Implementing USB master mode in Firmware
Posted on 2003-10-28
This is a somewhat hack-ish question but maybe this is the right place.
First off, is a limited scope but fully firmware USB Host / Master feasable?
By limited scope, I mean that this Host will only be able to recognise / interact with specific USB devices and endpoints. eg. Only USB memory sticks.
The application in mind is requiring offline / removable storage and the USB memory stick is the ideal candidate but the cost of a full USB Host controller IC is prohibitive in respect of the cost of the application requiring it.
Or rather, I ask the EE forum, where could one look to find some low level USB protocol and data frame specifications so that a USB host can be created that speaks to USB memory sticks only?
The processor in mind is a small-ish PIC 18F.
PIC18F252 with pretty much all the serial port hardware / timers that should be necessary. At about 20+ MHz, I feel this should be enough to handle the protocol parsing and processing load.
Other MCU suggestions are welcome within reason of course...
but cost is the limiting factor otherwise a commercial USB host would have been used...
ps: The project is a media playing device using USB memory devices.
pps: It's not for a commercial application, just a "hobby" one.