AudioAmp 4 Click
PID: MIKROE‐3271
Weight: 27 g
AudioAmp 4 click is a low-power audio amplifier with a digital volume control.
It is equipped with the LM4860, an audio amplifier IC capable of delivering
up to 1W of continuous power to an 8 Ω load. It has a very low total
harmonic distortion (THD) of less than 1% over the entire audio spectrum,
which makes it perfectly suited for small boom-boxes, PC speakers, and
similar low-power sound reinforcing devices that can be powered by
batteries. A high integration level of the LM4860 IC allows an additional
circuit for digital signal attenuation to be used, offering 8 different volume
levels, selectable over 3 GPIO pins of the mikroBUS™.
AudioAmp 4 click is supported by the mikroSDK compliant library, which
includes functions that simplify software development. The Click board™
comes as a fully tested product, ready to be used on a system equipped with
the mikroBUS™ slot.
In addition to the possibility to attenuate the input signal from the included
3.5mm JACK connector, AudioAMP 4 click can use analog voltage as the
amplifier input, derived from the PWM signal at the mikroBUS™ PWM pin.
This allows the MCU software to generate custom waveforms, by simply
changing the duty cycle of the PWM signal. Features such as the flat audio
characteristic, low THD and noise levels over the entire range of the audio
spectrum, digital volume control, power supply from the mikroBUS™ 5V rail,
make this Click board™ a perfect solution for rapid development of
applications, when a quick and simple low-power audio signal reinforcement
is required.
How does it work?
There are two integrated circuits on the AudioAMP 4 click: the LM4860, a
Boomer® series 1W audio power amplifier with shutdown mode;
CD74HC4051, a high-speed CMOS logic analog mux/demux IC, both
from Texas Instruments. The LM4860 is used as the main audio amplifier
component. This IC features a high level of integration, reducing the number
of external components to a minimum. It does not require any output
capacitors, bootstrap capacitors, or snubber circuits, which makes the design
very simple and straightforward.
Besides other functions, the IC features the Shutdown mode, activated by a
HIGH logic level on a dedicated SHUTDOWN pin. Therefore, to enable the
amplifier, this pin must be set to a LOW logic level. However, AudioAmp 4
click already has a pull-down resistor, so the audio amplifier IC is enabled by
default. The SHUTDOWN pin is routed to the CS pin of the mikroBUS™ and it
is labeled as EN. While in Shutdown mode, the power consumption is
minimized, which is very useful for applications that rely on a battery power
supply. The Shutdown mode pin is also routed to the #E pin of the
CD74HC4051, simultaneously disabling this IC as well.
The audio signal can be connected via the 3.5mm JACK connector. By
default, this signal is connected to one side of the voltage divider, composed
of eight resistors. The other end of the voltage divider is tied to the GND,
while the middle tap of the voltage divider can be selected by activating any
of the 8 available positions of the CD74HC4051 IC. The CD74HC4051 IC
uses three control pins, allowing its internal analog SP8T switch to be closed
between any of the eight I/O pins (A0 to A7), and one common I/O pin. The
audio signal goes through this divider, gets divided by the ratio selected with
the control pins, and into the audio input of the LM4860 audio amp IC. This
results in having eight discrete volume levels, which can be digitally selected
by S0 to S3 control pins routed to the mikroBUS™.
AudioAmp 4 click is equipped with the SMD jumper, labeled as IN SEL. This
jumper allows to select the output from the RC filter, which filters out the
PWM signal from the mikroBUS™ PWM pin, creating a DC signal of constant
voltage. By changing the pulse width of the PWM signal, the voltage output
of the RC filter will change. If the IN SEL switch is moved to the PWM
position, this signal will be introduced into the voltage divider, instead of the
audio signal from the 3.5mm JACK connector. It can be used to generate
custom waveforms by the software running on the host MCU.
Three control pins of the CD74HC4051 labeled as S0, S1, and S2, are routed
to the mikroBUS™ pins AN, RST, and INT, respectively, labeled according to
the names of the control pins. These pins accept logic HIGH and LOW levels
from the host MCU, so the CD74HC4051 can be controlled using a binary
format on the control pins.
