[time-nuts] Low cost logic analyzer

Bob Paddock bob.paddock at gmail.com
Fri Apr 25 20:47:51 EDT 2008

On Friday 25 April 2008 11:49:28 am Ulrich Bangert wrote:

> However, these days I had VERY strange problems
> with an I2C bus based device.

Build yourself one of these to show you what is going on,
on the I2C lines; won't get any lower cost than this (about $3):



Adding Windows NT/2000/XP Support to the AN3315 Parallel-Port 2-Wire Software

Abstract: This application note is a supplement to two previous application 
notes, which effectively extend the usage of the parallel-port, 2-wire 
hardware (presented in AN3230) and software (presented in AN3315) to 
computers operating on Windows® NT/2000/XP platforms.

> Communication on the bus would work flawlessly over hours and then stop
> due to... yes, due to what?

I2C devices are so notorious for locking up that Linear Technology makes a 
device to unlock them, read up on how it works, then do the same in your 

"LTC4308 - Low Voltage, Level Shifting Hot Swappable 2-Wire Bus Buffer with 
Stuck Bus Recovery"



Also look at the LT1694 and LTC4311:

I try to avoid I2C devices in any of my designs if at all possible.
May I2C parts simply are not implemented correctly.

If you really want to get hosed over try dealing with some of the newer
accelerometers that put I2C and SPI on the same pins, with High for I2C and
low for I2C on the single "chip select" line.  Doesn't work if you want to use 
SPI reliably...

 http://www.softwaresafety.net/ http://www.designer-iii.com/

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