Experience limitless PWM possibilities with PCA9685 and ATmega1284P
16 channels, 1 interface - Total PWM dominance
Published Nov 01, 2023
Click board™
PWM Click
Dev. board
EasyAVR v7
Compiler
NECTO Studio
MCU
ATmega1284P
This innovative solution offers seamless control of 16 PWM outputs through a single I2C interface, providing users with unmatched precision and versatility in managing their devices and applications
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Hardware Overview
How does it work?
PWM Click is based on the PCA9685, a fully programmable 16-channel PWM controller from NXP Semiconductors. Each output channel has a 12-bit resolution (4096 steps) fixed frequency individual PWM controller that operates at a programmable frequency from a typical 24Hz to 1526Hz with a duty cycle that is adjustable from 0% to 100%. All channels are set to the same PWM frequency. Although it is targeted toward driving LEDs, this Click board™ can also be used for other purposes, such as motor and industrial control, robotics, and similar applications that can benefit from having a compact 16-channel PWM driver. Each output channel can be turned OFF or ON, with no PWM control, or set at its individual PWM controller value, which minimizes current surges. The ON and OFF time delay is independently programmable for each of the 16 channels. The
output channels are programmed to be either open-drain with a 25mA current sink or totem poles with a 25mA sink and 10mA source capability at 5V. PWM Click communicates with an MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting Fast Mode Plus up to 1MHz. It also has a 7-bit slave address with the first four MSBs fixed to 1000. The slave address pins, A0, A1, and A2, are programmed by the user and determine the value of the three LSBs of the slave address. The value of these address pins can be set by positioning onboard SMD jumpers labeled as I2C ADR to an appropriate position marked as 0 or 1. It also possesses an additional enable signal, routed on the RST pin of the mikroBUS™ socket labeled EN, allowing asynchronous control of the output channels. It can also be used to set all the outputs
to a defined I2C- programmable logic state or externally ‘pulse width modulate’ the outputs. It is useful when software control requires multiple devices to be dimmed or blinked together. In addition, this Click board™ has two unpopulated headers through which up to seven additional PWM Click boards™ can be connected together. With the help of I2C ADR jumpers, it is possible to specify a different I2C address for each board, allowing 112 PWM outputs on a single I2C line. This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the PWR SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to 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 v7 is the seventh generation of AVR development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit AVR microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyAVR v7 allows you to connect accessory boards, sensors, and custom electronics more
efficiently than ever. Each part of the EasyAVR v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use a wide range of external power sources, including an external 12V power supply, 7-12V AC or 9-15V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B)
connector. Communication options such as USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets which cover a wide range of 16-bit AVR MCUs. EasyAVR v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development 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
AVR
MCU Memory (KB)
128
Silicon Vendor
Microchip
Pin count
40
RAM (Bytes)
16384
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 v7 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 PWM Click driver.
Key functions:
pwm_dev_config- Device configuration function.pwm_set_channel_raw- Set channel raw function.pwm_set_all_raw- Set all channels raw function.
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 PWM Click example
*
* # Description
* This is an example that shows the capability of PWM click.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initalizes I2C driver, enables output, configures device, sets prescaling,
* configures output and makes an initial log.
*
* ## Application Task
* Changes the duty cycle of all channels every 10 seconds.
* All data are being logged on USB UART where you can track their changes.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "pwm.h"
// ------------------------------------------------------------------ VARIABLES
static pwm_t pwm;
static log_t logger;
static uint8_t config0[ 6 ] = { 1, 0, 0, 0, 1, 0 };
static uint8_t config1[ 6 ] = { 1, 0, 0, 0, 0, 1 };
static uint8_t config2[ 4 ] = { 0, 1, 0, 0 };
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
pwm_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.
pwm_cfg_setup( &cfg );
PWM_MAP_MIKROBUS( cfg, MIKROBUS_1 );
pwm_init( &pwm, &cfg );
Delay_ms( 100 );
pwm_set_output( &pwm, PWM_ENABLE );
pwm_dev_config( &pwm, &config0 );
pwm_set_pre_scale( &pwm, 0x04 );
pwm_dev_config( &pwm, &config1 );
pwm_output_config( &pwm, &config2 );
Delay_ms( 100 );
log_printf( &logger, "--------------------------\r\n" );
log_printf( &logger, " PWM Click \r\n" );
log_printf( &logger, "--------------------------\r\n" );
}
void application_task ( void )
{
uint8_t chann_id;
pwm_set_all_raw( &pwm, PWM_MAX_RESOLUTION / 2 );
log_printf( &logger, "All Channels set to 50%% duty cycle \r\n" );
log_printf( &logger, "--------------------------\r\n" );
Delay_ms( 10000 );
for ( chann_id = 0; chann_id < 8; chann_id++ )
{
pwm_set_channel_raw( &pwm, chann_id, 0, PWM_MAX_RESOLUTION / 4 );
}
log_printf( &logger, "Channels 0-7 set to 25%% duty cycle \r\n" );
log_printf( &logger, "--------------------------\r\n" );
Delay_ms( 10000 );
for ( chann_id = 0; chann_id < 8; chann_id++ )
{
pwm_set_channel_raw( &pwm, chann_id, 0, ( PWM_MAX_RESOLUTION / 4 ) * 3 );
}
log_printf( &logger, "Channels 0-7 set to 75%% duty cycle \r\n" );
log_printf( &logger, "--------------------------\r\n" );
Delay_ms( 10000 );
pwm_all_chann_state( &pwm, 0 );
log_printf( &logger, "All Channels disabled \r\n " );
log_printf( &logger, "--------------------------\r\n" );
Delay_ms( 5000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