The Click board™ uses only 5V rail from the mikroBUS™ and as such it
should not be interfaced with MCUs that have only 3.3V tolerant pins. The
complete control of the IC is done exclusively by GPIO pins of the MCU, so
the software development complexity is reduced to a minimum. However,
the click comes with the mikroSDK compliant library, offering a simple usage
example and functions for the rapid development of applications.
Specifications
Type
Amplifier
Applications
It can be used in various low power audio systems, home stereo
components, computer speakers, and many other similar audio
applications that require an audio amplification with the digitally
controlled volume level
On-board
modules
LM4860M, a Boomer® series 1W audio power amplifier with
shutdown mode; CD74HC4051, a high-speed CMOS logic analog
mux/demux IC, both from Texas Instruments
Key Features
High quality audio output up to 1W of continuous power, good
frequency response, low THD and SNR, it can be directly
implemented into the existing stereo system, digital volume
control.
Interface
GPIO,PWM
Input Voltage
5V
Click board
size
L (57.15 x 25.4 mm)
Pinout diagram
This table shows how the pinout on AudioAmp 4 Click corresponds to the
pinout on the mikroBUS™ socket (the latter shown in the two middle
columns).
Notes
Pin
Pin
Control pin 0
S0
1
AN
PWM
16
PWM
Control pin 1
S1
2
RST
INT
15
S2
Shutdown mode
enable
EN
3
CS
RX
14
NC
NC
4
SCK
TX
13
NC
NC
5
MISO
SCL
12
NC
NC
6
MOSI
SDA
11
NC
NC
7
3.3V
5V
10
5V
GND
8
GND
GND
9
GND
Ground
Notes
PWM signal
Input
Control pin 2
Power Supply
Ground
Onboard settings and indicators
Label
LD1
JP1
Name
Default
PWR
-
IN SEL
Left
Description
Power LED indicator
Input signal source selection: left position
3.5mm JACK, right position PWM pin of the
mikroBUS™
Software support
We provide a library for the AudioAmp 4 Click on our LibStock page, as well as
a demo application (example), developed using MikroElektronika compilers.
The demo can run on all the main MikroElektronika development boards.
Library Description
The library performs a audio control and works as audio amplifier. Possible
commands are to turn ON or OFF the output (speaker) and to set the output
volume by selecting the desired channel. For more details check
documentation.
Key functions:
T_AUDIOAMP4_RETVAL audioamp4_setChannel( uint8_t channel ) - Function performs a volume
T_AUDIOAMP4_RETVAL audioamp4_shutdown( uint8_t state ) - Function turns shutdown to ON
channel selection.
or OFF state.
Examples description
The application is composed of the three sections :
System Initialization - Initializes peripherals and pins.
Application Initialization - Initializes GPIO interface, turns shutdown OFF and performs a volume
channel 3 selection.
Application Task - (code snippet) - Checks which command is sent from uart and performs a
determined command. Note : Possible commands are:
Shutdown OFF
Shutdown ON l Legend 0-7 Volume channel selection
void applicationTask()
{
rxDat = UART_Rdy_Ptr();
if (rxDat != _NO_RECEIVED_DATA)
{
rxDat = UART_Rd_Ptr();
if (rxDat == '+')
{
audioamp4_shutdown( _AUDIOAMP4_SHUTDOWN_OFF );
mikrobus_logWrite( "* Shutdown OFF *", _LOG_LINE );
}
else if (rxDat == '‐')
{
audioamp4_shutdown( _AUDIOAMP4_SHUTDOWN_ON );
mikrobus_logWrite( "* Shutdown ON *", _LOG_LINE );
}
else if (rxDat == 'l')
{
writeLegend();
}
else
{
channSel = rxDat ‐ '0';
responseCheck = audioamp4_setChannel( channSel );
checkResponse();
}
}
}
Additional Functions :
void checkResponse() - Checks is channel selection parametar valid or not.
void writeLegend() - Writes the all possible commands on uart.
The full application code, and ready to use projects can be found on
our LibStock page.
Other mikroE Libraries used in the example:
UART
Additional notes and informations
Depending on the development board you are using, you may need USB UART
click, USB UART 2 click or RS232 click to connect to your PC, for development
systems with no UART to USB interface available on the board. The terminal
available in all MikroElektronika compilers, or any other terminal application
of your choice, can be used to read the message.
https://www.mikroe.com/audioamp‐4‐click/2‐13‐19