Stabilizing Time Needed When Changing Osccal Register; Idcode Masks Data From Tdi Input - Atmel ATmega128 Manual

ATmega128
372
SEI

4. Stabilizing time needed when changing OSCCAL Register

After increasing the source clock frequency more than 2% with settings in the OSCCAL reg-
ister, the device may execute some of the subsequent instructions incorrectly.
Problem Fix / Workaround
The behavior follows errata number 3., and the same Fix / Workaround is applicable on this
errata.

5. IDCODE masks data from TDI input

The JTAG instruction IDCODE is not working correctly. Data to succeeding devices are
replaced by all-ones during Update-DR.
Problem Fix / Workaround
– If ATmega128 is the only device in the scan chain, the problem is not visible.
– Select the Device ID Register of the ATmega128 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 ATmega128 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 ATmega128 must be the fist device in the chain.
6. Reading EEPROM by using ST or STS to set EERE bit triggers unexpected interrupt
request.
Reading EEPROM by using the ST or STS command to set the EERE bit in the EECR reg-
ister triggers an unexpected EEPROM interrupt request.
Problem Fix / Workaround
Always use OUT or SBI to set EERE in EECR.
; set global interrupt enable
2467S–AVR–07/09