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Can a USB host be implemented using an 8 bit uC?

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klpang1

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usb 8-bit cpu

Hi all,

I am thinking of implementing an USB host on a data logging device and are looking at various method of doing it. My final intention is to attach a pen drive ( which are cheaply and readily available ) to the data logging device and remove it after a month and copy whatever data stored in the pen drive to a pc.

From information gathered on the net, it seems that most USB host are implemented on higher end micro processor. I intend to build the USB 1.1 host that will only access pen drive. I understand that i also have to write the interface for the FAT32. Any suggestions or ideas or valuable links?

Thanks.

chicken_feet
 

avr-based usb host

Cypress microprocessor is a 16 bit device
 

cypress usb host fat32

Hi,

I have seen a post in this forum which used a Atmel AVR to implement the whole USB protocol. You can try to search in this forum.

BR
Keith
 

usb host 8bit

ee_wmkab said:
Hi,

I have seen a post in this forum which used a Atmel AVR to implement the whole USB protocol. You can try to search in this forum.

BR
Keith
Click to expand...
You referring to the IgorPlug? That's a usb device, not a host, but still quite an impressive achievement nevertheless.
A host is much more complicated than the device. But since IgorPlug has managed to generate usb signals, and if you are VERY VERY familiar with the USB specs, I reckon it could be achievable for a simple host with no power/bandwidth control, no multi-device interface etc etc.
In short, it is extremely difficult but not impossible.
 

Check this: **broken link removed**

AT43USB370 has integrated USB host and it is 8-bit uC (AVR-based).
 

I have done an extensive search through google and couldn't find a USB host implemented using an ordinary 8-bit uC. The Atmel's USB host i think is not AVR-based. The USB devices are AVRs, but not the host. CMIIW.

I am considering to use an embedded PC to interface USB devices, because i noticed that USB host chips are intended to be interfaced with high-end microprocessors or microcontrollers (CMIIW). Hence it would be very difficult for me to build such a system (USB-host) by myself.
 

The Cypress SL811HS is an 8-bit peripheral, and can be used as a USB host. The Atmel USB hosts are also peripherals.
 

am thinking of implementing an USB host on a data logging device and are looking at various method of doing it. My final intention is to attach a pen drive ( which are cheaply and readily available ) to the data logging device and remove it after a month and copy whatever data stored in the pen drive to a pc.
Click to expand...

Why didn't use MMC, SD or compact card? to implement the file system stack is not an easely task... and in your project is doubled by the USB host code...

hope this help,
//a
 

hi //a!
may be chicken_feet is planning to download the logged data on to PC. If he goes for MMC or SD card instead of USB Pen Drive, he has to spend some more money on MMC/SD card reader.

-vasu
 

On the other hand, you may want to take a look at USB On-The-Go (OTG) chips with pseudo-host functionality.
 

vasureddym said:
hi //a!
may be chicken_feet is planning to download the logged data on to PC. If he goes for MMC or SD card instead of USB Pen Drive, he has to spend some more money on MMC/SD card reader.

-vasu
Click to expand...


that's my main intention. Base on the current price of pen drive, i believe it would continue to drop. so far the price of a 128Mb of pen drive over here cost around USD15. Anyway, i am still searching around for the best method to acheive my aim, it may not be pen drive after all.

While strolling at a super market recently ( the favourite pastime ), i came across a digital camcorder with a hardisk of 4G! and the size of that storage is like a compact flash! I still don't know if that is a CF or a miniature HD, will find out later.
 

I have been involved in implementing USB host stack and I would not recomende that if you can awoid it. Lots of hard work and much standard documents reading.

I was doing it in a 32 bit embedded enviroment with PCI, a bit diferent from 8bit but I think the stuff that needs to be implemented is something simular, and I just dont think its possible with just 8bits.

One part of it is also the memore requrements of the stack, if there is only an 8bit CPU I would guess that there would not be enouge memmory.

If you have been working with the device side I would guess that its about 10-20 times that amount of work needed to get something running at all...

re Me
 

Thank you for your infor. I have not done much reading on this and i appreciate your sharing.

rgds,
chicken_feet
 

chicken_feet, Has you studied the host spec for OHCI or UHCI ? If not, I suggest that you should study it first in order to know the tasks that host should do. After that, I think you may know the real problem for 8 bit mcu to implement functions of host mode.
 

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