32-Bit Micro Still Handles 5 V For Harsh Environments

Sept. 17, 2013

Microcontroller operating voltages have been falling to reduce power and handle faster cores but 5-V operation is useful in harsh environments and this is where Freescale's 32-bit Kinetis E Series shines.

William G. Wong

Freescale’s Kinetis E series microcontrollers (Fig. 1) can handle 5-V applications with ease. The low-power, 32-bit Arm Cortex-M0+ architecture matches the Kinetis line but provides low-cost support for harsh environments with more demanding I/O requirements such as white goods, industrial products, and motor control applications. Operating from –40°C to 105°C, it is built using Freescale’s 180-nm technology.

Figure 1. The KE02 is based on the 32-bit Arm Cortex-M0+ core and each chip as its own unique 64-bit identifier.

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Each chip has a 5-V operating voltage (2.7 to 5.5 V) and I/O levels to minimize electromagnetic interference (EMI) and system-generated noise. The Cortex-M0+ has single-instruction bit manipulation support as well as single-cycle general-purpose I/O (GPIO) operations. High-current I/O ports allow direct connection to LEDs.

The family complies with IEC 61000-4-2 and 61000-4-4 standards. The development tools include certified IEC60730 Class B safety software routines. The chips are designed to reduce susceptibility to electrostatic discharge/electric fast transient (ESD/EFT) induced failures. This is important in meeting IEC 61000-4-2 and 61000-4-4 standard compliance where system reliability is key.

The 20-MHz ARM Cortex-M0+ core has a single-cycle 32-bit by 32-bit multiplier and cyclic redundancy checking (CRC) support. The family currently has parts with up to 64 kbytes of on-chip flash, 256 bytes of EEPROM, and 4 kbytes of RAM. The internal clock has 1% deviation from 0°C to 70°C and 1.5% deviation from –40°C to 105°C, up to 20 MHz.

Each chip has a 64-bit unique identification number. The analog support includes a 16-channel, 12-bit successive approximation register (SAR) analog-to-digital converter (ADC) with internal band gap reference channel. It can operate when the processor is in stop mode and there is an optional hardware trigger. The two analog comparators contain a 6-bit digital-to-analog converter (DAC) plus a programmable reference input.

Also, the chips include hardware fault detect pins to provide overvoltage and overcurrent protection. There is a real-time clock, a two-channel periodic interrupt timer, a watchdog timer, a six-channel FlexTimer/pulse-width modulator (PWM), and a pair of two-channel FlexTimer/PWM units.

Developers can evaluate the chips using the Freescale Freedom FRDM-KE02Z board (Fig. 2). It has a 20-MHz MKE02Z64VQH2 with 64 kbytes of flash and 4 kbytes of RAM in a 64-lead quad flat pack (64-QFP) package. The board also has an Infrared Data Association (IrDA) transmitter/receiver, a temperature thermistor, a capacative touch slider, and an MMA8451Q accelerometer. With its Arduino R3 form factor, it can be used with some Arduino expansion modules.

Figure 2. The Freescale Freedom FRDM-KE02Z board has a 20-MHz micro plus external features like an IrDA transmitter/receiver, capacitive touch slider, and MMA8451Q accelerometer.

Furthermore, the board uses Freescale’s OpenSDA, USB-based debug interface. The interface looks like a mass storage device that has demo apps as well as the debug interface. The USB port can provide power. Freescale’s Code Warrior development environment and Freescale’s free MQX real-time operating system support the board and chips.

The Kinetis E series is compatible with the ultra-low-power Kinetis L series. It also is pin-compatible with Freescale’s 8-bit S08Px and L series microcontrollers, giving 8-bit developers an upgrade path to the 32-bit Cortex-M0+ platform.