atmega169v ATMEL Corporation, atmega169v Datasheet - Page 20

• Manufacturer Part Number: atmega169v
• Description: Atmega169 8-bit With 16k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

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ATmega169/V
4. USART
3. ADC Measures with Lower Accuracy than Specified
2. Serial downloading
1. IDCODE masks data from TDI input
Alternative Problem Fix/Workaround
Adding a pull-down on XTAL1 will start the Oscillator.
Writing TXEN to zero during transmission causes the transmission to suddenly stop.
The datasheet 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).
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.
When entering Serial Programming mode the second byte will not echo back as
described in the Serial Programming algorithm.
Problem Fix/Workaround
Check if the third byte echoes back to ensure that the device is in Programming
mode (this will be fixed in rev. C).
The JTAG instruction IDCODE is not working correctly. Data to succeeding devices
are replaced by all-ones during Update-DR.
Problem Fix / Workaround
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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.
2514PS–AVR–07/06