mbed:cycling_computer
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mbed:cycling_computer [2008/11/22 16:28] |
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| + | ====== Cycling Computer ====== | ||
| + | I intend to make a ludicrous bicycle computer, which will do silly things like: | ||
| + | * Measure speed using the optical sensor from an old mouse | ||
| + | * Measure the berth overtakings cars give with ultrasound | ||
| + | * Measure acceleration using an accelerometer | ||
| + | * Log GPS coordinates | ||
| + | * Run a GUI on a Nintendo Game Boy Advance (although I may do this bespoke as well...) | ||
| + | |||
| + | ===== Data ===== | ||
| + | * [[mbed: | ||
| + | * [[mbed: | ||
| + | |||
| + | ===== To Do ===== | ||
| + | ==== Physical ==== | ||
| + | - Photograph bike for purposes of overlay-sketching and progress measurement | ||
| + | - Find packaging for the eletronics | ||
| + | - Decide how to mount sensors / microprocessor onto bike frame | ||
| + | - Create mount-points and place wires (unless wireless is decided upon) | ||
| + | |||
| + | ==== Electronics ==== | ||
| + | * Wheel RPM | ||
| + | - Decide whether to use a reed-switch & magnet, wire-loop & magnet or LDR & LED/ | ||
| + | * Pedal RPM | ||
| + | - As for wheel RPM | ||
| + | * Airspeed | ||
| + | - Buy pressure sensors and calibrate a (remember what the hell it was called - it's in the Windows Journal files, reboot into Windows, export it all and never look back). | ||
| + | * Acceleration | ||
| + | - Get an accelerometer | ||
| + | * Location | ||
| + | - GPS reciever | ||
| + | |||
| + | ==== Software ==== | ||
| + | - Investigate software timers which fire interrupts. Simon said something about these, and I'd not heard of them. They seem a lot simpler than a PWM loopback. Though not nearly as hacky ;-) | ||
| + | - Reference Clock (see below) needs a pull-up (or pull-down) resistor. Just shorting PWM-out to INT-in won't work. | ||
| + | - Use PWM2 to verify accurate rate detection using new reference clock | ||
| + | - Display rate in rpm and kmph. | ||
| + | |||
| + | ===== Roadmap ===== | ||
| + | |||
| + | - Use optical mouse sensor to read speed (and wobble?) | ||
| + | - Probably simplest to avoid using USB mouse, [[http:// | ||
| + | |||
| + | ===== Physical Bike Properties ===== | ||
| + | |||
| + | Rear wheel circumference at 60psi: 2m 4cm (readings were 2m14, 2m04, 2m06, 2m04.5) | ||
| + | |||
| + | |||
| + | |||
| + | ===== Maths ===== | ||
| + | Assuming that the wheel of my bike as a circumference of 1m, and that I reckon the practical upper limit for my bike is 50mph (~80kmph)((I don't expect to be able to //cycle// at this speed, this is just the upper limit I've chosen to design my system for)) then I can expect my bike wheel to do about 20 rotations per second. In order to sample this effectively, | ||
| + | |||
| + | However, I won't have an analog measurement from the wheel. I will have a pulse once per rotation. I can configure the board to fire an interrupt on this pulse (by catching the rising edge, for instance). I can also connect one of the PWM modules to an interrupt and use it to generate my reference clock. | ||
| + | |||
| + | So I can have a '' | ||
| + | |||
| + | ===== 88 subs per second ===== | ||
| + | A " | ||
mbed/cycling_computer.txt · Last modified: 2008/11/22 16:28 (external edit)
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