How to count up or down
The DayCounter will start counting up automatically when you plug it in. You don’t need to do anything.
If you want to count down, you first need to increment the Daycounter to the start value: Press the button down repeatedly to increment the days to the value you want, wait at least two seconds and press it again. The display will flash and the start number will be displayed. It is now counting down.
We do this extra button press at the end so that you can start the counter at a precise time, rather than have it start automatically.
If you hold the button down for two seconds, the DayCounter will reset.
There are a bunch of additional hacks you can use this for.
Trigger an action:
In countdown mode, the alarm pins are raised to 5v at the end of day 0. You can use this feature do to pretty much any action, either directly, or via a relay.
By default, the decimal point on the 7-segment display is lit up, so you can check the alarm is working. For starters, just connect an LED and resistor to the wire (any resistor from about 400 – 800 Ohms will be fine).
Wire to Arduino:
You can also wire this directly from an Arduino, both for power and data. Just leave out the ATTiny85 and use our DayCounter Arduino library to talk to the board.
Chain several displays
The 74HC595 has a very cool feature: when you shove another digit in, it pushes out the least significant digit. With an Arduino, we can exploit this to daisy-chain several displays together.
Alternative ATTiny85 Software Loads
The following are software loads you can use to change the behavior of the embedded ATTiny85 microcontroller that comes with the Day Counter. You will need an ISP Programmer (for example, AVRISP mkII or STK500). All our AVR-based boards have a standard 6-pin ISP header so that they can be reprogrammed in-circuit using these tools together with Atmel’s AVR Studio software (free download from Atmel). Just target the ATTiny85 with the hex files below and your Day Counter will behave accordingly.
– counts up once per day if you do nothing after power on. Press button repeatedly during power on to set an inital value, then press again after a few seconds to go into “count down once-per-day mode.”
Count-up-only Load – same as baseline mode except it will count up from your initial value if you set a value at startup, and press again after a few seconds to start counting.
Meta
Download the schematic: daycounter.sch