Once we make a PSoC base-module, we can easily have, just by programming without soldering, various kinds of computer-controlled sensors such as a digital temperature sensor, a pH meter, or even a personal electrocardiogram (ECG). PSoC, a.k.a. mixed signal controller, is unique in the sense that it contains both analog and degital circuit-blocks configurable by programming. This feature greately simplifies electronic construction. PSoC is developed by Cypress.

As shown in the pictures, we actually constructed a digital thermometer and a pH meter. The add-on module connected to the base module only contains LM35 temperture-sensing IC, a buffer OP amp (LMC662CN in dual voltage follower configuration) and an EEPROM (data storage). A high-input-impedance op amp is needed for pH and ECG monitoring. The key switches are for selecting the programs.

The base module consists of PSoC, LCD display, MAX232, 5V regulator, switches and connectors. The circuit and its construction was fairly simple and straightforward. Thanks to PSoC the cost of this versatile base-module was very low. It is within the range of our pocket money!

The serial port is used for communicating with a host computer. If a serial-to-USB converter cable ($15 or more) is used, this device is connected through a USB port. Or, even a wireless connection is possible by using a serial Bluetooth modem.