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ATMEGA169V Datasheet(PDF) 19 Page - ATMEL Corporation |
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ATMEGA169V Datasheet(HTML) 19 Page - ATMEL Corporation |
19 / 26 page 19 ATmega169/V 2514PS–AVR–07/06 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. ATmega169 Rev B • 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 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). 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). |
Similar Part No. - ATMEGA169V_06 |
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Similar Description - ATMEGA169V_06 |
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