Low power USB Microcontroller

I wonder if anyone can help, I am looking for a USB Microcontroller with the following specifications

USB+USART+SPI , possibly not need SPI USB slow or fast, RS232-300-19200 baud min, prefer upto 115200. When the USB is in suspend or not connected Microcontroller needs to run at low speed such that current consumption is around 1mA but the RS232 to keep running and the data logged and no problems with switching crystal frequencies etc for the reduced current consumption requirements. Ram 1K Flash, 4K+USB Firmware. Does anybody know of anything that could do this? Thanks

Reply to
sjones
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The at43usb355 might work for you.

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Reply to
Ico

Sram or Masked ROM only, no flash. No UART. Not a good fit.

AT90USB162 might be better

16K flash, Uart, Spi, USB bootloader and apps.

If you need more than 512 bytes SRAM, then AT90USB646 (4K SRAM).

Reply to
linnix

Look at the Silicon Labs C8051F32x parts.

-a

Reply to
Andy Peters

Thanks, if I use the AT90USB162 which has a RC internal clock for the low power mode then if the USB link is unplugged we have maybe 10mS to switch to low power mode before we run out of power. It would seem to me that after switching clocks if the baud rate divisor is adjusted it shouldn't be a problem with any RS232 characters being received but perhaps I am missing something ?

Reply to
sjones

It should work in theory, but I have not tried switching from crystal to RC in run time. When USB is disconnected, my board switches from

8M (8 ma) to 1M (1 ma) clock and run from rechargeable battery anyway. The lowest crystal clock should meet your power budget, if you pull charges from the RS232 lines as well.
Reply to
linnix

On 7/10/2007 10:11 AM, The digits of snipped-for-privacy@scannex.co.uk's hands composed the following:

Cypress FX2 fits most of that, but needs external serial Flash, or firmware can be loaded from PC for no on board flash. Note the biggest drawback is only the larger FX2s have UARTS. For some crazy reason they left that off of most flavors of the FX2.

Hawker

Reply to
Hawker

You also need another interface to program the external flash. The AT90USBs can be bootloaded from internal flash via USB.

Costly as well. The Cypress FX2 (16K RAM) is priced in same range as the AT90USB1286 (128K FLASH, 8K RAM).

Reply to
linnix

I have just discovered that the buad rate register in the AT90USB162 has an associated down counter. The down counter is run at the system clock and is loaded with the contents of the baud rate register each time it reaches zero, or when the baud rate register is written to, hence it will not work. If I knew a RS232 character was in the process of coming in I could wait but there appears to be no status lag for this.

Reply to
sjones

Many AT90 parts have an input-capture pin, external timer trigger pin, or even just normal interrupt pins. You might be able to use one of these to learn about "in-flight" incoming characters.

Regards, Marc

Reply to
jetmarc

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