![\"Analog-to-digital](\"https:\/\/blog.seeedstudio.com\/wp-content\/uploads\/2020\/09\/Analog-to-digital-converter\u2014\u2014ADS1115-1030x579.png\")
<\/figure><\/div>\n\n\n\n\n\n\n\n
How do ADS1115 work?<\/h2>\n\n\n\n
ADS1115 has an onboard reference and oscillator. Data is transmitted through an I2C compatible serial interface; 4 I2C slave addresses can be selected. ADS1115 uses a single working power supply ranging from 2.0V to 5.5V.<\/p>\n\n\n\n
![\"\"](\"https:\/\/blog.seeedstudio.com\/wp-content\/uploads\/2020\/09\/Arduino-ADS1115-Module-Pin-Outs-Type-1.png\")
The ADS1115 can perform conversion operations at a rate of up to 860 samples per second (SPS). The ADS1115 has an onboard programmable gain amplifier (PGA) that can provide an input range as low as \u00b1256mV from the power supply voltage, thus enabling the measurement of large and small signals with high resolution. In addition, the ADS1115 also has an input multiplexer (MUX), which can provide 2 differential inputs or 4 single-ended inputs.<\/p>\n\n\n\n
ADS1115 can work in continuous conversion mode or single trigger mode, the latter will automatically power off after a conversion is completed, thereby greatly reducing the current consumption in the idle state. ADS1115 has a specified temperature range from -40\u00b0C to +125\u00b0C.<\/p>\n\n\n\n
\n\n\n\n
Pin function of ADS1115<\/h2>\n\n\n\n<\/div>\n\n\n\nPins<\/strong><\/td>Function<\/strong><\/td><\/tr>VDD<\/td> Power supply pin. Generally, the voltage difference between VDD and GND is 2-5.5V<\/td><\/tr> GND<\/td> Ground terminal<\/td><\/tr> ALERT<\/td> The result output of the comparator<\/td><\/tr> SCL, SDA<\/td> Communicate with other devices<\/td><\/tr> ADDR<\/td> Address side<\/td><\/tr> A0, A1, A2, A3<\/td> Input terminals<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<\/div>\n\n\n\nThe connection between ADS1115 and MCU<\/strong>:<\/p>\n\n\n\nVDD\u2014\u2014>3.3\/5V of MCU<\/p>\n\n\n\n
GND\u2014\u2014>SCM GND<\/p>\n\n\n\n
ADDR\u2014\u2014>Generally connected to ground<\/p>\n\n\n\n
A0-3\u2014\u2014>Connect to the input voltage line<\/p>\n\n\n\n
SCL, SDA -> SCL, SDA of the\nmicrocontroller<\/p>\n\n\n\n
ALERT\u2014\u2014>Dangling<\/p>\n\n\n\n
\n\n\n\nProduct features of ADS1115<\/h2>\n\n\n\n- Low power consumption: 150uA in continuous mode<\/li>
- Conversion rate: 8Bps to 860Bps<\/li>
- Internal oscillator<\/li>
- Built-in reference voltage: The internal reference voltage can be set by configuring the internal register.<\/li>
- IIC interface: Address can be programmed through pins, and there are typically three operating modes for communication frequency<\/li>
- ADS1115 supports the following 3 modes:
- Standard mode<\/strong>: Maximum 100KHz<\/li>
- Fast mode<\/strong>: maximum 400KHz<\/li>
- High-speed mode<\/strong>: up to 3.4MHz<\/li><\/ul><\/li><\/ul>\n\n\n\n<\/div>\n\n\n\n
- Four single-channel inputs or two differential inputs<\/li>
- Reference input positive and negative pressure: ADS1115 can collect positive and negative pressure.<\/li>
- Reference input positive pressure digital acquisition output range: 0-32767 (from small to large)<\/li>
- Reference input negative pressure digital acquisition output range: 32768-65535 (from small to large)<\/li><\/ul>\n\n\n\n
If the internal reference voltage of\nADS1115 is set to 4.096V, the positive voltage acquisition accuracy is\n4.096V\/2^15 = 0.125mV.<\/p>\n\n\n\n
- Initialization: ADS1115 related registers are initialized when power is on.<\/li>
