User Manual

Lesson 13 PCF8591

Introduction

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.

Components

- 1 * Raspberry Pi

- 1 * Breadboard

- 4 * Jumper wires (Male to Male)

- 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 (Male to Female)

Experimental Principle

Addressing:

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 as below).