Configuration
41
External RC Oscillator Operating Modes
41
Start-Up Times for the External RC Oscillator Clock Selection
41
Calibrated Internal RC Oscillator
42
Oscillator Calibration Register – OSCCAL
42
External Clock
43
Timer/Counter Oscillator
44
Power Management and Sleep Modes
45
Idle Mode
46
ADC Noise Reduction Mode
46
Power-Down Mode
46
Power-Save Mode
46
Standby Mode
47
Extended Standby Mode
47
Minimizing Power Consumption
48
Analog to Digital Converter
48
Analog Comparator
48
Brown-Out Detector
48
JTAG Interface and On-Chip Debug System
49
System Control and Reset
50
Reset Sources
50
Resetting the AVR
50
Reset Characteristics
51
Reset Logic
51
External Reset
52
Power-On Reset
52
Brown-Out Detection
53
External Reset During Operation
53
Internal Voltage Reference
54
MCU Control and Status Register
54
Watchdog Reset
54
Voltage Reference Enable Signals and Start-Up Time
55
Watchdog Timer
55
Timed Sequences for Changing the Configuration of the Watchdog Timer
58
Interrupt Vectors in Atmega128
60
Interrupt Vector Change Enable
65
I/O Ports
66
I/O Pin Equivalent Schematic
66
Introduction
66
Configuring the Pin
67
Ports as General Digital I/O
67
Port Pin Configurations
68
Reading the Pin Value
68
Synchronization When Reading an Externally Applied Pin Value
68
Synchronization When Reading a Software Assigned Pin Value
69
Digital Input Enable and Sleep Modes
70
Alternate Port Functions
71
Unconnected Pins
71
Generic Description of Overriding Signals for Alternate Functions
72
Special Function IO Register – SFIOR
73
Alternate Functions of Port D
78
Alternate Functions of Port E
81
Port E Pins Alternate Functions
81
Overriding Signals for Alternate Functions PE7..PE4
82
Alternate Functions of Port F
83
Alternate Functions of Port G
85
Register Description for I/O Ports
87
External Interrupts
90
Interrupt Sense Control
91
Asynchronous External Interrupt Characteristics
91
8-Bit Timer/Counter0 with PWM and Asynchronous Operation
93
Overview
93
Timer/Counter Clock Sources
94
Counter Unit
94
Output Compare Unit
95
Compare Match Output Unit
97
Compare Output Mode and Waveform Generation
97
Modes of Operation
98
Normal Mode
98
Clear Timer on Compare Match (CTC) Mode
98
Fast PWM Mode
99
Fast PWM Mode, Timing Diagram
100
Phase Correct PWM Mode
101
Phase Correct PWM Mode, Timing Diagram
101
Timer/Counter Timing Diagrams
102
Timer/Counter Timing Diagram
103
8-Bit Timer/Counter Register Description
104
Waveform Generation Mode Bit Description
105
Compare Match Output Mode
105
Compare Output Mode, Phase Correct PWM Mode
106
Clock Select Bit Description
106
Asynchronous Operation of the Timer/Counter
107
Asynchronous Status Register – ASSR
107
Timer/Counter Interrupt Mask Register – TIMSK
109
Timer/Counter Interrupt Flag Register
109
Timer/Counter Prescaler
110
16-Bit Timer/Counter (Timer/Counter1 and Timer/Counter3)
112
Overview
112
Accessing 16-Bit Registers
115
Timer/Counter Clock Sources
118
Counter Unit
118
Input Capture Unit
119
Input Capture Pin Source
120
Noise Canceler
120
Using the Input Capture Unit
120
Output Compare Units
121
Force Output Compare
122
Using the Output Compare Unit
122
Compare Match Output Unit
123
Modes of Operation
124
Phase and Frequency Correct PWM Mode
129
Timer/Counter Timing Diagrams
131
16-Bit Timer/Counter Register Description
133
SPI Status Register
169
Data Modes
170
Usart
171
Dual USART
171
USART Block Diagram
172
Asynchronous Clock
185
Using MPCM
188
USART Register Description
189
Usartn I/O Data Register – Udrn
189
Usartn Control and Status Register B
190
Examples of Baud Rate Setting
194
Examples of UBRR Settings for Commonly Used Oscillator Frequencies
195
Two-Wire Serial Interface
198
Two-Wire Serial Interface Bus Definition
198
TWI Terminology
198
Electrical Interconnection
198