- Operation mode: a single conversion and a continuous conversion.<\/li><\/ul>\n\n\n\n
\n\n\n\nADS1115 and IIC<\/h2>\n\n\n\n
ADS1115 data communication adopts IIC interface and follows the IIC communication protocol, so there are two operations to communicate with the single-chip microcomputer. One: The IIC communication protocol is simulated through the I\/O of the microcontroller to interact with it. Two: Use the microcontroller with the IIC interface to interact with it. In order to ensure the stability of the data exchange, the related steps should be configured strictly in accordance with the IIC protocol (start signal, stop signal, restart signal, response signal) and cannot be omitted.<\/p>\n\n\n\n
IIC is a half-duplex communication protocol\nthat can only receive or send at the same time.<\/p>\n\n\n\n
There are generally four kinds of signals: start signal, end signal, nck signal, nack signal.<\/p>\n\n\n\n
Read data<\/strong><\/p>\n\n\n\nReading data steps<\/p>\n\n\n\n
1. Generate IIC start signal<\/p>\n\n\n\n
2. Sending address<\/p>\n\n\n\n
3. Send a read operation command (2.3\ntogether into 8 bits)<\/p>\n\n\n\n
4. Wait for the response<\/p>\n\n\n\n
5. Read data<\/p>\n\n\n\n
6. Generate end signal<\/p>\n\n\n\n
<\/div>\n\n\n\nWrite data<\/strong><\/p>\n\n\n\n1. Generate IIC start signal<\/p>\n\n\n\n
2. Sending address<\/p>\n\n\n\n
3. Send the write operation command (2.3\ntogether into 8 bits)<\/p>\n\n\n\n
4. Wait for the response<\/p>\n\n\n\n
5. Write data<\/p>\n\n\n\n
6. Generate end signal<\/p>\n\n\n\n
\n\n\n\nRaspberry Pi uses ADS1115 module to read analog signals<\/h2>\n\n\n\n
Raspberry Pi is a common main control board\nwith powerful functions. The 16-bit AD conversion module of ADS1115 is\nspecially designed for Raspberry Pi and Gravity series analog sensors, which\ncan greatly reduce the difficulty of using analog sensors on the Raspberry Pi\nmain control board. It is plug-and-play and requires no soldering, which is\nvery convenient. The Gravity series of sensors are numerous and rich in types,\nwhich can meet the needs of various sensors for the Raspberry Pi main control\nboard.<\/p>\n\n\n\n
One AD module can read 4 channels of analog signals. Since the onboard I2C has an address selection switch function, it supports the cascading of 2 AD modules and reads 8 analog signal channels, which is sufficient to meet the needs of various scenarios.<\/p>\n\n\n\n
![\"\"](\"https:\/\/blog.seeedstudio.com\/wp-content\/uploads\/2020\/09\/9-19.png\")
Ref: Raspberry Pi uses ADS1115 <\/a><\/figcaption><\/figure><\/div>\n\n\n\nIn addition to the basic connection, our\nADDR interface also needs to be connected to the corresponding interface.<\/p>\n\n\n\n
Each device can use different address pin configurations to connect up to four ADS111x devices to a single I2C bus. Use the address pins to set the ADS111x to one of four different I2C addresses. Use GND, VDD and SCL addresses first. If using SDA as the device address, keep the SDA line for at least 100\u2002ns after the SCL line goes low to ensure that the device decodes the address correctly during I2C communication.<\/p>\n\n\n\n
