ADC 8 CLICK
PID: MIKROE-3394 Weight: 25 g
ADC 8 Click is a high precision, low-power, 16-bit analog-to-digital converter (ADC),
based around the ADS1115 IC. It is capable of sampling signals on four single-ended or
two differential input channels. Although the ADS1115 cannot use an external
reference, it incorporates a low-drift programmable voltage reference, along with the
programmable gain amplifier (PGA). This allows for great flexibility in terms of the input
signal level: it can sample signals from ±256 mV, up to 6.144 V, allowing a very high
precision for a wide range of input signals, making it an excellent choice for various
instrumentation applications.
ADC 8 Click is supported by a mikroSDK compliant library, which includes functions that
simplify software development. This Click board™ comes as a fully tested product,
ready to be used on a system equipped with the mikroBUS™ socket.
ADS1115 can operate either in continuous or in a single-shot mode. While operating in
a single-shot mode, the current consumption is significantly reduced, since the
ADS1115 powers down after each conversion. Its maximum sample rate in continuous
mode is up to 860 SPS. An overvoltage on the input can be detected and reported over
the ALERT pin. These features, along with the selectable operating voltage (3.3V or
5V), make the ADC 8 click perfectly suited for portable instrumentation applications,
battery voltage, and current monitoring, analog sensor output conversion, etc.
HOW DOES IT WORK?
The main component of ADC 8 click is the ADS1115 IC, an ultra-small, low-power, highprecision, 16-bit A/D converter, from Analog Devices. It is a delta-sigma converter with
an integrated high-precision voltage reference, which can be programmed in several
different steps. The maximum data rate of this ADC is 860 SPS, however, it features an
excellent signal-to-noise ratio (SNR). The ADS1115 has two differential or four singleended inputs. The internal multiplexer is used to select the active input. The input pins
are routed to two input terminals on the edge of the Click board™, allowing it to be
easily interfaced with the analog signal source.
Besides power supply pins and I2C interface pins, the ADS1115 has an additional
ALERT/RDY pin used to signal that there is a conversion data available on the output
register. This pin can also be set to output an overvoltage event. An internal comparator
module can detect if the input signal exceeds the voltage reference level and report the
overvoltage event at the ALERT/RDY pin. This pin is routed to the mikroBUS™ INT pin.
Both I2C pins along with the ALERT/RDY pin, are pulled to a HIGH logic level by the
pull-up resistors.
The conversion output is available over the I2C interface, in 16-bit two’s complement
LSB/MSB format. A positive input signal can have values in the range from 0x0001 to
0x7FFF, while the negative input signal can have values in the range from 0x0000 to
0x8000. The slave I2C address of the device can be selected by moving the SMD
jumper labeled as ADDR. It allows four different I2C addresses to be selected and thus,
up to four different ADC 8 clicks can be used on a single I2C bus.
Signal to Noise ratio (SNR) depends on two factors: the reference voltage and the
output data rate. Delta-sigma ADCs are based on the oversampling principle: the input
signal is sampled at a higher frequency and it is subsequently filtered and decimated,
until the output value is obtained, at the requested output data rate. The ratio between
the high sampling frequency (modulator) and the output data rate is called oversampling
ratio (OSR). By increasing the OSR, less noise appears at the output, since more
values are included in the averaging process.
As already mentioned, the ADS1115 IC cannot use an external voltage reference.
However, it has a high-precision internal reference with low drift over temperature. It can
be selected from several available values: ±0.256, ±0.512, ±1.024, ±2.048V, ±4.096,
and ±6.144. Note, however, that the input signal should not be greater than VCC +
0.3V. In other words, it is not possible to use the 4.096V if the power supply source is
3.3V. ADC 8 click is equipped with the SMD jumper labeled as VCC SEL, which allows
selection between 3.3V and 5V.
SPECIFICATIONS
Type
ADC
Applications
It is well suited for portable instrumentation applications, battery voltage, and
current monitoring, analog sensor output conversion, etc.
On-board
modules
ADS1115 IC, an ultra-small, low-power, high-precision, 16-bit A/D converter,
from Analog Devices.
