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M3S-DTMF-Tiny is a software library for generating and detecting DTMF (Dual Tone Multi Frequency) tones, and it just requires small memory.

We have the various lineup of MCUs , including R8C Family, which are suitable for use in applications such as single-function home appliances and compact industrial equipment, where the incorporation of more sophisticated functionality or the newest technology, with a negligible increase in cost, is desired. To support such development activities, Renesas offers software libraries with only the essential features for application, at low cost.

Use of M3S-DTMF-Tiny enables you to introduce DTMF tones generation and detection capabilities to your systems designed with supported MCUs.

Release Information

M3S-DTMF-Tiny for the RX Family
Latest Ver.: V.1.00 Release 00
Released: Jul 21, 2011

Latest Ver.: V.1.01 Release 00
Application Note Ver.: Rev.1.00
Released: Mar 6, 2009

Details of upgrade (See Tool News)

Operating Environment


  • Generates tones by using a tone data table (a sampling frequency of 16 kHz), which lightens the load on the CPU.
  • Outputs tones by using the PWM (Pulse Width Modulation) technique and the D/A conversion system.
  • Speedy detection of DTMF
    Enables to detect DTMF signals having a tone duration and pause duration of 40 ms each.
  • Compactly designed for embedded systems: for instance, memory consumption is as follows:
    • For tone generation: approx. 16 Kbytes of ROM, 0 bytes of RAM, and 6 bytes of stack
    • For tone detection: 2 Kbytes of ROM, 81 bytes of RAM, and 19 bytes of stack
  • Includes sample programs which responds to Renesas IDE:
    • In the sample program are included the sample drivers for PWM output and A/D-converter input.

Application examples

  • Signaling system of push-button telephones
  • Phone-answering machines
  • Call center equipment operations
  • Remote control by using the telephones handset
  • Toys
    and other applications


  • Software for DTMF tone generation (library in binary format)
  • Software for DTMF tone detection (library in binary format)
  • Sample software for DTMF tone generation and detection (High-performance Embedded Workshop format workspace : source file that includes a sample driver for PWM output and A/D-converter input)
  • Library function and sample software user's manual and other documents in a complete set

Modular composition

For DTMF tone generation

For DTMF tone detection

Operating Environment

M3S-DTMF-Tiny for the RX600 Series

arget devices RX Family
Applicable compiler C/C++ Compiler Package for RX Family V.1.00 Release 00 or later
Occupied ROM size For tone generation: approx. 16 Kbytes
For tone detection: approx. 1 Kbytes
Occupied RAM size For tone generation: 0 byte, 4 bytes of stack
For tone detection: 51 bytes, 40 bytes of stack


Target devices R8C, M16C/Tiny, H8/300H Tiny
Applicable compiler R8C, M16C/Tiny M3T-NC30WA V.5.44 Release 00 or later
H8/300H Tiny C/C++ Compiler Package for H8SX, H8S, H8 Family V.6.01 Release03 or later
Occupied ROM size For tone generation: approx. 16 Kbytes (R8C Family)
For tone detection: approx. 2 Kbytes (R8C Family)
Occupied RAM size For tone generation: 0 byte, 6 bytes of stack (R8C Family)
For tone detection: 81 bytes, 19 bytes of stack (R8C Family)

Target devices

RX600 Series
R8C Family
M16C Family M16C/Tiny Series
H8 Family H8/300H Tiny Series

Renesas provides evaluation versions of each MCUs free-of-charge. Please download the appropriate file here.

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