LabWorX (109033-2)

This board belongs with the book LabWorX 1 - Mastering the I2C Bus

This board complements board #1 and o­ ers even more modules with various functions. Some modules, like the protected input and output, are repeated. The idea is to make the I/O robust so it will survive experimentation on the bench. In a typical I2C implementation there are only a few memories or special functions while I/O remains the main application. Just like its counterpart this board is a panel with breakaway tabs. You can simply ‘snap’ the individual modules apart. The bus connector is present twice for every module. In this way you can simply click together the sub units of interest and try out your bus configuration before you make your own board. Every module has solder bridges that let you program the address of the devices on the unit. Devices that have interrupt capability can be connected, or left disconnected, from the interrupt line.

The board has the following sub modules:

PCA 9534 Protected Input

The protected input module features a PCA9534 device and has 8 inputs that can withstand up to 24 volts. The inputs are NOT opto isolated. Each input has its own LED indicating input state. The PCA9534 was chosen over the classic PCF8574 because it features mask registers and a, pin by pin, programmable input polarity. Connections to the board use a screw terminal block.

PCF8574 I/O Board

This is a simple I/O board that has no additional drivers or input protection. It can handle a variety of I/O chips such as the PCF8574, PCF8574A, PCA9534, PCA9554 and a few more. As usual, device addresses and interrupt capability may be set by solder bridges.

SAA1064 LED Display

The SAA1064 is an I2C compatible chip that can drive up to 32 individual LEDs. LED drive current is software controlled. In this module the SAA1064 is set up to drive four 7-segment displays. Ideal to display a numerical value that needs to be visible from a distance.

PCA9544 Bus Expander

The PCA9544 bus expander allows you to partition an I2C bus. Think of it as a router. Just like in a computer network, this device can combine multiple I2C buses into one. If you run out of address space in one branch, simply continue in the other branch.

ADC121 A/D Converter

This module contains a 12 bit A/D converter in SOT23 package. Multiple devices can share the bus. These are ideal to scatter around a system since you can get the precise signal digitized on the spot and don’t have to carry it far.

MCP4725 D/A Converter

This forms the counterpart to the 12 bit A/D module. It has 12 bit DACs in a SOT23 package. This module lets you play with these interesting devices.

LM75 Temperature Sensor

The LM75 temperature sensor is an all in one temperature sensor and monitor. It can be programmed to transmit a logic signal when certain, user specified, thresholds are exceeded. This board allows for the easy integration of this sensor in your I2C bus system.

PCA 9534 Protected Output

The protected output is the counterpart to the Protected Input board. It has an 8 channel output through an ULN2803 device. The controller, just like the protected input, is also a PCA9534. Off­ board connections are through a screw terminal block.

PCF8591 AD/DA

The PCF8591 is one of the oldest I2C devices out there, but it is still a very useful device. It combines a 4 channel 8 bit analog input with an 8 bit analog output. An instrumentation system allows the inputs to be set up as either single ended or di­fferential.

MCP40D17 Potentiometer

This module contains a programmable resistor. Through the I2C bus you. Can set the wiper value. Depending on the chip installed, this value can also be saved in EEPROM to be automatically restored on power up.

24xxx EEPROM Module

The EEPROM module can host any of the 24Cxx or 24cxxx devices as well as the PCF8581 and PCF8582 EEPROMs. For devices that have this capability, the board has a bridge to block write access to the memory array.

More: 

I2C PCB 1, bare