Experience seamless and dynamic sound control with PT2258 and ATmega32A
Unleash sonic perfection at your fingertips!
Published Jul 11, 2024
Click board™
EVC Click
Dev. board
EasyAVR v8
Compiler
NECTO Studio
MCU
ATmega32A
Discover a new level of audio quality and convenience with our six-channel digital volume controller, featuring an integrated electronic volume control circuit, designed to deliver sonic perfection with effortless control.
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Hardware Overview
How does it work?
EVC Click is based on the PT2258, a six-channel electronic volume controller from Princeton Technology. This IC contains six digitally controlled audio attenuators, which can attenuate signals between 0dB and -79dB. Each channel can be individually controlled by two-byte commands, sent over the I2C interface. Although digitally controlled, sound signals within the PT2258 remain in the analog domain. The PT2258 offers a very clear and undistorted sound. The Signal to Noise Ratio (SNR) of the PT2258 is specified to be 105dB (1V RMS at any input), while the Total Harmonic Distortion (THD) is only 0.005% (200mV RMS at any input). THD gets worse as the input signal rises: 2.8V RMS results in THD of 1%. The maximum input signal should stay below 2.8V, else too much audible distortion may appear at the output. The Click board™ is equipped with two rows of standard 2.54mm (100 mil) headers. There are six pins at each row, allowing the inputs and the outputs to be easily interfaced with the existing multichannel equipment. This Click board™ should be connected on the signal path,
either in front of the amplifier itself, or in front or behind other sound processing equipment (e.g. equalizer, delay, room correction, and more). That way, an optimal audio signal level will be ensured for the Click board™. Each input/output pair runs through an internal attenuator, which provides up to -79dB of attenuation, in 1dB steps. Although it seems like a very high attenuation, using it with amplifiers with high gain values may lead to still hear the sound, even after the full attenuation. Therefore, the PT2258 features a MUTE function, that completely cuts the audio output. To set attenuation of a certain level, two bytes must be consequently sent over the I2C interface. There are both -1dB step commands and -10dB step commands for each channel. To achieve the desired attenuation at the specific channel, two commands should be sent consequently: one for -10 dB attenuation, and one for -1 dB attenuation. These commands can be sent in any order. However, sending a single command or adding a MUTE command between two attenuation commands may lead to unpredictable results. This Click
board™ is supported by a mikroSDK compliant library of functions, which greatly accelerate software development, by simplifying the software development. The I2C slave address of the Click board™ can be set using two SMD jumpers, grouped under the I2C ADD label. First SMD jumper is labeled as C1, while the second jumper is labeled as C2. These jumpers are used to configure bits CODE1 and CODE2, allowing several different I2C addresses to be selected. These jumpers can be independently moved to either position, allowing to select the desired slave address. Please refer to the PT2258 datasheet for more information about configuring the I2C slave address. The Click board™ uses the I2C interface for the communication. It can be interfaced with both 3.3V and 5V microcontrollers (MCUs) by simply switching the SMD jumper labeled as VCC COMM to a desired position. However, thePT2258 itself still requires 5V for its operation, since it requires a power supply voltage between 5V and 9V.
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 EVC Click driver.
Key functions:
evc_set_volume_part- This function sets the volume for the selected channel, uses two variables.evc_set_volume_full- This function sets the volume for the selected channel, uses one volume variables.evc_mute- This function mute and unmute the sound.
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
* \brief EVC Click example
*
* # Description
* This application allows manipulation of 6 channel volume control
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialization driver init, default configuration and sets first volume.
*
* ## Application Task
* emulates user input and exectuyrd functions based on set of valid commands.
*
* *note:*
* Additional Functions :
*
* void test_change ( ) - Emulates user input to change parameters.
* void mute( ) - Mute nad
* void play ( ) - Start new settings of the cahnnel
* uint8_t get_current_channel ( ) - Return current channel.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "evc.h"
// ------------------------------------------------------------------ VARIABLES
static evc_t evc;
static log_t logger;
// ------------------------------------------------------- ADDITIONAL FUNCTIONS
uint8_t get_current_channel ( uint8_t ch )
{
if ( ch == 1 )
{
return EVC_CHANNEL_1;
}
if ( ch == 2 )
{
return EVC_CHANNEL_2;
}
if ( ch == 3 )
{
return EVC_CHANNEL_3;
}
if ( ch == 4 )
{
return EVC_CHANNEL_4;
}
if ( ch == 5 )
{
return EVC_CHANNEL_5;
}
if ( ch == 6 )
{
return EVC_CHANNEL_6;
}
return EVC_CHANNEL_1;
}
void play ( evc_t *ctx )
{
uint8_t current_channel;
if ( ( ctx->play_flag == 1 ) && ( ctx->mute_flag != 1 ) )
{
current_channel = get_current_channel( ctx->channel );
evc_set_volume_full( ctx, current_channel, ctx->volume );
log_printf( &logger, " Channel [ %d ] -- Volume [ %d ] \r\n", ctx->channel, ctx->volume );
ctx->play_flag = 0;
}
}
void mute( evc_t *ctx )
{
/* Mute and Unmute */
if ( ctx->mute_flag == 0 )
{
ctx->mute_flag = 1;
evc_mute( ctx, EVC_ALL_CHANNEL_MUTE );
log_printf( &logger, " All channels MUTE !!!\r\n" );
}
else
{
ctx->mute_flag = 0;
evc_mute( ctx, EVC_ALL_CHANNEL_UNMUTE );
log_printf( &logger, " All channels UNMUTE !!!\r\n" );
}
}
void test_change ( evc_t *ctx )
{
ctx->channel++;
if( ctx->channel > 6 )
{
ctx->channel = 6;
}
ctx->volume--;
if( ctx->volume < -79 )
{
ctx->volume = -79;
mute( ctx );
}
ctx->play_flag = 1;
Delay_ms ( 750 );
}
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
evc_cfg_t cfg;
/**
* 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.
evc_cfg_setup( &cfg );
EVC_MAP_MIKROBUS( cfg, MIKROBUS_1 );
evc_init( &evc, &cfg );
evc_default_cfg( &evc );
log_printf( &logger, " \\-/-\\-/ START EQUALIZER \\-/-\\-/ ");
}
void application_task ( void )
{
// Task implementation.
test_change( &evc );
play( &evc );
}
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
