Electronic Design
Cortex-M4 Mixes With FlexMemory

Cortex-M4 Mixes With FlexMemory

Freescale's new Kinetis product line (Fig. 1) is built around ARM's 32-bit Cortex-M4 digital signal controller architecture. The line also takes advantage of Freescale's 90nm technology and its new Thin Film Storage (TFS) that is implemented using Freescale's FlexMemory architecture. The family ranges from the low power K10 to the high performance K70 incorporating a common peripheral set (Fig. 2).

The FlexMemory allows designers to select how flash memory is split between program and data storage. It also has EEPROM capability. TFS allows full operation at 1.71V and the memory has a read access time under 30ns.

Kinetis Line

The Kinetis line is based on the new Cortex-M4 that is compatible with teh Cortex-M3. The M4 adds digital signal controller (DSC) features a single cycle, 32-bit MAC. It also adds SIMD and DSP instructions and can include a single precision floating point unit (FPU). The Kinetis line takes advantage of these features eliminating items such as the FPU in lower end products.

Kinetis line is also linked together by a common peripheral set. One the analog side there is the 16-bit ADCs and 12-bit DACs. The chips also have programmable gain amplifiers and comparators. On the digital side, there is the 32-channel DMA that is linked to the crossbar switch. The usual serial interfaces like UARTs, I2C, SPI, and IIS are available along with timers and PWM support. The optional communication interfaces include CAN and Ethernet. Of course, there is plenty of digital I/O.

The Kinetis line starts with the low power K10/20 (Fig. 3). The chips are available in speeds up to 150MHz and they include the FPU and dual CAN interfaces. They forego USB, Ethernet and encryption support targeting low power, low cost embedded applications.

The mid-range 100MHz K30 and K40 (Fig. 4) adds LCD support making them ideal for mid-range human interface applications. They also have the dual CAN support with USB OTG available in the K40 line. The low power requirements make them ideal for mobile applications. K50 includes Ethernet support instead of CAN but retains the LCD support.

The high end K60 and K70 (Fig. 5) include everything from Ethernet to CAN along with high speed USB and OTG USB. The K60 skips the LCD support. Hardware tamper detection and hardware encryption support mark these chips for secure applications. They also have a NAND flash controller for external memory support.

The Kinetis line benifits from the ARM debug and trace support. This includes the embedded trace module (ETM).

FlexMemory Architecture

Freescale’s FlexMemory architecture (Fig. 6) was introduced as the same time as the Thin Film Storage (TFS) flash memory technology. The two are intertwined but distinct aspects of Freescale's storage support in the Kinetis line. The TFS is based on the new 90nm technology. It employs a split-gate for storage and it can operate at 1.71V while delivering access times under 30ns. It also provides improved bit-level reliability using Freescale's silicon nanocrystal technology.

FlexMemory is a partitioning system that allows a developer to specify how the flash array will be split between program and data storage. In general, a Freescale chip will have a large program flash and a smaller FlexMemory block. The latter can be divided into program storage or FlexNVM storage. The FlexRAM is an SRAM block that front ends the FlexMemory storage providing performance advantages. FlexMemory is independent of the main program flash allowing both to be accessed simultaneously.

FlexMemory EEPROM allows a trade off in data storage between size and endurance in excess of one million cycles. The Erase/Write times are 1.5ms that is five times faster than typical EEPROM implementations.

Development Tools

Freescale has extended its impressive suite of in-house and 3rd party development tools. This include support from development vendors like IAR and Keil.

The Freescale Microcontroller Enablement Bundle includes the MQX RTOS operating system, the Eclipse-based CodeWarrior 10.0 IDE, and the Freescale Tower (Fig. 7) hardware development platform. There is a growing open source and third party community, TowerGeeks.org.

The Freescale Tower architecture is actually being utilized by most and eventually all of the microcontrollers provided by Freescale. The modular architecture allows low cost peripheral boards to be plugged into the system for rapid prototyping. It is based on a stacking system that uses low cost PCI Express connectors although the microcontrollers do not utilize PCI Express.



TAGS: Freescale
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