17
ATmega169V/L
2514HS–AVR–05/03
Errata
ATmega169 Rev B • 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
6. 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).
5. LCD Contrast Voltage is not Correct
The LCD contrast voltage between 1.8V and 3.1V is incorrect. When the V
CC
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).
4. External Oscillator is Non-functional
The external oscillator does not run with the setup described in the data sheet.
Problem Fix/Workaround
Use other clock source (this will be fixed in rev. C).
Alternative Problem Fix/Workaround
Adding a pull-down on XTAL1 will start the Oscillator.
3. USART
Writing TXEN to zero during transmission causes the transmission to suddenly stop.
The data sheet description tells that the transmission should complete before stop-
ping the USART when TXEN is written to zero.
Problem Fix/Workaround
Ensure that the transmission is complete before writing TXEN to zero (this will be
fixed in rev. C).
2. ADC Measures with Lower Accuracy than Specified
The ADC does not work as intended. There is a positive offset in the result.
Problem Fix/Workaround
This will be fixed in rev. C.
