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Freescale’s “controller continuum” eases 8-32bit move

Pin-, peripheral- and code-compatible parts link 08 and Coldfire series

26th June 2007 – If you are engaged in microcontroller design and contemplating moving from the 8- to the 32-bit environment, Freescale has a new offering for you. As a bridging product range linking its S08 8-bit and Coldfire 32-bit architectures it has created its Flexis concept; Flexis parts will exist in both series of MCUs and will offer pin-for-pin, fit-and-function interchangeability, and will operate from the same C-code recompiled for the appropriate target. You will therefore be able to upgrade product designs, or use a common hardware platform for a range of products with different performances, using either 8- or 32-bit engines. To further simplify the 8/32-bit transition, Flexis chips have common peripheral sets and development tool environments.
The Coldfire core in Flexis is the V1 variant; at the same time, Freescal ahs extended the memory range of the S08 core to 128 kbytes. The first parts in the Flexis series have the additional identifier “QE”, as low-power devices: there will be further variants with USB interfaces, LCD drivers and CAN/Ethernet ports, to be introduced at a later stage. They are both 50-MHz parts although the 8-bit devices run at 25 MHz bus speed internally; operation is from 1.8 to 3.6V for battery power. SRAM is up to 8 kbytes and among the peripherals there is a range of standard interfaces plus 16-bit timers and a 12-bit 24-channelADC. Clocking can be internal or external. The low-power S08 core comes in a variety of memory sizes and package options down to 32 pins: direct compatibility with the Coldfire chip applies in two packages, 64 and 80 pins, MCF51QE128 for the Coldfire chip and MC9S08QE128 for the 8-bit. Running at 50 MHz the 32-bit part uses 27 mA, and the 8-bit, 11 mA: in low-power mode on an internal 32 kHz oscillator the figures are 50 and 22 μA: and there is a choice of stop modes that take current to 0.5 μA or less. Wake-up time, key in shortenting the on-time of low-duty-cycle operations, is 6 μsec. Pricing is also structured to ease the transition; at 10,000 quantity, the 64-pin parts cost $3.59 (S08) and $3.80 (CFV1).
Re-compiling your code and switching from the 8- to 32-bit device bring an approximately 10-fold increase in performance, according to Freescale’s European MCU product manager Jim Stuart, who also points out that many applications that are stretching 8-bit capabilities need 16-bit arithmetic: most applications are not written for pure a pure 8-bit environment. “A lot of code isn’t optimised for 8-bit and will run much better on a 32-bit machine,” Stuart says. Code development is in the CodeWarrior environment: the latest V.6 version allows up to 32k code size to be created in the free downloadable “special edition”, or up to 64k in the case of the Flexis Coldfire core. The 32k limit covers half of the total S08 range, Stuart says. A demonstration/basic development board costs $99, while a full evaluation board costs $325. You can also compile and debug code with no tool base at all, using an on-line “virtual lab” facility. The company will also host a series of training seminars around Europe in the coming months. Customers of distributor Future Electronics will also have access to that company’s Crossbow development board in its FutureBlox range.
Freescale’s market research, “told us that engineers needed an easier migration path from 8 to 32 bits: the current jump is too difficult, [with barriers in the areas of] IP and software investment,” Stuart says, adding, “there is a lot of good product in the low-end 32-bit market out there: by providing ease of migration we aim to keep users within the Freescale device family.”