ZX device as a USB host

[Don_Kirby]

A project was recently proposed which requires a microcontroller to function as a USB host to a piece of video equipment. The USB command structure is well documented and poses little difficulty in regards to programming. Are there any devices in the current lineup that offer this functionality?

-DK

[dkinzer]

Are there any devices in the current lineup that offer this functionality?

There are no ZX devices that offer USB functionality. The only AVR chips that provide USB host capability are the AT90USB647 and AT90USB1287 and then only the reduced-function OTG Host capability. There is no direct support in the ZBasic Library for USB functions. The LUFA USB stack may be useful in this regard.

[stevech]

Not much RAM, but couldn't ZBasic native target the ATMEGA32U4? You'd have to find/integrate a USB driver.

[dkinzer]

[C]couldn't ZBasic native target the ATMEGA32U4? You'd have to find/integrate a USB driver.

I believe that all of the mega AVRs with USB are client only except for the two that I mentioned. I make this distinction because the OP seemed to be asking about USB host capabilities.

It may be that the XMEGA USB devices support host mode but it appears that the LUFA stack for XMEGA does not.

[Don_Kirby]

The LUFA stack documentation does makes some mention of host management. My limited knowledge of USB would be the limiting factor in this method of implementation though, even if the stack were capable of functioning as a full USB host. 'Biting off more than you can chew' would the appropriate idiom I would think.

[dlh]

There is a limited open source implementation of a low speed USB Host using a Mega32 at...
https://instruct1.cit.cornell.edu/cours ... index.html

From the above link...

This project has yielded a library that can be included from any program written for the Mega32. By using this library, a user can implement USB functionality with their application with minimal fuss. Several compiler options are included for various levels of debugging and verbosity.

The Mega32 is supported under the Generic License. I've no clue as to how doable this may be with ZBasic.

[dlh]

I spent some time researching this a year or two back but I've had to set most of my projects aside due to health issues. Maybe some of the links I found will be helpful to you or others.

If the Mega32 project I posted about earlier does not meet your needs, the MAX3421E can be either host or peripheral and it does both low and high speed USB.

There was an article on the MAX3421E in Circuit Cellar Issue# 202 (May 2007). You can download a PDF copy of the issue for $6 from...
http://www.cc-webshop.com/Circuit-Cella ... 07-202.htm

Circuits@Home sells an Arduino USB Host shield (asssembled or bare board) using the MAX3421E and there is extensive documentation at...
http://www.circuitsathome.com/mcu/light ... hostpart-1

I also found a PIC based USB Host to Serial TTL module on EBay but I cannot find the link now. If I come up with it, I'll post a link later. It used a PIC24xxx and was not very well documented. There is extensive PIC24 documentation on Microchip's web site.

I found the missing link to the PIC24 based USB Host device...
http://www.sureelectronics.net/goods.php?id=1140