Data Transfer and Frame Format
199
Transferring Bits
199
START and STOP Conditions
199
Address Packet Format
200
Data Packet Format
200
Combining Address and Data Packets into a Transmission
201
Multi-Master Bus Systems, Arbitration and Synchronization
201
Overview of the TWI Module
204
Scl and SDA Pins
204
Bit Rate Generator Unit
204
Bus Interface Unit
204
Address Match Unit
205
Control Unit
205
TWI Register Description
206
TWI Bit Rate Register
206
TWI Control Register
206
TWI Status Register
207
Interfacing the Application to the TWI in a Typical Transmission
209
Data Transfer in Master Transmitter Mode
214
Status Codes for Master Transmitter Mode
215
Formats and States in the Master Transmitter Mode
216
Master Receiver Mode
217
Data Transfer in Master Receiver Mode
217
Formats and States in the Master Receiver Mode
218
Status Codes for Master Receiver Mode
219
Status Codes for Slave Receiver Mode
221
Slave Transmitter Mode
222
Formats and States in the Slave Receiver Mode
222
Data Transfer in Slave Transmitter Mode
222
Status Codes for Slave Transmitter Mode
223
Formats and States in the Slave Transmitter Mode
224
Combining Several TWI Modes
225
Multi-Master Systems and Arbitration
225
An Arbitration Example
226
Possible Status Codes Caused by Arbitration
226
Special Function IO Register
227
Analog Comparator Control and Status Register
227
ACIS1/ACIS0 Settings
228
Analog Comparator Multiplexed Input
229
Analog to Digital Converter Block Schematic
231
Prescaling and Conversion Timing
233
ADC Prescaler
233
ADC Timing Diagram, First Conversion
234
ADC Timing Diagram, Single Conversion
234
ADC Timing Diagram, Free Running Conversion
234
ADC Conversion Time
235
ADC Input Channels
236
ADC Voltage
236
ADC Noise
236
Analog Input Circuitry
237
Analog Noise Canceling Techniques
237
ADC Power Connections
238
Offset Compensation Schemes
238
ADC Accuracy Definitions
239
Offset Error
239
Gain Error
239
Integral Non-Linearity (INL)
240
Differential Non-Linearity (DNL)
240
ADC Conversion Result
241
Differential Measurement Range
241
Correlation between Input Voltage and Output Codes
242
Voltage Reference Selections for ADC
242
Input Channel and Gain Selections
243
ADC Prescaler Selections
245
TAP Controller State Diagram
248
TAP Controller
248
Using the On-Chip Debug System
249
On-Chip Debug Related Register in I/O Memory
251
Using the JTAG Programming Capabilities
251
Bibliography
251
Bypass Register
253
Device Identification Register
253
Reset Register
253
Boundary-Scan Specific JTAG Instructions
254
General Port Pin Schematic Diagram
257
Additional Scan Signal for the Two-Wire Interface
258
Observe-Only Cell
258
Boundary-Scan Cells for Oscillators and Clock Options
259
General Boundary-Scan Cell Used for Signals for Comparator and ADC
260
Boundary-Scan Signals for the Analog Comparator
261
Boundary-Scan Signals for the ADC
262
Algorithm for Using the ADC
265
Atmega128 Boundary-Scan Order
266
Boot Loader Lock Bits
275
Memory Sections
275
Boot Lock Bit0 Protection Modes (Application Section)
276
Boot Lock Bit1 Protection Modes (Boot Loader Section)
276
Boot Reset Fuse
276
Addressing the Flash During SPM
279
Setting the Boot Loader Lock Bits
281
EEPROM Write Prevents Writing to SPMCSR
281
Reading the Fuse and Lock Bits from Software
281
Preventing Flash Corruption
282
Programming Time for Flash When Using SPM
282
Simple Assembly Code Example for a Boot Loader
282
Atmega128 Boot Loader Parameters
284
Explanation of Different Variables
285
Memory Programming
286
Program and Data Memory Lock Bits
286
Lock Bit Byte
286
Lock Bit Protection Modes
286
Fuse Bits
287
Extended Fuse Byte
287
Latching of Fuses
288
Fuse High Byte
288
Fuse Low Byte
288
Signature Bytes
289
Calibration Byte
289
Signal Names
290
Parallel Programming
290
