Re: 18F452 to SL811HS interfacing

Tristan Mumford wrote:
Donald wrote:


Tristan Mumford wrote:

Hello.
I've been trying with limited success to interface a 18F452 uC to a
SL811HS USB host/slave IC.

I've pretty much debugged the software, but have hit a nasty brick wall
in hardware. I seem to be reading garbage from the IC. Ie no matter what
address I look at it's the same value. The really bothersome thing is the
omnipresent value changes every so often.

Is there anything I need in between these two chips? I'm using port D for
the databus and some of port C for the read, write and A0 lines.

The interface between the two is direct. Ie nothing in between. Should I
have something like a '245 or a network of pullups or something like
that?

Please post a schematic.


http://g.fondeville.free.fr/usb_en.html


So, you removed the '245 from your circuit ???


Let's just say that is it. After the original post I received an e-mail
alerting me to the project. It was nearly identical to mine, so I
rearranged a few IO lines to make it compatible (except the uC on mine runs
at 8MHz). Then I changed a few "#define"s in my source to match.
Amazingly enough my alterations didn't change anything for better or worse.

Going from a feeling, it's like either D0 is stuck high, or the nWR line
isn't working. I can't find a sign of either being the case though.

Given that the value it regurgitates isn't changed even if I write a value
to an address and read it back immediately the problem is a little hard to
pin down.
.

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