In my last post I had indicated that TI MSP430 microcontrollers are good for ultra low power applications. The mix of resources on board the microcontroller makes it a desirable choice in mixed signal precision designs. Let's take a quick look at these on-board resources and peripherals that make it useful in such designs. As I have pointed out in my earlier post on the MSP430, these micro-controllers include varying amounts of a combination of on board ROM/OTP, Flash and RAM memories and LCD controllers. By including useful 8/16 bit peripherals the chip designers have achieved devices that can provide a single chip solution + a LCD quite often.

The kind of peripherals these microcontrollers contain include analog (ADC & DAC), digital serial communication resources, hardware multipliers, timers, watch dog timers, digital I/O etc. All of these are backed by a flexible yet well structured interrupt control mechanism. A 16 bit RISC CPU is in overall control along with power & clock management functions to keep power consumption at a minimum.

The analog peripherals are quite sophisticated. SD16 and SD16a type peripherals are full-fledged data acquisition systems by themselves. These have multiple channels, each of which can take on 8 pairs of inputs. Being differential, these inputs are ideal for low noise measurements of low signals. Typically on set is connected to a internal temperature sensor and the second one has the inputs shorted as calibration help to the other set of inputs. When present, there can 3 channels or 7 channel set up, backed by a 16 bit ADC. On conversion complete, interrupt is raised and the result is stored in specific memory locations(refer to the memory map in the earlier post). There are several methods available for measuring the inputs; simultaneously or in a sequence, on individual input or all of them. ADC 12 and ADC 10 resources are 12 bit and 10 bit devices for situations where the 16 bit precision is not required. These sense up to 16 inputs via sample and hold mechanism. Individual op amps ( up to 3 in a device) make implementation of comparators or low noise preamps easier.

DAC 12 devices are digital to analog converters that can be configured 8 or 12 bit operation and a device may have more than one such device.

The Universal synchronous/asynchronous receiver and transmitter or USART devices has a asynchronous UART mode as well as synchronous peripheral interface SPI mode. The UART and the SPI operate much as the most such devices. There's a I2C or the inter IC communication mode that can support this protocol. It also has a multi-processor communication mode.

The watchdog 16 bit timer can also be used as an interval timer. There's a enhanced watch dog timer or WDT+ that can be clocked. This clock cannot be disabled in the watchdog mode ensure the watch dog operates always.

Basic Timer1 is two cascadable 8 bit timers. It supports LCD display timings requirement and can be used as a real time clock or RTC. The RTC module whenever available on board supports 32 bit counting and counts seconds, minutes, hours, day of week, day of month, month and year in calendar mode. BCD mode can be selected. Timer A and Timer B are two 16 bit counters with multiple capture/compare registers. Timer B has a PWM in addition.

All these sophisticated resources make these devices suitable for precision mixed signal systems.

Read and download Texas Instruments datasheet