Lpc2000

At 17:39 2004-02-20, you wrote:
>I just recieved 3 pieces of the LPC2214FBD144 (144 pin part) from
>philips as samples.  I was working on a rather complicated atmel
>AT91RM9200 design with all the bells and whistles, but since these
>parts arrived so quickly, I am considering putting that design on
>hold for a bit and getting something actually working by using the
>LPC2214.  Just to get something going, I am considering stripping my
>design down to the following:
>
>LPC2214FBD144
>2 channel 16 bit DAC on SPI #1
>8 channel 8 bit DAC on SPI #2

  If this is for your laser controller, I would recommend parallel DACs. 
You will have a bottleneck with SPI, and since you've got an external 
memory interface, use that.

>16 bit compact flash connector interface on the external memory
>controller

  For true-ide? What kinds of cards do you plan to support? You don't need 
the full CF bus for true-ide.

>RS485 level converter on UART0

  I guess this is for DMX512. Watch out for the break detection of the 
USART controller.

>RS232 level converter on UART1

  MIDI? Or just plain RS232?

>output buffers for DACS (+/-10 volts on the 16 bit DACS, 0-5 volts on
>the 8 bit, unless I find a 8 channel 8 bit dac with 0-5 volt buffers
>built in)

  What kind of inputs has your laser? 8-bit DACs are typically 
differential. The motor 16-bit DACs are usually both differential and bipolar.

  Have you considered an ILDA-compliant interface?

>Do you think this simple design is remotely possible on a 2 layer
>board?  I would love to keep it at two layers for cost reasons.

  *Too* risky. To get the most of the 16-bit DACs, a ground plane is a 
must. It saves a lot of headaches and layout time. Of course, always 
separate your analog circuits from your digital signals.

  Regards.