Help to choose a new MCU

Take a strong look at the LPC1768 from NXP. This part is about half the price for the '2468 and is available in a package that is more to your liking. Here is the summary feature list:

- ARM Cortex-M3 up to 100 MHz

- Nested Vectored Interrupt Controller

- 512 kB on-chip flash

- ISP and IAP support via bootloader

- 32kB of SRAM local to CPU

- Two 16 kB SRAM blocks for high performance I/O

- Eight channel DMA controller

- Split bus allows high throughput between the CPU and DMA.

- Ethernet MAC with RMII interface

- USB 2.0 full-speed device/Host/OTG controller

- Four UARTs with baud rate generation

- CAN 2.0B controller with two channels

- SPI controller

- Two SSP controllers with multi-protocol support

- Three enhanced I2C bus interfaces

- I2S (Inter-IC Sound) interface for digital audio i/o

- 70 General Purpose I/O

- 12-bit Eight channel ADC

- 10-bit DAC with timer and DMA

- Four general purpose timers/counters

- One motor control PWM with /three-phase motor support

- Quadrature encoder interface

- One standard PWM/timer

- RTC with a dedicated RTC oscillator

- 20 bytes of battery-powered backup registers

- WatchDog Timer

- ARM Cortex-M3 system tick timer

- Repetitive interrupt timer

- JTAG test/debug interface

- Emulation trace module

- Integrated Power Management Unit

- Low power modes: Sleep, Deep-sleep, Power-down, and Deep power-down

- Single 3.3 V power supply

- Four external interrupt inputs

- Non-maskable Interrupt

- Sys Clock output function

- Wake-up Interrupt Controller

- Brownout detector

- Power-On Reset

- Crystal oscillator 1 MHz to 25 MHz.

- 4 MHz internal RC oscillator / 1 % accuracy

- USB PLL

- Code Read Protection security

- Unique device serial number for ID

- Available 100-pin LQFP package

Way more capable than that ATMega128 and not so much more price.

--
Michael Karas
Carousel Design Solutions
http://www.carousel-design.com

Note that the LPC1768 doesn't have an external RAM interface as requested by the OP. However, the newer LPC177x MCUs do have an external memory controller. These are currently in development so might not be suitable if needed in a hurry:

-- Chris Burrows CFB Software Astrobe: LPC2xxx Oberon-07 Development System

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More processering power than you need, but a Blackfin BF516F will meet your requirements and is less expensive than the LPC2468.

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Some of the Luminary Micro/TI Stellaris ARM have an External Peripheral Interface for the SRAM, and will meet all of the requirments except flash size. If you can get by with less, the LM3S9B90 has 256KB, and the LM3S9790 has 128KB, a few others would also work. It's easy to find and compare them with the online selector guide:

Best regards,

Aaron

I'm curious - why these two requirements together with low cost, since they all fight? External memory bus adds a lot of pins that are then unusable as GPIO. The cost sweet spot is found in all-in-one chips.

So, how much SRAM do your designs need, or is it really that you are using memory-mapped I/O? If you are using SRAM for instance to store the "virtual tape" before sorting and printing at the end of an order, could you not use an external serial flash device instead?

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Look at the higher end parts, i.e. Microchip PIC18F97J60. No USB but it meets the rest of your requirements, including Ethernet and up to 128KBytes Flash. There may be more flash on later parts.

The new RX/62N from Renesas has all that, but it might be a bit pricey...

144-TQFP USB host, device, or OTG (pick one) Ethernet (MII/RMII) External addr/data bus External SDRAM interface 6 UART/SPI modules 512K flash, 96K internal RAM 8 12-bit ADC plus two 10-bit DAC 100 MHz core, 50 MHz bus Supported by GCC

If you can live with SPI-based ethernet, the M16C/6C family might be a more cost-sensitive option:

I don't think those are available yet, are they?

I know you can register to receive an RX62N RDK when it's released (by registering for a free RX610).

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Aaron

pricey...

Thanks for the reply guys. After a short research I am going towards NXP1778 or Luminary micro LM3S9B90.

They are both more than enough for my application. LPC's strong point is that I am already familiar with LPC series but it seems that it is still under development.

Luminary micro is completely new for me. I like its complete ethernet module (MAC + PHY !!). This gives this device a serious cost advantage because you dont need PHY. The 5V tolerant I/O its also a plus for me. Also I saw that LM3S has a ROM device driver library - I am wondering if its supported by IAR tools.

Does anyone of you guys have any hands on experience with this device ? What about its price (for 3-5K) and availability.

Thanks in advance.

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I haven't used it but there is an IAR tools version of the eval kit for this device for $99.

It looks available now and under $8 in 1k.

I would have a conversation with TI to find out more on that.

Aaron

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You can get samples from FEs if you ask, I think.