Mindsensors PCF8574-Nx User Manual

What is PCF8574-Nx

PCF8574-Nx is a kit to interface 8-bit digital IO chip to NXT. It contains
all the basic parts needed along with general-purpose prototyping area on
the PCB. This kit can be used to design any custom sensor or IO device with
NXT. Following sections provide basic assembly instructions for this Kit.

PCF8574-Nx Feature List

• Uses NXT compatible I2C protocol for communications.

• All needed basic components included.

• Position for second NXT compatible socket that lets you connect the

multiple boards to same sensor port.

Connections

Can be connected to any four ports of NXT
by using standard NXT cables.

PCF8574-Nx V1.1User Guide

Tools you will need

All the electronic components needed for assembly are included. To
assemble these components, you will need a soldering iron, solder, pliers, and
wire cutter to cut the resistor and capacitor wires.

Assembly

Connect all the components as
shown on the PCB silkscreen. You
can connect NXT style socket
either to J1 or J2. You can use
the second jack to daisy chain the
boards. That way, you can connect
more than one sensor to single
NXT port. If you plan to do that,
ensure to use resistors R1 and R2
only on one board.

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Also ensure to select the correct
address by shorting the PCB
jumpers A0 A1 A2 at the bottom
of the board either on the lower
side (logic low) or the upper side
(logic Hi). e.g. Shorting A0, A1, A2
all to logic low will set the I2C
address of 0x40. For more details
on address selection refer to the
PCF8574 datasheets.

Programming Techniques for reading in I2C mode

NXT-G:

You can use the PCF8574-Nx with PCF8574-NX sensor block.
You can download this block from ‘Download’ section of
mindsensors.com website. (This requires Dynamic block
update patch installed on your NXT-G).

NOTE

Ensure to use LEGO firmware 1.05 on NXT while using NXT-G blocks.

RobotC:

You can use example program in C and robotC compiler to use PCF8574-Nx
on your NXT robot.

NBC:

You can use example program in NBC and NBC compiler to use PCF8574-Nx
on your NXT robot.

Robolab:

You can use example program and drivers Vi in Robolab 2.9 compiler to use
PCF8574-Nx on your NXT robot.

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