Atmel ATmega48PV

Atmel ATmega48PV

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441

8025I–AVR–02/09

ATmega48P/88P/168P/328P

Problem Fix/ Workaround

None

32.4.3 Rev A

•

Unstable 32 kHz Oscillator

1. Unstable 32 kHz Oscillator

The 32 kHz oscillator does not work as system clock.

The 32 kHz oscillator used as asynchronous timer is inaccurate.

Problem Fix/ Workaround

None

Table of Contents

Default Chapter1
- Features1
1 Pin Configurations2
- Pin Descriptions3
2 Overview4
- Block Diagram5
- Comparison between Atmega48P, Atmega88P, Atmega168P, and Atmega328P6
3 About7
- Disclaimer7
- Resources7
- Data Retention7
- Code Examples7
4 AVR CPU Core8
- Overview8
- ALU - Arithmetic Logic Unit9
- Status Register9
- General Purpose Register File11
- Stack Pointer12
- Instruction Execution Timing13
- Reset and Interrupt Handling14
5 AVR Memories16
- Overview16
- In-System Reprogrammable Flash Program Memory16
- SRAM Data Memory18
- EEPROM Data Memory19
- I/O Memory20
- Register Description21
6 System Clock and Clock Options26
- Clock Systems and Their Distribution26
- Clock Sources27
- Low Power Crystal Oscillator28
- Full Swing Crystal Oscillator30
- Low Frequency Crystal Oscillator32
- Calibrated Internal RC Oscillator33
- Khz Internal Oscillator33
- External Clock34
- Clock Output Buffer35
- Timer/Counter Oscillator35
- System Clock Prescaler35
- Register Description37
7 Power Management and Sleep Modes39
- Sleep Modes39
- BOD Disable40
- Idle Mode40
- ADC Noise Reduction Mode40
- Power-Down Mode41
- Power-Save Mode41
- Standby Mode41
- Extended Standby Mode41
- Power Reduction Register42
- Minimizing Power Consumption42
- Register Description44
8 System Control and Reset46
- Resetting the AVR46
- Reset Sources46
- Power-On Reset47
- External Reset48
- Brown-Out Detection48
- Watchdog System Reset49
- Internal Voltage Reference49
- Watchdog Timer50
- Register Description54
9 Interrupts57
- Interrupt Vectors in Atmega48P57
- Interrupt Vectors in Atmega88P59
- Interrupt Vectors in Atmega168P62
- Interrupt Vectors in Atmega328P65
- Register Description68
10 External Interrupts70
- Pin Change Interrupt Timing70
- Register Description71
11 O-Ports75
- Overview75
- Ports as General Digital I/O76
- Alternate Port Functions80
- Register Description92
12 8-Bit Timer/Counter0 with PWM94
- Features94
- Overview94
- Timer/Counter Clock Sources96
- Counter Unit96
- Output Compare Unit97
- Compare Match Output Unit98
- Modes of Operation99
- Timer/Counter Timing Diagrams104
- Register Description106
16 Bit Timer/Counter1 with PWM113
- Features113
- Overview113
- Accessing 16-Bit Registers115
- Timer/Counter Clock Sources118
- Counter Unit119
- Input Capture Unit120
- Output Compare Units122
- Compare Match Output Unit124
- Modes of Operation125
- Timer/Counter Timing Diagrams132
- Register Description134
14 Timer/Counter0 and Timer/Counter1 Prescalers141
- Internal Clock Source141
- Prescaler Reset141
- External Clock Source141
- Register Description143
15 8-Bit Timer/Counter2 with PWM and Asynchronous Operation144
- Features144
- Overview144
- Timer/Counter Clock Sources145
- Counter Unit145
- Output Compare Unit146
- Compare Match Output Unit148
- Modes of Operation149
- Timer/Counter Timing Diagrams153
- Asynchronous Operation of Timer/Counter2155
- Timer/Counter Prescaler156
- Register Description158
16 SPI - Serial Peripheral Interface166
- Features166
- Overview166
- SS Pin Functionality171
- Data Modes171
- Register Description173
17 Usart0176
- Features176
- Overview176
- Clock Generation177
- Frame Formats180
- USART Initialization182
- Data Transmission - the USART Transmitter183
- Data Reception - the USART Receiver186
- Asynchronous Data Reception190
- Multi-Processor Communication Mode193
- Register Description195
- Examples of Baud Rate Setting199
18 USART in SPI Mode204
- Features204
- Overview204
- Clock Generation204
- SPI Data Modes and Timing205
- Frame Formats206
- Data Transfer208
- AVR USART MSPIM Vs. AVR SPI210
- Register Description211
19 2-Wire Serial Interface214
- Features214
- Wire Serial Interface Bus Definition214
- Data Transfer and Frame Format216
- Multi-Master Bus Systems, Arbitration and Synchronization218
- Overview of the TWI Module221
- Using the TWI223
- Transmission Modes227
- Multi-Master Systems and Arbitration240
- Register Description241
20 Analog Comparator246
- Overview246
- Analog Comparator Multiplexed Input246
- Register Description247
21 Analog-To-Digital Converter250
- Features250
- Overview250
- Starting a Conversion252
- Prescaling and Conversion Timing253
- Changing Channel or Reference Selection255
- ADC Noise Canceler256
- ADC Conversion Result261
- Temperature Measurement261
- Register Description262
22 Debugwire On-Chip Debug System267
- Features267
- Overview267
- Physical Interface267
- Software Break Points268
- Limitations of Debugwire268
- Register Description268
23 Self-Programming the Flash, Atmega48P269
- Overview269
- Addressing the Flash During Self-Programming270
- Register Description275
24 Boot Loader Support - Read-While-Write Self-Programming, Atmega88P, Atmega168P and Atmega328P277
- Features277
- Overview277
- Application and Boot Loader Flash Sections277
- Read-While-Write and no Read-While-Write Flash Sections278
- Boot Loader Lock Bits280
- Entering the Boot Loader Program281
- Addressing the Flash During Self-Programming282
- Self-Programming the Flash282
- Register Description292
25 Memory Programming294
- Program and Data Memory Lock Bits294
- Fuse Bits295
- Signature Bytes298
- Calibration Byte299
- Page Size299
- Parallel Programming Parameters, Pin Mapping, and Commands299
- Parallel Programming301
- Serial Downloading308
26 Electrical Characteristics313
- Absolute Maximum Ratings313
- DC Characteristics313
- Speed Grades316
- Clock Characteristics319
- System and Reset Characteristics320
- SPI Timing Characteristics321
- Wire Serial Interface Characteristics323
- ADC Characteristics - Preliminary Data325
- Parallel Programming Characteristics326
27 Typical Characteristics328
- Atmega48P Typical Characteristics329
- Atmega88P Typical Characteristics353
- Atmega168P Typical Characteristics377
- Atmega328P Typical Characteristics401
28 Register Summary425
29 Instruction Set Summary429
30 Ordering Information432
- Atmega48P432
- Atmega88P433
- Atmega168P434
- Atmega328P435
31 Packaging Information436
- M1-A438
32 Errata440
- Errata Atmega48P440
- Errata Atmega88P440
- Errata Atmega168P440
- Errata Atmega328P440
33 Datasheet Revision History442
- Rev. 2545I-02/09442
- Rev. 2545H-02/09442
- Rev. 2545G-01/09442
- Rev. 2545F-08/08443
- Rev. 2545E-08/08443
- Rev. 2545D-03/08443
- Rev. 2545C-01/08443
- Rev. 2545B-01/08444
- Rev. 2545A-07/07444

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