Difference between revisions of "Digital FD-8 pedal"
From Just in Time
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* auto-calibration, i.e. no need for pots to set the right trigger points. | * auto-calibration, i.e. no need for pots to set the right trigger points. | ||
| + | == Bill of material == | ||
We're currently working on a "more digital" version, based on a MCU and a digital potentiometer. We're using the following hardware: | We're currently working on a "more digital" version, based on a MCU and a digital potentiometer. We're using the following hardware: | ||
| − | * attiny13 MCU | + | |
| − | * Two MCP41010 digital potentiometers in series (10K each, because when we sourced it, a single 50K version was a lot more expensive on ebay). | + | * attiny13 MCU ([{{EbaySearch|attiny13+10pcs}} ebay]) with effectively 5 io pins and 10-bit ADC. |
| − | * Honeywell SS490 ratiometric hall effect sensor. | + | * Two MCP41010 digital potentiometers ([{{EbaySearch|mcp41010+pcs}} ebay]) in series (10K each, because when we sourced it, a single 50K version was a lot more expensive on ebay). |
| + | * Honeywell SS490 ratiometric hall effect sensor as in the non-MCU version, or alternatively an Allegro A1302 (Just ordered a set [{{EbaySearch|ratiometric+a1302}} on ebay]. Should be comparable to the Honeywell if used in a 5V setup) | ||
Additionally (and optionally) we're adding: | Additionally (and optionally) we're adding: | ||
| − | |||
| − | |||
| − | The circuit essentialy does the following: | + | * a momentary switch (button) to explicitly start calibration (we're still researching complete autocalibration). |
| + | * an LED,every MCU project should have an LED | ||
| + | |||
| + | If we forego the LED and switch we could use the pin to separately control the second potmeter, providing an extra bit of precision. | ||
| + | |||
| + | ==Mode of operation== | ||
| + | The circuit essentialy does the following: Measure the output voltage of the hall sensor using the ADC. Determine a corresponding resistance and program that resistance value in the digital pots. Easy. | ||
Revision as of 13:57, 7 February 2014
In Roland FD-8 Issues: Hall Sensor Modification we described how a ratiometric hall sensor could replace the resistor film to solve reliability issues with the Roland FD-8 high hat pedals. Even though that Hall Sensor hack works, an MCU based approach might have some additional advantages:
- complete variable resistance to be compatible with other drum modules
- adjustable sensitivity curve
- detection of foot-down velocity (which is currently limited to one static velocity)
- auto-calibration, i.e. no need for pots to set the right trigger points.
Bill of material
We're currently working on a "more digital" version, based on a MCU and a digital potentiometer. We're using the following hardware:
- attiny13 MCU (ebay) with effectively 5 io pins and 10-bit ADC.
- Two MCP41010 digital potentiometers (ebay) in series (10K each, because when we sourced it, a single 50K version was a lot more expensive on ebay).
- Honeywell SS490 ratiometric hall effect sensor as in the non-MCU version, or alternatively an Allegro A1302 (Just ordered a set on ebay. Should be comparable to the Honeywell if used in a 5V setup)
Additionally (and optionally) we're adding:
- a momentary switch (button) to explicitly start calibration (we're still researching complete autocalibration).
- an LED,every MCU project should have an LED
If we forego the LED and switch we could use the pin to separately control the second potmeter, providing an extra bit of precision.
Mode of operation
The circuit essentialy does the following: Measure the output voltage of the hall sensor using the ADC. Determine a corresponding resistance and program that resistance value in the digital pots. Easy.