[Cryptech Tech] Alpha board block diagram v0.001

[Павел Шатов]

On 19.03.2015 17:22, Joachim Strömbergson wrote:
> Aloha!
>
> Here is the PDF version of the alha board block diagram. Please look at
> it and send feedback.
>
> I will put the source and latest PDF in the repo and add a link on the wiki.

My feedback is below.

1. Power Supply

12V seems reasonable. End users will have to buy a cheap wall adapter, 
something like 
http://powerzi.eu/12v-1a-european-wall-plugin-type-adapter-p-81.html

The only question is total current consumption of Alpha. In his manual 
Bunnie says that 12V/3A adapter is required for Novena. We will have a 
smaller and simpler board, so 12V/2A may be enough. Anyway, design task 
for final PCB designer should include this item:
  - Give an estimate of total power consumption. How much current @ 12V 
will the board require?

2. EIM Interface

Turns out, we will not be able to have separate address and 32-bit data 
bus. The higher part of data bus (signals EIM_D[16]..EIM_D[31]) are 
multiplexed with SPI and UART modules in iMX6Q. We can either have SPI 
and UART, or 32-bit EIM. In this situation I suggest using separate 
24-bit address bus and 16-bit address bus. At 66 MHz this will give us 4 
times more bandwidth, than we have now.

3. USB-to-Serial Converter

I'm afraid, MAX3421E is not what we need. It is not a transceiver, it is 
a Peripheral/Host controller. It does have SPI interface, but this 
interface is used to communicate with its internal registers, not to 
communicate with external system. I believe, what we actually need is 
FT232R from FTDI or maybe CP2104 from SiLabs.

--
With best regards,
Pavel Shatov