Detect DTMF tones accurately and effortlessly with MT8870D and ATmega324PA
Revolutionizing tone decoding: Unveiling the ultimate DTMF receiver
Published Jul 11, 2024
Click board™
DTMF Decoder Click
Dev. board
EasyAVR v8
Compiler
NECTO Studio
MCU
ATmega324PA
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
EasyAVR v8 is a development board designed to rapidly develop embedded applications based on 8-bit AVR microcontrollers (MCUs). Redesigned from the ground up, EasyAVR v8 offers a familiar set of standard features, as well as some new and unique features standard for the 8th generation of development boards: programming and debugging over the WiFi network, connectivity provided by USB-C connectors, support for a wide range of different MCUs, and more. The development board is designed so that the developer has everything that might be needed for the application development, following the Swiss Army knife concept: a highly advanced programmer/debugger module, a reliable power supply module, and a USB-UART connectivity option. EasyAVR v8 board offers several different DIP sockets, covering a wide range of 8-bit AVR MCUs, from the smallest
AVR MCU devices with only eight pins, all the way up to 40-pin "giants". The development board supports the well-established mikroBUS™ connectivity standard, offering five mikroBUS™ sockets, allowing access to a huge base of Click boards™. EasyAVR v8 offers two display options, allowing even the basic 8-bit AVR MCU devices to utilize them and display graphical or textual content. One of them is the 1x20 graphical display connector, compatible with the familiar Graphical Liquid Crystal Display (GLCD) based on the KS108 (or compatible) display driver, and EasyTFT board that contains TFT Color Display MI0283QT-9A, which is driven by ILI9341 display controller, capable of showing advanced graphical content. The other option is the 2x16 character LCD module, a four-bit display module with an embedded character-based display controller. It
requires minimal processing power from the host MCU for its operation. There is a wide range of useful interactive options at the disposal: high-quality buttons with selectable press levels, LEDs, pull-up/pulldown DIP switches, and more. All these features are packed on a single development board, which uses innovative manufacturing technologies, delivering a fluid and immersive working experience. The EasyAVR v8 development board is also integral to the MIKROE rapid development ecosystem. Natively supported by the MIKROE Software toolchain, backed up by hundreds of different Click board™ designs with their number growing daily, it covers many different prototyping and development aspects, thus saving precious development time.
Microcontroller Overview
MCU Card / MCU
Architecture
AVR
MCU Memory (KB)
32
Silicon Vendor
Microchip
Pin count
40
RAM (Bytes)
2048
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 EasyAVR v8 as your development board.
Track your results in real time
Application Output
1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.
2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.
3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.
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
The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.
/*!
* @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 );
}
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
Additional Support
Resources
Category:Signal Processing
