Hello,
I use a DS3221 modul to wake and send to sleep an ATTINY85 by Interrupt. How long does that interrupt signal of a DS3221 module last?
Actually I run the Attiny at 8MHz internal and would like do reduce the frequence to 1MHz. There is no time-critical in my sketch. Therefore the code should work fine at 1Mhz, but I consider if the interrupt signal will still send the attiny correct to sleep. If the signal is to short, it may not send the Attiny correct to sleep. Where can I find information about how long an interrupt signal lasts? Can anyone measure that? I dont have suitable measuring instruments.
Greetings from Vienna
The INT/SQW pin is a square wave output.
From the datasheet...
Active-Low Interrupt or 1Hz Square-Wave Output. This open-drain pin requires an external pullup
resistor connected to a supply at 5.5V or less. It can be left open if not used. This multifunction
pin is determined by the state of the INTCN bit in the Control register (0Eh). When INTCN is set to
logic 0, this pin outputs a 1Hz square wave. When INTCN is set to logic 1, a match between the
timekeeping registers and either of the alarm registers activates the INT/SQW pin (if the alarm is
enabled). Because the INTCN bit is set to logic 1 when power is first applied, the pin defaults to
an interrupt output with alarms disabled.
The 32KHZ output is also squarewave.
32.768kHz Output (50% Duty Cycle). This open-drain pin requires an external pullup resistor.
When enabled with the EN32KHZ bit in the Status register (0Fh), this output operates on either
power supply. This pin can be left open circuit if not used.
If you mean the DS3231, the alarm output stays low until the MCU clears the alarm flag in the RTC's status register. So it will stay low as long as you want it to.
