ST, NXP 32-bit controller families issue call to ARM - Embedded.com

ST, NXP 32-bit controller families issue call to ARM

SUNNYVALE, Calif. — Expanding the potential applications range and support structure for the ARM architecture in advance of next week's ARM Developers' Conference in Santa Clara, Calif., STMicroelectronics and NXP Semiconductors have separately released 32-bit microcontroller families that take aim at industrial, consumer and other applications. Both companies based their designs on the ARM7TDMI CPU core, with STMicroelectronics' controllers clocking at 60 MHz and NXP's at 72 MHz.

ST's lineup
The STR750F family from STMicroelectronics includes 15 different versions, offering 64 to 256 kbytes of on-chip flash memory, 16 kbytes of read-while-write flash and 16 kbytes of SRAM, as well as a range of general-purpose I/O peripherals and USB and CAN interface options on some versions. The NXP LPC2300 series initially includes four devices, with 128 to 512 kbytes of flash and up to 58 kbytes of on-chip SRAM and I/O buffers, as well as a split dual-bus architecture to improve the efficiency of concurrent operations.

Able to deliver up to 54 Dhrystone Mips when clocked at 60 MHz, the SRT750F controllers come in compact 64- or 100-lead ball-grid array packages or 100-lead plastic quad flat packs. All versions come with a 10-bit A/D converter (3.75-microsecond/channel conversion time); a nested interrupt controller; and eight timers, including a 16-bit, six-channel pulse-width modulator that can be used to control three-phase motors. In addition to the typical scan mode, the A/D converter packs a novel mode that allows a specific channel to be inserted into the scan out of its typical sequence. Multiple communications ports are also included on the microcontrollers: an I2 C interface, three high-speed UARTS, two simple serial ports (up to 16 Mbits/second), one CAN port (2.0B active) and one USB full-speed (12-Mbit/s) port with eight configurable endpoint sizes.

The STR750F family also has various low-power standby modes that can drop current drain to as little as 10 microamps. An external power supply of either 3.3 or 5 V can power the chip, and an on-chip regulator keeps the internal power constant.

Starter kits are available from Hitex, IAR, Keil and Raisonance, and an evaluation board is available directly from STMicroelectronics. Low-level drivers are also available in ST's firmware library.

Pricing for the the lowest-cost chip, the STR755FRO, is $3.60 apiece in 10k lots, while the top-of-the-line STR750FV2 goes for $6.50 in similar quantities.

NXP's offerings
The NXP LPC2300 series includes a 10/100-Mbit/s Ethernet port (external PHY required) that can support two concurrent 100-Mbit/s data streams (for bidirectional data flow) with packet sizes of up to 1,500 bytes. The controllers also pack a full-speed USB 2.0 port capable of 12-Mbit/s data transfers, including an isochronous mode with 1,024-byte data bursts. Targeted at applications that need a higher level of data integrity, the controllers' flash memory includes error checking and correction. To get high-speed execution from the flash, designers employed a 128-bit-wide internal memory bus that allows multiple words to be transferred in a single cycle.

The 58 kbytes of on chip SRAM are split into several blocks—8 to 32 kbytes exclusively for the CPU, 16 kbytes for Ethernet buffering, 8 kbytes for USB port support, 2 kbytes of battery-backed storage for the real-time clock data support and 4 kbytes of storage for the USB FIFO buffer. A 32-source vectored interrupt controller and an emulation trace module for software debug are included on-chip. The split AHB buses on the chip allow high-speed and low-speed support functions each to have their own bus. That is said to prevent the low-speed peripheral functions from bogging down high-speed peripherals.

Like the STR family, the LPC2300 microcontrollers include CAN 2.0B support, albeit in the form of two channels (vs. one on the STR family). They also house four 16C550 type UARTs (compared with three on the STR devices), an eight-channel 10-bit A/D converter and a single 10-bit D/A converter. Four 32-bit general-purpose timers and a pulse-width-modulator block that supports three-phase motor control are on-chip. To minimize power consumption, a dc/dc converter on the chip regulates the external supply to 1.8 volts for all internal logic, except for the real-time clock logic, which includes a separate backup power input.

Software support in the form of TCP/IP stacks comes fron Interniche and Keil (now part of ARM), and NXP offers its own Ethernet device driver. A USB device driver is available from Keil or Micrium, and a CAN driver is available from Vector. Standard ARM JTAG interfaces allow all major ARM software tool chains to be used with the microcontrollers, and development boards are available from Keil and Nohau Systems.

The LPC2300 devices are in volume production now. Prices start at $3.99 apiece in lots of 10k units for the LPC2364 in a 100-lead QFP.

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