Does the ATtiny have another sleep mode besides IDLE?

I'm trying to save power by turning off my ATtiny after a routine has been completed and using a timer interrupt to wake it up. The problem is that the ATtiny only has Timer 1 so if I use the other modes like POWER DOWN I won't be able to wake it back up. However, I don't feel like I'm getting the full power saving capabilities that come with the other modes. So does anyone on here have any idea if there is a mode that doesn't turn off Timer 1 but saves more power than IDLE?

Use the watchdog timer to wake it from power down.

The ATTiny's have a watchdog timer.

(note - You haven't specified which attiny or how you're programming it. if you're using a "virtual bootloader" to program over serial on an ATTiny chip that doesn't have a BOOTRST fuse, you can't use the WDT like this. This only applies if programming through a bootloader - if you program it with an ISP programmer (USBAsp, ArduinoAsISP - anything that uses the SPI pins, basically), and only if the bootloader rewrites the reset and wdt vectors to make itself run at startup. AFAIK, this is only an issue on my core with the attiny841, attiny167 or attiny1634 w/optiboot - the other ones from my core (including the 841/167/1634 if programmed via ISP) either don't use a bootloader, or have BOOTRST fuse (for the 828), and I haven't seen any other recently updated cores with bootloaders for the other ATTiny's. )

Did you check the datasheet? Page 1 of the datasheet for the ATTiny25 lists Low Power Idle, ADC Noise Reduction, and Power-down Modes. They are defined on page 5. Section 7.1 beginning on page 34 gives all the Details for each.

DrAzzy: Use the watchdog timer to wake it from power down.

The ATTiny's have a watchdog timer.

(note - You haven't specified which attiny or how you're programming it. if you're using a "virtual bootloader" to program over serial on an ATTiny chip that doesn't have a BOOTRST fuse, you can't use the WDT like this. This only applies if programming through a bootloader - if you program it with an ISP programmer (USBAsp, ArduinoAsISP - anything that uses the SPI pins, basically), and only if the bootloader rewrites the reset and wdt vectors to make itself run at startup. AFAIK, this is only an issue on my core with the attiny841, attiny167 or attiny1634 w/optiboot - the other ones from my core (including the 841/167/1634 if programmed via ISP) either don't use a bootloader, or have BOOTRST fuse (for the 828), and I haven't seen any other recently updated cores with bootloaders for the other ATTiny's. )

I'm using the ATtiny85, also is the Watchdog Timer just another way of waking up the microprocessor after I have put it to sleep. Meaning that I can use the more power efficient sleep modes?

The watchdog timer is a separate timer that runs on it's own internal low speed oscillator (separate from the system clock). It can be configured either to run an interrupt when it times out, or reset the microcontroller. Depending on how the prescaler is set, it can time out in anywhere from a few milliseconds to 8 seconds. If enabled, it runs during sleep. There is an instruction to reset the WDT.

Typical use cases are: * Have it generate an interrupt after it times out, to wake the chip from sleep. * Have it reset the microcontroller from within software (ie, configure WDT to reset the chip when it times out, and then enter an infinite loop) * Have it act as a "watchdog", by configuring it to reset the chip when it times out, leaving it running full time, and regularly resetting it, so it never gets to time out during normal operation. If the sketch hangs, the WDT won't be reset, and will time out and reset the board.

There are many examples showing how to use the WDT to wake from sleep.