hi Jtw11 :
thanks for your reply ... i wasn't checking on a regular basis and therefore the delay.
i would possibly have a few questions regarding the CJ125 and LSU4.x
i used my arduino as an ISP and it also powered the target board with atmega328p-au.
however i did not power the cj with 12V, but with 5 V only from the ISP during the initial download and other non cj related firmware tasks.
then i discovered that a bosch spec says that
Vub < Vcc ... during power up 100 ms max ... accumulated over lifetime 2 h max.
i did so violate the specs for Vub not being less than Vcc.
i did a correct setup of the cj i believe and observed the following on pin UN.
cold sensor about 3.5 kHz square wave with rc flanks, which is correct. this is the wave form from pin CM forcing the Ri measurement current through the cold nernst cell.
but when i slowly cranked up the heater ... slowly with a variable power supply i saw the amplitude slowly getting smaller as the Ri nernst got smaller and then it got very distorted right near the t7 nernst cell open short measurement timing ... hard to describe ...
also as i was performing a test with a regular pot instead of the nernst cell, the 3.5 kHz amplitude got smaller as i lowered the Ri simulation, with no distortion.
the distortion came from the pump cell therefore.
i tested the sensor on a known good cj125 design where i purchased the board and it worked fine, so the sensor seems ok.
i assume that the cj125 is somehow damaged ... it's hard to follow all the details of the cj125 and it's internal timings, even being somehow explained.
i abandoned the atmega and redesigned the board with an arm lpc1347 ... ported the firmware and have a smooth sailing so far ... only on the arm eval board so far ... expect the 1st 2 boards from pcbexpress, now sunstone circuits, next week.
got a soic-24 cj125 now instead of the lqfp-32 which is a nightmare to probe the pins or to replace to begin with.
what were your experiences so far ... i would be very very interested to hear
thanks for your reply so far and cheers, blue2u
p.s. if you want to handle this topic for whatever reason "off this forum" to not get the arduino community bored, it's fine with me too ... i would prefer the forum ... maybe others are interested as well.
anyway you can also email me at efiHacks@gmail.com