[Tinyos-devel] Tinyos 2.0 - MSP430 Spi Wiring

[Max CORTIANA]

Hi all

I've seen the TinyOs 2.0 SPI modules for MSP430 and I've a question 
about a wiring in the Msp430SpiNoDma0P module.

The generic module Msp430SpiNoDmaP() provides these interfaces:

  interface HplMsp430Usart as Usart
  interface HplMsp430UsartInterrupts as UsartInterrupts
  interface Resource as UsartResource[uint8_t]

UsartInterrupts and UsartResource are provided interfaces and they are 
then connected to HplMsp430Usart0C by Msp430Spi0C.
Instead Msp430SpiNoDma0P directly wires Msp430SpiNoDmaP.Usart to 
HplMsp430Usart0C.HplMsp430Usart.

My question is: Why the module is directly connecting to USART0 Hardware 
Presentation Layer?
I supposed it would have been connected to Msp430Usart0C.HplMsp430Usart.

If i see well, at the end that's the same thing, but Msp430Usart0C is 
the Component providing interfaces which dial with the shared hardware 
module USART0 and upper layers should connect to it.

Hope the explanation is clear enough, a graph would be more immediate!

- Max