2011-02-13

Texas Instruments has more than doubled the number of MSP430G2xxx versions with the release of 14 new parts. The new versions add special hardware to support capacitive-touch inputs on the MSP430G2xx2 devices. The capacitive-touch capability comes as an addition on some parts to the 10-bit A/D converter, a 16-bit timer with two or three capture-compare registers and the synchronous communications module.

This announcement is significant because of the price of these devices. These parts are priced to compete with low-end 8-bit 8051 and Microchip PIC12/16 devices. At the low-end, the MSP430G2001 sells at $0.34 in 1K quantities and has 512 of Flash, 128 bytes of RAM, and just the Watchdog and a 16-bit Timer. The mid-range MSP430G2231 has 2K of flash, 128 bytes of RAM, the Watchdog and the 16-bit Timer plus the synchronous serial communications module and the 10-bit A/D converter for the mid-range price of $0.55 in 1K quantities. A high-end part with 8K of flash, 256 bytes of RAM, capacitive-touch inputs, the Watchdog and 16-bit timer plus the synchronous serial communications module and the 10-bit A/D converter is priced at just $0.70 in 1K quantities. When compared with similarly priced 8-bit parts, the MSP430G2xx series will both run faster and provide longer battery life.

What is amazing is the number of interesting devices that can be built using one of these inexpensive microcontrollers, two AAA batteries and a few external components.

• With just an MSP430G2111, a sensor and an alarm, you can create an over-temperature indicator for the freezer, a low-temperature warning for the basement water pipes, a leak detector, or a CO detector.

• Add a relay to the previous design and you can control a simple heater for the basement.

• Use an MSP430G2131, an analog sensor, and a low-cost, serial EEPROM to build a temperature or humidity logger. (Use the special abilities of Timer A to create a soft UART to a PC.)

• You may build a simple alarm clock with an MSP430G2212, a couple of capacitance push-buttons, a numeric LCD with serial interface, and a piezoelectric buzzer.

• Using an MSP430G2332 capacitive touch buttons, a temperature sensor, two-relays and a serial alphanumeric LCD, you have a very flexible home thermostat.

• You can even create a portable digital FM radio with an MSP430G2302, capacitive touch buttons, a serial LCD, one of the single-chip FM receivers and a speaker circuit.

Perhaps more important, low-cost microcontrollers such as the MSP430G2xxx also make useful peripheral or specialty interface devices in larger projects. Just as PLDs (Programmable Logic Devices) and eventually FPGAs (Field Programmable Gate Arrays) replaced the catalog of logic devices that used to be sold in the millions; these low-cost microcontrollers pre-programmed for specific functions will eventually replace most of the specialty peripheral devices. The following useful peripherals can be implemented using one of the MSP430G2xxx devices.

• A custom touch keypad debouncer and FIFO queue with serial interface using an MSP430G2112

• A capacitive-touch keys input multiplexer

• A security code processor that enables "locked" hardware with an electrical signal after processing a multi-byte challenge code

• A simple stepper-motor acceleration-deceleration profile from serial commands using an MSP430G3202

• A battery-backed quadrature-encoder that maintains absolute position even when power is removed

Cooperating microcontrollers do not suffer from the performance overhead of coordinating multiple tasks on a single, faster microcontroller. This further improves the design of larger boards.