User manual
Jazda needs a 3V power supply. Depending on how it was assembled, you might have a battery compartment for specific batteries attached to it. 2x 1.2V AA batteries were proved to work continuously for at least a week with the LCD backlight off while idling. 3V button batteries should work without problems as well. 5V supply (like USB) should be safe to use as long as you don't power on the LCD backlight.
By default, the screen is divided into 3 general areas: builtins (top), module list (middle) and module (bottom). The bottom part of the screen shows the active module data and is the only part of the screen when value can ever change meaning.
By default, jazda should have 3 buttons connected to the port on the other side of the board. They correspond to "left", "select" and "right" actions (jazda is usable with 2 buttons as long as you keep the "select" action).
After powering up, you can use "left" and "right" to switch between modules. Some modules support the "select" action - after pressing the "select" button, they can reset, activate some feature or let you access a submenu.
To make the device useful on a bicycle, you must connect it to the sensors. Only one sensor is always connected to the same place: the wheel rotation sensor should always be connected to the single 2-pin connector near the controller.
Currently, the only other sensor is the crank sensor. It should be connected to the same connector as the buttons. The easiest way to check the exact location is to try them all :)
The most useful feature of the device is speed measurement. Your current speed reading is displayed in the top-right corner of the screen. the unit of speed is km/h, with 0.1km/h resolution. Its preferences name is CURRENT_SPEED.
Cadence is measured in RPM (rotations per minute). It displays the value twice - as a number in the top left corner and as a gauge to its right. By default, the gauge's lowest value is 70 and the highest value is 110. There's also a tiny notch on it, showing the optimal RPM (90).
These values can be changed in source in src/builtins/cadence.c.
Its name in preferences.h is CADENCE. It requires CRANK to be enabled.
These modules all refer to a trip - their measurements are bound together. If you perform the "select" action on any of them, they will all reset. To disable the combined reset, remove COMBINED_RESET from preferences.
None of these values will be modified if you're stopped: i.e. your timer will stop and your average speed will stay constant.
The distance unit is km with 10m resolution and the speed unit is km/h with 0.1km/h resolution (the decimal point may not be clearly visible but it is there). Timer can measure up to 255h 59m 59s.
preferences switches: STOPWATCH, DISTANCE, MAXSPEED, AVGSPEED. AVGSPEED requires LONG_CALCULATIONS.
There are two plot modules. They display your speed plotted against distance or time of your travel.
Both of these plots are scaled so that the top pixel corresponds to 51.2km/h. The newest value always appears on the fart right, but if you stop, an empty space will be inserted to mark the stopping point.
The horizontal width of the speed versus time plot is 168s, while for speed versus distance it's 1km. These values can be changed in module sources.
Preferences names: SPEED_VS_DISTANCE_PLOT, SPEED_VS_TIME_PLOT.
This is a module with a simple purpose: provide a means to enable backlight. It doesn't even display any data. Just choose it and issue "select". Its code is BACKLIGHT.
TODO: place photos
The last module is the most complex one. It allows you to set your wheel circumference.
After you "select" it, a small indicator will appear below the first digit. You can move it using "left" & "right".
To change the value of a digit, "select" it (the indicator will change), then use "left" and "right" to subtract or add 1 (the digit on the left can change if you add 1 to 9 or subtract 1 from 0!). Then "select" the new value.
To confirm and exit, move selection to the field past the rightmost digit and "exit". The indicator disappears and you can browse modules again.
Currently, there is no way to discard the changes and exit, but the settings will disappear when you reconnect the battery.
Most modules and builtins have some values that can be customized. There are usually places in the source file, near the beginning. At the current stage, any customization must be performed within the source code, so a good point to start is hacking guide.