[minima] Re: Yet more on Wire.h / I2C FET Interface...
- From: Mark <mark.g0mgx@xxxxxxxxx>
- To: "minima@xxxxxxxxxxxxx" <minima@xxxxxxxxxxxxx>
- Date: Sat, 1 Feb 2014 06:53:43 +0000
That's a shame as it looked so simple.
What devices are used in the design on the link you sent?
-----Original Message-----
From: "Michael Yancey" <mikeyancey@xxxxxxxxx>
Sent: 01/02/2014 00:57
To: "minima@xxxxxxxxxxxxx" <minima@xxxxxxxxxxxxx>
Subject: [minima] Yet more on Wire.h / I2C FET Interface...
OK - I hereby retract my statement, temporarily.
Currently, I'm having TERRIBLE luck with the BS170s (and pullups to
3.3V S side and 5.0V D side). I2C ...sorta... worked. Occasionally.
If the wind didn't blow. From the northwest.
Had intermittent troubles with I2C READs not returning proper data,
I2C just failing.
So, I've gone back to: twi.c / commenting out the pullups, plus adding
a 3.3V pullup at the Si570. Works... EVERY TIME.
I may try this again, but with different FETs. BS170 just can't seem to
keep up with the speed. Writes work ok / Reads either come up short
(4 or 5 out of 6 bytes) or read 0xFF instead of the real register.
Perhaps a BS138 or an 2N7000 (same as BS170).
I'll keep experimenting.
For now, apologies if I've caused any loss of time (heh, I sure have wasted
about 4 hours of mine!!)
--
..
Mike Yancey
Dallas, Texas
http://www.mikeyancey.com
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