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From: Andrew Jackson on 20 Dec 2008 04:13
>> If you are short of pins you can use just MISO on the MAX3421E. To make
>
>> life easy I would initially try and use one pin for one function: it
>> makes the system less complex that way and hence easier to get working.
>
> Our adviser suggested to use this interrupt-on-change pin from the PIC..
> Pins 25-28. Can we actually supplement this either this pins for GPX??

If you draw up a list of what pins your are going to use on the PIC and
the MAX3421 that would be helpful. Use the function not the pin number
(e.g. PB6, etc.) rather than the pin number (unless you specify package
types).

Andrew
From: urefowei on 20 Dec 2008 07:31
if anyone can help us.. please feel free to yahoo messenger or mail at
urefowei(a)yahoo.com

thanks
From: urefowei on 20 Dec 2008 07:43
if anyone can help us.. please feel free to yahoo messenger or mail at
urefowei(a)yahoo.com

thanks
From: urefowei on 20 Dec 2008 07:57
We already did list our required functions as of Figure 21 (MAX3421E in a
Host Application) of MAX3421E DS..


is this diagram enough??

or do we need to add additional peripheral features to accomplish
this.....
>we are doing a thesis on a flash to flash bridge
> This project aims to develop microcontroller-based device that can
handle
> data transfer from a USB storage-device directly to another USB
> storage-device. The previous project's device transferring
capabilities
> were limited in terms of data size, file types, and transfer rate.

if you are a bit confused of our objectives, we are doing a device similar
to
this product
http://shopping.yahoo.com/p:Delkin%20Devices%20DDUSB-BRIDGE%20USB%20data%20copier:1991465603

thanks
From: Joe Chisolm on 20 Dec 2008 13:39
On Wed, 17 Dec 2008 05:34:41 -0600, urefowei wrote:

> we are doing a thesis on a flash to flash bridge This project aims to
> develop microcontroller-based device that can handle data transfer from a
> USB storage-device directly to another USB storage-device. The previous
> project's device transferring capabilities were limited in terms of data
> size, file types, and transfer rate.
>
> we are currently using PIC184550 as our MCU and the MAX3421E as the host
> controller..
>
> Looking at Figure 21 (MAX3421E in a Host Application) of MAX3421E DS (page
> 26),we could not connect SS and GPX, SPI serial slave output and interrupt
> pin, respectively, to our PIC..
>
> What can we do about this??
> Can we supplement other IO pins on our PIC for these purpose??

I think you are making this more complicated than it needs to be.
I'm not sure why you are having a pin count problem, the 18F4550
has a boat load of pins.

You dont need an interrupt for the 3421 GPX pin unless you
configure it for INT or SOF output - which you probably dont need in
this app. There is no reason to make GPX the interrupt pin -
UNLESS you are trying to do something with the other GPIO pins and
need interrupt status on them. In either case just tie the INT or
GPX pin to a PIC INTx pin and configure the PIC for rising or falling
edge as needed. All the other GPX functions are just operational
status. Tie the GPX to a PIC (configured) input pin and monitor the
pin in your firmware loop.

You do not need to use an external transceiver for the PIC device
USB side. Use the internal transceiver and either the internal
voltage regulator or the 3.3V you supply to the MAX. If you use
the internal regulator remember to tie VSUB to ground with a 220nF
cap. The PIC USB core has it's own set of interrupts. Your ISR
can easily determine which USB side is knocking on the door.

The 4550 has a MSSP that will do SPI - see section 19 of the
18F4550 data sheet. Configure the MAX for full duplex mode.
MasterInputSlaveOutput (MISO) pin goes to the PIC SDI pin.
Tie the 4550 /SS pin to the 3421 /SS pin. Are you trying to
use more than 1 SPI slave device, eeprom or something else?

You can use the same 12Mhz clock source for the MAX and the
PIC. Use the PIC PLL block with a divide by 3. If you have
a 18LF and NOT using VDD=5V watch your core clock speed.
See the chart back in the electrical spec section.


--
Joe Chisolm
Marble Falls, TX

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