Electrical – How to simulate adc with avr simulator 2

It's not really possible to give you a definitive explanation of why your device "works" in simulation but not in hardware based on the information provided. I will offer some suggestions though.

1. Did you know avr-gcc has built in support for sleep?
2. There is a table on page 36 of the datasheet describing Wake-up Sources mapped per Sleep Mode. There is a caveat there for: "(1) for INT0 and INT1, only level interrupt." Follow that trail to page 51 which describes the Low Level interrupt:

Note that if a level triggered interrupt is used for wake-up from Power-down, the required level must be held long enough for the MCU to complete the wake-up to trigger the level interrupt. If the level disappears before the end of the Start-up Time, the MCU will still wake up, but no interrupt will be generated. The start-up time is defined by the SUT and CKSEL Fuses as described in “Clock System” on page 24.

The bit time at 9600 baud is about 100 microseconds. Depending on your clock speed and your clock fuse settings I wonder if you could be blowing this budget? Have you tried with lower baud rate settings (e.g. 300 baud)? Can you tell us how you are clocking the chip? If you're using an external crystal (and you probably should be for UART operation) then the start up time is at best 16000 clock cycles!

Aside: This is obviously not related to your problem, but a useful macro provided by avrlibc is _BV(x) which can be used instead of (1 << x)

The reset disable fuse does just that - disables the reset function of the associated pin. If you set that fuse, there is no way to reset the device except:

• Power Cycle
• Watchdog Timer Expiration

In-Circuit Serial Programming (also known as ICSP), I believe, relies on resetting the device by way of the Reset pin, and so you will not be able to reprogram the device once this fuse is set using ICSP. There is more than one way to reprogram an AVR though. If the device supports High Voltage Serial or Parallel programming (HVSP or HVPP) that's always an option. Or if you can include a bootloader on the chip (which can be done with an ATtiny85 for example, not sure about the ATtiny13), that can work too.

That being said, the datasheet section 24.3.3 has the following excerpts:

Special combinations of fuse bits will lock the device for further programming effectively turning it into an OTP device. The following combinations of settings/fuse bits will cause this effect:

• 128 kHz internal oscillator (CKSEL[1..0] = 11), shortest start-up time (SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled RSTDISBL = 0.
• 9.6 MHz internal oscillator (CKSEL[1..0] = 10), shortest start-up time (SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled RSTDISBL = 0.
• 4.8 MHz internal oscillator (CKSEL[1..0] = 01), shortest start-up time (SUT[1..0] = 00), Debugwire enabled (DWEN = 0) or Reset disabled RSTDISBL = 0.

If you have no intention of supporting in circuit programming, you can safely program once then set the reset disable fuse and use the pin's alternate function. You do not want to leave the reset function enabled in production unless you don't care about your device resetting in arbitrary ways. Basically if the pin is "low" for a given period of time, it will reset, end of story. Per the datasheet Table 18-4, the range of possible threshold values for external reset to trip is 0.2*Vcc to 0.9*Vcc... you maybe just be getting lucky with devices that are closer to 0.2*Vcc.