STMicroelectronics has announced a family of ARM Cortex-M3 based microcontrollers, claiming them to be the cheapest for the available performance.
“For sure we are offering more Mips for less money,” product marketing manager Frederic Gaillard told EW: “90 Dhrystone MIPS at zero wait state, 1.25DMips/MHz.”
The M3 core is ARM’s low-end Cortex, executing only Thumb-2 instructions. “It is really the next step after the ARM7TDMI, with 30 per cent more performance per MHz, or 75 per cent less power for the same processing.” said Gaillard.
Dubbed STM32, the family has been designed with battery operation in mind: operating from 2.0 to 3.6V, and needing only 2[micro]A in stand-by with reset circuitry active. An integrated 1.5[micro]A real-time clock (RTC) has its own coin cell supply and 32kHz crystal pins.
The core is capable of delivering 0.15mW/MHz. “Typical consumption is 36mA at 72MHz with the peripheral clock on, and 22mA if we disable all peripherals,” claimed Gaillard.
Within the family are 32 to 128kbyte flash options and 48 to 100pin packages with most standard peripherals.
Each memory-package combination comes in two types: an ‘access line’ version with a 36MHz ARM, up to 16kbyte SRAM and one 12bit 1[micro]s ADC; and a ‘performance line’ version with full 72MHz CPU, up to 20kbyte SRAM, two ADCs, a PWM timer and interfaces for USB and CAN.
10,000 unit prices range from $1.80 for 36MHz 32kbyte flash in a 48pin package, to $3.60 for 72MHz 128kbyte and 100 pins.
Luminary Micro has a $1.00 Cortex microcontroller. “It has 8kbyte of flash and no ADC,” said Gaillard. “It is positioned strongly against 8bit microcontrollers and that is not what we are doing.”
The access line is aimed at OEMs moving up from 16bit processors, with $200 development kits including hardware from IAR Systems, Keil, Hitex and Raisonance - all slated for the last quarter of this year and all allowing at least 16kbyte of C to be compiled without paying more. “There is also a GNU compiler for free,” said Gaillard.
With its six output PWM and twin ADCs, motor control is high on STM’s application list for the performance line.
“We have big customers for the part in motor control. We clearly defined the specification with these guys and the dual ADC is right for them,” said Gaillard, who also hinted that a triple simultaneous sampling part is under consideration. “We have also some requirement for an additional ADC and we will see what happens in the future.”