[time-nuts] Low cost logic analyzer
Bob Paddock
bob.paddock at gmail.com
Sat Apr 26 00:47:51 UTC 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):
http://www.maxim-ic.com/appnotes.cfm/an_pk/3317
http://www.maxim-ic.com/appnotes.cfm/an_pk/3230
http://www.maxim-ic.com/appnotes.cfm/an_pk/3315
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
driver:
"LTC4308 - Low Voltage, Level Shifting Hot Swappable 2-Wire Bus Buffer with
Stuck Bus Recovery"
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1007,C1070,P39466
LTC4309:
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1007,C1070,P39073
Also look at the LT1694 and LTC4311:
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1007,C1070,P1710
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1007,C1070,P60184
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.wearablesmartsensors.com/
http://www.softwaresafety.net/ http://www.designer-iii.com/
http://www.unusualresearch.com/
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