[NTLK] MP2x00 Internal Interconnect Breakout

Matthias Melcher mm at matthiasm.com
Tue Jan 13 19:06:58 EST 2015

> On Jan 14, 2015, at 12:21 AM, Jake Bordens <jake at allaboutjake.com> wrote:
>> - fixing the timing bug that requires slowdown.exe on MSWindows
> Interested to know more about this, since you've mentioned it before.

The MP and PC exchange data in blocks, using checksums and ACK/NACK to re-request blocks with checksum errors. To make this as fast as possible, the communication overlaps, meaning, the PC can send the next block even before it receives the ACK for the previous block. If a NACK is received later, that NACK contains the number of the block that must be resent.

It seem that the MP is busy verifying the checksum before it reopens the serial port for receiving again. A fest PC has already started to send the next block, now causing framing errors and failed checksums all over the place.

If I add a little pause between blocks, I hope to slow down the connection just enough, without slowing down the PC - it just makes the USB buffer available a little bit later.

> guess I'm a Mac user and don't experience this?

Since the original tools no longer work on OS X, this problem has not crept up. I assum the current OS X tools are reliable. In either case, the delay would not be a disadvantage, since it only synchronizes actions.

>> And finally for the crazy part. We have access to the otherwise unused 
>> serial port 3, so why not use it and add some functionality?
> One crazy idea I had was to control a Si5351 clock generator and make an 
> overclocking "implant" that could be switched by serial command.

Ooooh, nice idea. I like it!

> I'm still partial to the WiReach module. 
> (http://www.connectone.com/?page_id=3527) --especially if we could do 
> external clocking and ~2mbit speeds. An all-in-one dream of an internal 
> wifi card with USB would be damn sweet.  The chip would be able to select 
> for USB or WiFi-PPP.  I think the big constraint in this case is physical 
> space inside the case.

Yep, now we are hitting space issue. I was thinking about a GSM card. Imagine using the MP to do a phone call... . 

More information about the NewtonTalk mailing list