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Is it possible to make Capacitive touch operated tone generator with microcontroller?

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Jun 4, 2015
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Hello… Im a mechanical engineer & product designer from india.....Im trying to make a project....for that I need TO produce continuous tone at 6 different frequencies (between 17000hz to20000hz) or (between 20000hz to 260000hz) from single sounder/buzzer. And these 6 frequencies should be operated with 6 capacitive touch points. When ever I touch one of these buttons specific frequency should produce….Can anybody please clear my doubts….

1) Is using microcontroller is my best choice? (Presently im using 555 timers in Astable mode to produce specific frequency with 6 Toggle switches.

2) Is it possible to produce a continuous tone at specific frequency with line of code using microcontroller? Im working around 20k frequency….Most of the micro controllers working speed is several Megahertz does this produce tone brakes or any other problem?

3) What is the smallest & least power consuming microcontroller I can use?

4) How many pins & bits microcontroller im going to need?

Sorry for too many questions. Thank a lot all of you :)

For minimal component count, you'll use a microcontroller that can mimic a touch controller with it's analog inputs. E.g. microchip has application notes about this operation. A separate touch controller like NXP PCF8885 may nevertheless achieve lower power consumption.

You'll preferably use a hardware timer to generate clean output frequencies. All recent microncontrollers have this feature.

When using a microcontroller, well considered utilization of power saving modes is the key. That's probably a topic beyond microncontroller beginner's level.
Thanks a lot for your help.... basically im a product designer(**broken link removed**) i hardly know about electronics...... Can you imagine how much time it will take to make this for a beginner?? Can i find any related tutorials? or any related projects on web? or it is it better to go for a freelancer? How much should i offer for a freelancer?(I really don't know how hard is this thing to make) i wnat to make this within a month....Please suggest me anything help full....

Microchip has some application notes and reference designs dealing with capacitive touch keys, both using dedicated touch controllers and analog function of PIC microcontrollers. Some experience with microcontrollers and knowledge of analog electronics would be necessary to start a design. In so far it's a good idea to seek help in your area. A high school student with microcontroller skills could do it.

ATMEL has some qtouch features for their AVR microcontrollers. Searc the internet on this. and especially on

There are picopower AVRs sepcialized for low power consumption.
Other manufactureres have low power microcontrollers also. One very popular low power microcontroller is the MSP430 if TI.

What max. current do you expect? (Please don´t say "the less the better").
With microcontrollers usually they need some milliamperes when busy, but as soon as they don´t need to wor they could be sent to sleep with very low power consumption.
You can use sleep mode very flexible. Even some milliseconds in "sleep" are possible or 99.99% of a day (or hour or week...) is possible.
(I bet the microcontroller uses less power than 6 NE555, most probably less than one NE555. But it depends on what you want the microcontroller to do.)

Tone generation - square wave - can be done with integrated hardware. Look for "waveform generationn" or "PWM generation".

How exact do you need the frequencies to be?

Hope that helps

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