Detect DTMF tones accurately and effortlessly with MT8870D and MK64FN1M0VDC12
Revolutionizing tone decoding: Unveiling the ultimate DTMF receiver
Published Oct 22, 2023
Click board™
DTMF Decoder Click
Dev Board
Clicker 2 for Kinetis
Compiler
NECTO Studio
MCU
MK64FN1M0VDC12
Explore the cutting-edge DTMF receiver that seamlessly combines band-split filtering and digital decoding, enabling the detection and decoding of all 16 DTMF tone-pairs into a 4-bit code
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Hardware Overview
How does it work?
DTMF Decoder Click is based on the MT8870D, an integrated DTMF receiver with enhanced sensitivity from Microchip Technology. It offers low power consumption and high performance. It consists of a band split filter section separating the high and low group tones, followed by a digital counting section that verifies the received tones' frequency and duration before passing the corresponding code to the output bus. This Click board™ has two ways to detect tones: a mobile phone with a 3.5mm jack, which provides the DTMF signals to the MT8870D decoder, or an onboard microphone to listen to the DTMF tones generated by the cell phone. The MT8870D uses digital counting techniques to detect and decode all 16 DTMF tone-pairs into a 4-bit code. DTMF
Decoder Click communicates with MCU using a standard I2C 2-Wire interface, with a clock frequency up to 100kHz in the Standard and 400kHz in the Fast Mode. Using the PCA9536 port expander that communicates with the MCU via I2C communication, it is possible to display visually, in binary form, the digit of the pressed number. The digit in binary form is then visually displayed using four red LEDs, labeled from Q1 to Q4, in the board's upper right corner. This Click board™ also has a power-down feature routed on the CS pin of the mikroBUS™ socket labeled as PWD. A logic high applied to pin PWD will power down the device to minimize the power consumption in a Standby mode, which stops the oscillator and the filters' functions. Also, it uses the
interrupt pin of the mikroBUS™ labeled as STD with an additional LED indicator signaling that a received tone pair has been registered, and the INH pin, which inhibits the detection of tones representing characters A, B, C, and D. The output code will remain the same as the previously detected code. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.
Features overview
Development board
Clicker 2 for Kinetis is a compact starter development board that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It comes with an onboard 32-bit ARM Cortex-M4F microcontroller, the MK64FN1M0VDC12 from NXP Semiconductors, two mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a JTAG programmer connector, and two 26-pin headers for interfacing with external electronics. Its compact design with clear and easily recognizable silkscreen markings allows you to build gadgets with unique functionalities and
features quickly. Each part of the Clicker 2 for Kinetis development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the Clicker 2 for Kinetis programming method, using a USB HID mikroBootloader or an external mikroProg connector for Kinetis programmer, the Clicker 2 board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Micro-B cable, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or
using a Li-Polymer battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, reset button, and several user-configurable buttons and LED indicators. Clicker 2 for Kinetis is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
1024
Silicon Vendor
NXP
Pin count
121
RAM (Bytes)
262144
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Clicker 2 for Kinetis as your development board.
Track your results in real time
Application Output via Debug Mode
1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.
2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.
Software Support
Library Description
This library contains API for DTMF Decoder Click driver.
Key functions:
dtmfdecoder_tone_read- This function reads a last registered tone and returns decoded data in character formatdtmfdecoder_delayed_steering_check- This function checks the state of the StD pindtmfdecoder_powerdown_off- This function powers up the device and along with the oscillator
Open Source
Code example
This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.
/*!
* @file main.c
* @brief DTMFDecoder Click example
*
* # Description
* This example shows the basic tone capture of
* DTMF frequencies, decoding and representing
* them on the UART LOG.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes I2C and UART LOG drivers and powers
* on the device.
*
* ## Application Task
* Checks the delayed steering for incoming tones
* and decoding them on the UART LOG. Holding the
* same key will recognize multiple tone generation,
* the tone register delay constant can be set to
* adjust the tolerance.
*
* @author Stefan Nikolic
*
*/
#include "board.h"
#include "log.h"
#include "dtmfdecoder.h"
static dtmfdecoder_t dtmfdecoder;
static log_t logger;
static const uint16_t tone_register_delay = 200;
void application_init ( void ) {
log_cfg_t log_cfg; /**< Logger config object. */
dtmfdecoder_cfg_t dtmfdecoder_cfg; /**< Click config object. */
/**
* Logger initialization.
* Default baud rate: 115200
* Default log level: LOG_LEVEL_DEBUG
* @note If USB_UART_RX and USB_UART_TX
* are defined as HAL_PIN_NC, you will
* need to define them manually for log to work.
* See @b LOG_MAP_USB_UART macro definition for detailed explanation.
*/
LOG_MAP_USB_UART( log_cfg );
log_init( &logger, &log_cfg );
log_info( &logger, " Application Init " );
// Click initialization.
dtmfdecoder_cfg_setup( &dtmfdecoder_cfg );
DTMFDECODER_MAP_MIKROBUS( dtmfdecoder_cfg, MIKROBUS_1 );
err_t init_flag = dtmfdecoder_init( &dtmfdecoder, &dtmfdecoder_cfg );
if ( init_flag == I2C_MASTER_ERROR ) {
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
dtmfdecoder_default_cfg ( &dtmfdecoder );
Delay_ms( 100 );
log_info( &logger, " Application Task " );
}
void application_task ( void ) {
uint8_t result;
if ( dtmfdecoder_delayed_steering_check( &dtmfdecoder ) ) {
result = dtmfdecoder_tone_read( &dtmfdecoder );
log_printf( &logger, " Detected key tone:\t%c\r\n", result );
Delay_ms( tone_register_delay );
}
}
void main ( void ) {
application_init( );
for ( ; ; ) {
application_task( );
}
}
// ------------------------------------------------------------------------ END
