Low-power 8 bits microcontroller

Question

For a personnal project, I intend to design a board with a temperature sensor, an MCU and a wireless "connector". I would like to have that board powered by battery. The wireless technology is not yet clear, but I am considering which MCU would be the most adapted?

I was considering the following characteristics:

• cheap,
• easy to place and to program,
• low-power (and probably some sleep mode built in),
• one 6-8 bits ADC,
• Some I²C and/or serial connection,
• one or more digital outputs to, e.g. light some LED.

The precision and speed are not decisive criteria, so proably an 8-bits MCU is perfectly fine.

Semi-conductors companies often provide some comparison tools but those are limited to their own products, like here, SiLabs. But I wanted to know if one/any of you had any experience in that respect, and would be able to recommand some MCU.

The Sleepy Bee or the MSP430L09x could be interesting, whereas the XLP seems overkill.

As it is a personal project, the compiler should not be too expensive, and ideally free.

Can anyone provide me any insight on that?

Answer 1

I would recommend the Arduino.

Arduino chips are absolutely the way to go! The Arduino MEGA uses the ATmega16U2 chip and meets all of your requirements. It can easily run on USB power or less.

Features
• High Performance, Low Power AVR® 8-Bit Microcontroller
• Advanced RISC Architecture
– 125 Powerful Instructions – Most Single Clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 16 MIPS Throughput at 16 MHz
• Non-volatile Program and Data Memories
– 8K/16K/32K Bytes of In-System Self-Programmable Flash
– 512/512/1024 EEPROM
– 512/512/1024 Internal SRAM
– Write/Erase Cycles: 10,000 Flash/ 100,000 EEPROM
– Data retention: 20 years at 85C/ 100 years at 25C(1)
– Optional Boot Code Section with Independent Lock Bits
In-System Programming by on-chip Boot Program hardware-activated after
reset
True Read-While-Write Operation
– Programming Lock for Software Security
• USB 2.0 Full-speed Device Module with Interrupt on Transfer Completion
– Complies fully with Universal Serial Bus Specification REV 2.0
– 48 MHz PLL for Full-speed Bus Operation : data transfer rates at 12 Mbit/s
– Fully independant 176 bytes USB DPRAM for endpoint memory allocation
– Endpoint 0 for Control Transfers: from 8 up to 64-bytes
– 4 Programmable Endpoints:
IN or Out Directions
Bulk, Interrupt and IsochronousTransfers
Programmable maximum packet size from 8 to 64 bytes
Programmable single or double buffer
– Suspend/Resume Interrupts
– Microcontroller reset on USB Bus Reset without detach
– USB Bus Disconnection on Microcontroller Request
• Peripheral Features
– One 8-bit Timer/Counters with Separate Prescaler and Compare Mode (two 8-bit
PWM channels)
– One 16-bit Timer/Counter with Separate Prescaler, Compare and Capture Mode
(three 8-bit PWM channels)
– USART with SPI master only mode and hardware flow control (RTS/CTS)
– Master/Slave SPI Serial Interface
– Programmable Watchdog Timer with Separate On-chip Oscillator
– On-chip Analog Comparator
– Interrupt and Wake-up on Pin Change
• On Chip Debug Interface (debugWIRE)
• Special Microcontroller Features
– Power-On Reset and Programmable Brown-out Detection
– Internal Calibrated Oscillator
– External and Internal Interrupt Sources
– Five Sleep Modes: Idle, Power-save, Power-down, Standby, and Extended Standby
• I/O and Packages
– 22 Programmable I/O Lines
– QFN32 (5x5mm) / TQFP32 packages
• Operating Voltages
– 2.7 - 5.5V
• Operating temperature
– Industrial (-40°C to +85°C)
• Maximum Frequency
– 8 MHz at 2.7V - Industrial range
– 16 MHz at 4.5V - Industrial range

Answer 2

The Arduino is probably one of the best options out there. Another board that you might find interesting is the SimpleLink Wi-FI CC3200 Launchpad. You can program the board via two ways, which are Code Composer Studio (CCS) by TI and Energia (which is basically an Arduino IDE fork). There is a MOD version of this board, but the only major difference is that some of the passives are integrated into a module (helpful if you plan to spin a PCB based on this MCU at a later stage).

Both of them are free to use, and depending on your background in embedded systems, you might find CCS rather helpful in fine tuning it to what you want. As for the sleep modes, I think you have 4 power modes to work with, so low power should not be a problem.

Links:

http://www.ti.com/tool/cc3200-launchxl

http://www.ti.com/product/cc3200

EDIT:

Sorry for not being more detailed on the MCU. Here are some of the highlights of this MCU:

ARM Cortex-M4 Core at 80 MHz - Embedded Memory Options

• Integrated Serial

• RAM (up to 256KB)

• Peripheral Drivers in ROM

• Hardware Crypto Engine for Advanced Hardware Security Including

• AES, DES, and 3DES

• SHA and MD5

• CRC and Checksum

• 8-Bit, Fast, Parallel Camera Interface

• 1 Multichannel Audio Serial Port (McASP)

Interface With Support for I2S Format

– 1 SD (MMC) Interface

– 32-Channel Micro Direct Memory Access (μDMA)

– 2 Universal Asynchronous Receivers/Transmitters (UARTs)

– 2 Serial Peripheral Interfaces (SPIs)

– 1 Inter-integrated Circuit (I2C)

– 4 General-Purpose Timers (GPTs)

– 16-Bit Pulse-Width Modulation (PWM) Mode

– 1 Watchdog Timer Module

– 4-Channel 12-Bit Analog-to-Digital Converters (ADCs) – Up to 25 Individually Programmable GPIO Pins

It is a 32 bit ARM processor, but it can definitely do pretty low power stuff. This is the datasheet for the CC3200MOD. http://www.ti.com/lit/ds/symlink/cc3200mod.pdf

Current consumption numbers are on page 27.