ATMEGA169 View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

ATMEGA169

8-bit Microcontroller with 16K Bytes In-System Programmable Flash

Atmel Corporation 

ATmega169 Rev B

2514P–AVR–07/06

ATmega169/V

Problem Fix / Workaround

– If ATmega169 is the only device in the scan chain, the problem is not visible.

– Select the Device ID Register of the ATmega169 by issuing the IDCODE

instruction or by entering the Test-Logic-Reset state of the TAP controller to

read out the contents of its Device ID Register and possibly data from

succeeding devices of the scan chain. Issue the BYPASS instruction to the

ATmega169 while reading the Device ID Registers of preceding devices of

the boundary scan chain.

– If the Device IDs of all devices in the boundary scan chain must be captured

simultaneously, the ATmega169 must be the first device in the chain.

• Interrupts may be lost when writing the timer registers in the asynchronous timer

• Internal Oscillator Runs at 4 MHz

• LCD Contrast Voltage is not Correct

• External Oscillator is Non-functional

• USART

• ADC Measures with Lower Accuracy than Specified

• Serial Downloading

• IDCODE masks data from TDI input

8. Interrupts may be lost when writing the timer registers in the asynchronous

timer

If one of the timer registers which is synchronized to the asynchronous timer2 clock

is written in the cycle before a overflow interrupt occurs, the interrupt may be lost.

Problem Fix/Workaround

Always check that the Timer2 Timer/Counter register, TCNT2, does not have the

value 0xFF before writing the Timer2 Control Register, TCCR2, or Output Compare

Register, OCR2.

7. Internal Oscillator Runs at 4 MHz

The Internal Oscillator runs at 4 MHz instead of the specified 8 MHz. Therefore, all

Flash/EEPROM programming times are twice as long as specified. This includes

Chip Erase, Byte programming, Page programming, Fuse programming, Lock bit

programming, EEPROM write from the CPU, and Flash Self-Programming.

For this reason, rev-B samples are shipped with the CKDIV8 Fuse unprogrammed.

Problem Fix/Workaround

If 8 MHz operation is required, apply an external clock (this will be fixed in rev. C).

6. LCD Contrast Voltage is not Correct

The LCD contrast voltage between 1.8V and 3.1V is incorrect. When the VCC is

between 1.8V and 3.1V, the LCD contrast voltage drops approx. 0.5V. The current

consumption in this interval is higher than expected.

Problem Fix/Workaround

Contrast will be wrong, but display will still be readable, can be partly compensated

for using the contrast control register (this will be fixed in rev. C).

5. External Oscillator is Non-functional

The external oscillator does not run with the setup described in the datasheet.

Problem Fix/Workaround

Use other clock source (this will be fixed in rev. C).

351

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