Key Features
Analog to digital conversion from 4 single-ended channels or 2 differential
input channels, sampling resolution of 16 bits over the I2C interface,
programmable high-precision internal reference…
Interface
I2C
Input Voltage
3.3V or 5V
Click board
size
M (42.9 x 25.4 mm)
PINOUT DIAGRAM
This table shows how the pinout on ADC 8 Click corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
Notes
NC
1
AN
PWM
16
NC
NC
2
RST
INT
15
INT
NC
3
CS
RX
14
NC
NC
4
SCK
TX
13
NC
NC
5
MISO
SCL
12
SCL
I2C Clock
NC
6
MOSI
SDA
11
SDA
I2C Data
Power Supply
3V3
7
3.3V
5V
10
5V
Ground
GND
8
GND
GND
9
GND
Alert/Data Ready
Power supply
Ground
ONBOARD SETTINGS AND INDICATORS
Label
Name
Default
LD1
PWR
-
Description
Power LED indicator
JP1
VREF SEL
Left
JP2,
JP3
ADDR
Down
Power supply voltage selection, left position 3.3V,
right 5V
Slave I2C Address Selection
SOFTWARE SUPPORT
We provide a library for the ADC 8 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 contains functions for the complete communication of the MCU with click.
The user can use functions to read the ADC values and voltage on the channel. The
library also offers functions for writting data into the register and reading data from the
register, as well as the configuration of the device for successful measurement.
Key functions:
float adc8_getVoltage(uint8_t channel) - Read Voltage in mV
uint16_t adc8_getADCValue(uint8_t channel) - Get ADC value reads from the channel
void adc8_deviceConfig(uint16_t cfg) - Device configuration for measurement
Examples description
The application is composed of the three sections :
System Initialization - Initializes I2C module and sets INT pin as INPUT
Application Initialization - Initialization driver init and configuration device for measurement.
Application Task - Reads voltage from each channel one by one and the voltage difference between
specified channels
Note: On the input channel AIN0,AIN1,AIN2 and AIN3 sets maximum voltage GND ‐ 0.3V <
VIN > VDD + 0.3V.
void applicationTask()
{
// Single channel
vSingle_CH0 = adc8_getVoltage(_ADC8_SINGLE_CHANNEL_0);
vSingle_CH1 = adc8_getVoltage(_ADC8_SINGLE_CHANNEL_1);
vSingle_CH2 = adc8_getVoltage(_ADC8_SINGLE_CHANNEL_2);
vSingle_CH3 = adc8_getVoltage(_ADC8_SINGLE_CHANNEL_3);
mikrobus_logWrite("______________________________________________", _LOG_LINE);
mikrobus_logWrite(" Channel | CH 0 | CH 1 | CH 2 | CH 3 |", _LOG_LINE);
mikrobus_logWrite(" Single |", _LOG_TEXT);
IntToStr(vSingle_CH0, demoText);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" |", _LOG_TEXT);
IntToStr(vSingle_CH1, demoText);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" |", _LOG_TEXT);
IntToStr(vSingle_CH2, demoText);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" |", _LOG_TEXT);
IntToStr(vSingle_CH3, demoText);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" |", _LOG_LINE);
// Diff channel
vDiff_CH01 = adc8_getVoltage(_ADC8_DIFF_CHANNEL_0_1);
vDiff_CH03 = adc8_getVoltage(_ADC8_DIFF_CHANNEL_0_3);
vDiff_CH13 = adc8_getVoltage(_ADC8_DIFF_CHANNEL_1_3);
vDiff_CH23 = adc8_getVoltage(_ADC8_DIFF_CHANNEL_2_3);
mikrobus_logWrite("______________________________________________", _LOG_LINE);
mikrobus_logWrite(" Channel | CH 0‐1 | CH 0‐3 | CH 1‐3 | CH 2‐3 |", _LOG_LINE);
mikrobus_logWrite(" Diff |", _LOG_TEXT);
IntToStr(vDiff_CH01, demoText);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" |", _LOG_TEXT);
IntToStr(vDiff_CH03, demoText);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" |", _LOG_TEXT);
IntToStr(vDiff_CH13, demoText);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" |", _LOG_TEXT);
IntToStr(vDiff_CH23, demoText);
mikrobus_logWrite(demoText, _LOG_TEXT);
mikrobus_logWrite(" |", _LOG_LINE);
mikrobus_logWrite("|‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐|", _LOG_LINE);
Delay_1sec();
}
The full application code, and ready to use projects can be found on our LibStock page.
Other mikroE Libraries used in the example:
I2C
Conversions
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.
MIKROSDK
This click board is supported with mikroSDK - MikroElektronika Software Development
Kit. To ensure proper operation of mikroSDK compliant click board demo applications,
mikroSDK should be downloaded from the LibStock and installed for the compiler you
are using.
For more information about mikroSDK, visit the official page.
https://www.mikroe.com/adc‐8‐click/3‐21‐19