Pin Name Mapping
290
Pin Values Used to Enter Programming Mode
291
XA1 and XA0 Coding
291
Command Byte Bit Coding
291
Enter Programming Mode
292
Considerations for Efficient Programming
292
Chip Erase
292
Programming the Flash
293
Addressing the Flash Which Is Organized in Pages
294
Programming the EEPROM
295
Programming the Flash Waveforms
295
Reading the Flash
296
Reading the EEPROM
296
Programming the Fuse Low Bits
296
Programming the EEPROM Waveforms
296
Programming the Fuse High Bits
297
Programming the Extended Fuse Bits
297
Programming the Lock Bits
297
Reading the Fuse and Lock Bits
297
Reading the Signature Bytes
298
Reading the Calibration Byte
298
Parallel Programming Characteristics
298
Parallel Programming Timing, Loading Sequence with Timing Requirements
299
Serial Downloading
300
SPI Serial Programming Pin Mapping
300
SPI Serial Programming Algorithm
301
SPI Serial Programming and Verify
301
Data Polling Flash
302
Data Polling EEPROM
302
Minimum Wait Delay before Writing the Next Flash or EEPROM Location
303
SPI Serial Programming Waveforms
303
SPI Serial Programming Instruction Set
304
Programming Via the JTAG Interface
305
Programming Specific JTAG Instructions
305
State Machine Sequence for Changing the Instruction Word
306
Programming Command Register
309
JTAG Programming Instruction
310
Virtual Flash Page Load Register
313
State Machine Sequence for Changing/Reading the Data Word
313
Virtual Flash Page Read Register
314
Entering Programming Mode
315
Leaving Programming Mode
315
Electrical Characteristics
318
Absolute Maximum Ratings
318
DC Characteristics
318
Speed Grades
320
External Clock Drive Waveforms
320
External Clock Drive
320
External RC Oscillator, Typical Frequencies
321
Two-Wire Serial Interface Characteristics
322
Two-Wire Serial Bus Requirements
322
SPI Timing Characteristics
323
SPI Timing Parameters
323
SPI Interface Timing Requirements (Master Mode)
324
SPI Interface Timing Requirements (Slave Mode)
324
ADC Characteristics
325
ADC Characteristics, Differential Channels
326
External Data Memory Timing
328
Typical Characteristics
333
Active Supply Current
333
Active Supply Current Vs. Frequency
334
Active Supply Current Vs. V
334
Power-Down Supply Current
340
Standby Supply Current
342
Pin Pull-Up
343
I/O Pin Pull-Up Resistor Current Vs. Input Voltage
343
Pin Driver Strength
344
I/O Pin Sink Current Vs. Output Voltage
345
Pin Thresholds and Hysteresis
346
BOD Thresholds and Analog Comparator Offset
347
BOD Threshold Vs. Temperature
348
Bandgap Voltage Vs. Operating Voltage
348
Internal Oscillator Speed
349
Watchdog Oscillator Frequency
349
Calibrated 1 Mhz RC Oscillator Frequency Vs. Temperature
349
Calibrated 2 Mhz RC Oscillator Frequency Vs. Temperature
351
Calibrated 2 Mhz RC Oscillator Frequency Vs. V
351
2 Mhz RC Oscillator Frequency Vs. Osccal Value
352
Calibrated 4 Mhz RC Oscillator Frequency Vs. Temperature
352
Calibrated 4 Mhz RC Oscillator Frequency Vs. V
353
4 Mhz RC Oscillator Frequency Vs. Osccal Value
353
Calibrated 8 Mhz RC Oscillator Frequency Vs. Temperature
354
Calibrated 8 Mhz RC Oscillator Frequency Vs. V
354
8 Mhz RC Oscillator Frequency Vs. Osccal Value
355
Brownout Detector Current Vs. V
355
ADC Current Vs. AV
356
Current Consumption in Reset and Reset
358
Pulse Width
358
Reset Pull-Up Resistor Current Vs. Reset Pin Voltage
359
Register Summary
362
Instruction Set Summary
365
Packaging Information
369
Errata
371
Atmega128 Rev. F to M
371
Stabilizing Time Needed When Changing OSCCAL Register
372
IDCODE Masks Data from TDI Input
372
Table of Contents
379
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Atmel ATmega128 Specifications
General
Brand
Atmel
Model
ATmega128
Category
Microcontrollers
Language
English
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