Pins<\/strong><\/td>| Function<\/strong><\/td><\/tr> | VDD<\/td> | Power supply pin. Generally, the voltage difference between VDD and GND is 2-5.5V<\/td><\/tr> | GND<\/td> | Ground terminal<\/td><\/tr> | ALERT<\/td> | The result output of the comparator<\/td><\/tr> | SCL, SDA<\/td> | Communicate with other devices<\/td><\/tr> | ADDR<\/td> | Address side<\/td><\/tr> | A0, A1, A2, A3<\/td> | Input terminals<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n | <\/div>\n\n\n\n The connection between ADS1115 and MCU<\/strong>:<\/p>\n\n\n\n VDD\u2014\u2014>3.3\/5V of MCU<\/p>\n\n\n\n GND\u2014\u2014>SCM GND<\/p>\n\n\n\n ADDR\u2014\u2014>Generally connected to ground<\/p>\n\n\n\n A0-3\u2014\u2014>Connect to the input voltage line<\/p>\n\n\n\n SCL, SDA -> SCL, SDA of the\nmicrocontroller<\/p>\n\n\n\n ALERT\u2014\u2014>Dangling<\/p>\n\n\n\n If the internal reference voltage of\nADS1115 is set to 4.096V, the positive voltage acquisition accuracy is\n4.096V\/2^15 = 0.125mV.<\/p>\n\n\n\n ADS1115 data communication adopts IIC interface and follows the IIC communication protocol, so there are two operations to communicate with the single-chip microcomputer. One: The IIC communication protocol is simulated through the I\/O of the microcontroller to interact with it. Two: Use the microcontroller with the IIC interface to interact with it. In order to ensure the stability of the data exchange, the related steps should be configured strictly in accordance with the IIC protocol (start signal, stop signal, restart signal, response signal) and cannot be omitted.<\/p>\n\n\n\n IIC is a half-duplex communication protocol\nthat can only receive or send at the same time.<\/p>\n\n\n\n There are generally four kinds of signals: start signal, end signal, nck signal, nack signal.<\/p>\n\n\n\n Read data<\/strong><\/p>\n\n\n\n Reading data steps<\/p>\n\n\n\n 1. Generate IIC start signal<\/p>\n\n\n\n 2. Sending address<\/p>\n\n\n\n 3. Send a read operation command (2.3\ntogether into 8 bits)<\/p>\n\n\n\n 4. Wait for the response<\/p>\n\n\n\n 5. Read data<\/p>\n\n\n\n 6. Generate end signal<\/p>\n\n\n\n Write data<\/strong><\/p>\n\n\n\n 1. Generate IIC start signal<\/p>\n\n\n\n 2. Sending address<\/p>\n\n\n\n 3. Send the write operation command (2.3\ntogether into 8 bits)<\/p>\n\n\n\n 4. Wait for the response<\/p>\n\n\n\n 5. Write data<\/p>\n\n\n\n 6. Generate end signal<\/p>\n\n\n\n Raspberry Pi is a common main control board\nwith powerful functions. The 16-bit AD conversion module of ADS1115 is\nspecially designed for Raspberry Pi and Gravity series analog sensors, which\ncan greatly reduce the difficulty of using analog sensors on the Raspberry Pi\nmain control board. It is plug-and-play and requires no soldering, which is\nvery convenient. The Gravity series of sensors are numerous and rich in types,\nwhich can meet the needs of various sensors for the Raspberry Pi main control\nboard.<\/p>\n\n\n\n One AD module can read 4 channels of analog signals. Since the onboard I2C has an address selection switch function, it supports the cascading of 2 AD modules and reads 8 analog signal channels, which is sufficient to meet the needs of various scenarios.<\/p>\n\n\n\n In addition to the basic connection, our\nADDR interface also needs to be connected to the corresponding interface.<\/p>\n\n\n\n Each device can use different address pin configurations to connect up to four ADS111x devices to a single I2C bus. Use the address pins to set the ADS111x to one of four different I2C addresses. Use GND, VDD and SCL addresses first. If using SDA as the device address, keep the SDA line for at least 100\u2002ns after the SCL line goes low to ensure that the device decodes the address correctly during I2C communication.<\/p>\n\n\n\n |
![\"\"](\"https:\/\/blog.seeedstudio.com\/wp-content\/uploads\/2020\/09\/18_3.png\")