The PCF8591 is a monolithically integrated, and a separate power supply, low-power, 8-bit CMOS data acquisition devices. The PCF8591 has the four analog inputs, one analog output and a serial I2C bus interface. PCF8591 three address pins A0, A1 and A2 can be used in hardware address programmed 8 PCF..
The PCF8591 is a monolithically integrated, and a separate power supply, low-power, 8-bit CMOS data acquisition devices. The PCF8591 has the four analog inputs, one analog output and a serial I2C bus interface. PCF8591 three address pins A0, A1 and A2 can be used in hardware address programmed 8 PCF8591 device allows access to the same I2C bus, without the need for additional hardware. On the PCF8591 device input and output of the address, control and data signals are transmitted in serial fashion via the two-wire bidirectional I2C bus.
PCF8591 IC Features
Single power supply
PCF8591 operating voltage range of 2.5V-6V
Low standby current
Via I2C bus serial input / output
PCF8591 by 3 hardware address pins addressing
PCF8591 I2C bus speed sampling rate decided
4 analog inputs programmable single-ended or differential input
Automatic incremental channel selection
PCF8591 analog voltage range from VSS to VDD
PCF8591 built-in track-and-hold circuit
8-bit successive approximation A / D converter
1 analog output DAC gain
Module chip using PCF8951
Module supports external voltage input of the 4-way acquisition (voltage input range of 0-5v)
Module integrated thermistor by the precise value of the ambient temperature of the AD acquisition
Module integrated 1 channel 0-5V voltage input acquisition (the blue potentiometer to adjust the input voltage)
Modules with power indicator (for the module power supply indicator lights)
Modules with DA output indicator, when the module DA output interface voltage reaches a certain value, will be lit panel the DA output indicator, the higher the voltage, the more obvious indicator brightness;
Module PCB size: 3.6cm * 2.3cm
Standard double panel, thickness 1.6mm, nice layout, surrounded by a through-hole, aperture: 3mm, convenient fixed
Module interface specification
The module on the left and right, respectively, to expand outside the 2-way pin header, respectively, as follows:
AOUT chip DA output interface
AINO chip analog input interface 0
AIN1 chip analog input interface 1
AIN2 chip analog input interface 2
AIN3 chip analog input interface 3
SCL – IIC clock interface connected to microcontroller IO port
SDA – IIC digital interface connected to microcontroller IO port
P6 – connected to P6 shorting cap, select 0-5V adjustable voltage access circuit
The PCF8591 is a single-chip, single-supply low-power 8-bit CMOS data acquisition device with four analog inputs, one analog output and a serial I2C-bus interface. Three address pins A0, A1 and A2 are used for programming the hardware address, allowing the use of up to eight devices connected to the I2C-bus without additional hardware. Address, control and data to and from the device are transferred serially via the two-line bidirectional I2C-bus.
The functions of the device include analog input multiplexing, on-chip track and hold function, 8-bit analog-to-digital conversion and an 8-bit digital-to-analog conversion. The maximum conversion rate is given by the maximum speed of the I2C-bus.
-1 * Raspberry Pi
- 1 * Breadboard
- 1 * Network cable (or USB wireless network adapter)
- 1 * PCF8591 module
- 1 * Dual-Color LED module
- 1 * 3-Pin anti-reverse cable
- Several Jumper wires (M to F)
Each PCF8591 device in an I2C-bus system is activated by sending a valid address to the device. The address consists of a fixed part and a programmable part. The programmable part must be set according to the address pins A0, A1 and A2. The address always has to be sent as the first byte after the start condition in the I2C-bus protocol. The last bit of the address byte is the read/write-bit which sets the direction of the following data transfer (see the figure below).
The second byte sent to a PCF8591 device will be stored in its control register and is required to control the device function. The upper nibble of the control register is used for enabling the analog output, and for programming the analog inputs as single-ended or differential inputs. The lower nibble selects one of the analog input channels defined by the upper nibble (see Fig.5). If the auto-increment flag is set, the channel number is incremented automatically after each A/D conversion. See the figure below.
In this experiment, the AIN0 (Analog Input 0) port is used to receive analog signals from the potentiometer module, and AOUT (Analog Output) is used to output analog signals to the dual-color LED module so as to change the luminance of the LED.