Отправлено =AVR= 03 октября 2005 г. 03:27 В ответ на: Не наступал и, вроде бы, в новых ревизиях этого уже нет. Или ты имеешь в виду, что можно зациклиться в ресете, если не очищать флаги в MCUSR? отправлено Dir 03 октября 2005 г. 01:04

1. Part may hang in reset

Some parts may get stuck in a reset state when a reset signal is applied when the internal reset state-machine is in a specific state. The internal reset state-machine is in this state for approximately 10 ns immediately before the part wakes up after a reset, and in a 10 ns window when altering the system clock prescaler. The problem is most often seen during In-
System Programming of the device. There are theoretical possibilities of this happening also in run-mode. The following three cases can trigger the device to get stuck in a reset-state:
- Two succeeding resets are applied where the second reset occurs in the 10ns window before the device is out of the reset-state caused by the first reset.
- A reset is applied in a 10 ns window while the system clock prescaler value is updated by software.
- Leaving SPI-programming mode generates an internal reset signal that can trigger this case.

The two first cases can occur during normal operating mode, while the last case occurs only during programming of the device.

Problem Fix/Workaround

The first case can be avoided during run-mode by ensuring that only one reset source is active. If an external reset push button is used, the reset start-up time should be selected such that the reset line is fully debounced during the start-up time.
The second case can be avoided by not using the system clock prescaler.
The third case occurs during In-System programming only. It is most frequently seen when using the internal RC at maximum frequency. If the device gets stuck in the reset-state, turn power off, then on again to get the device out of this state.

• А, кстати, как определить эту ревизию для ATmega88? Особенно интересно по дате, т.к. чип уже впаян. — Dir   (03.10.2005 15:34 85.202.145.55, пустое)
  • Не знаю, надо будет в суппорте спросить. Возможно, не только по дате, но и чтением, например, недокументированного (4-го) Signature Byte — =AVR=   (03.10.2005 16:48 80.92.96.19, пустое)