While I have used a great big bright red 10mm push button, I haven't completely broken away from tradition, the interface still relies on the users ability to count and interpret a sequence of flashing lights. The reason for this is that mirco controllers provide a limited number of inputs and outputs. Each of these inputs/outputs can be extremely powerful so using them up with indicators, displays and multiple push buttons is an unacceptable waste of resources.
The data logger user interface
1 Big Red 10mm Push Button
1 Bright Red LED to signal 'Recording'
1 Bright Green LED to signal 'Sending recorded data over the serial interface'
The system has 5 states -
|State||Meaning||Record Indicator||Serial Indicator|
|Idle||Not currently doing anything||Brief flash every 2 seconds||As Record|
|Record||Recording Data to SD Card||On||Off|
|Serial||Reading SD Data and writing to serial||Off||On|
|Memory Full||No more data can be recorded||On 1 Second/Off 1 Second||As Record|
|Error||Something is wrong||Rapid Alternate with Serial||Rapid Alternate with Record|
To move between states the push button must be held for 1 second or more. To enter record from idle 1 Second, to enter Serial from idle 4 Seconds, to exit either record or idle 1 second.
All I need now is a Micro SD Card and the data logger is up and running.