Test protocol
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lvcards: 3,4,5,6,7,8,9:
20260615_160912.jpg

lvcards: 9,10,11,12,13
20260615_160920.jpg

Measurements
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Lennart soldered wires on SCL, SD.
We looked at oscilloscope on SCL:blue, SD:yellow

lvcard #12 : is OK
20260625_150245.jpg SCL,SD when reading mcmtemperature
20260625_150317.jpg lvcard12

lvcard #4: I2C to MCM not working after first power off/on of MCM
20260625_151318.jpg  SCL,SD when reading mcmtemperature - start (50usec scale)
20260625_151615.jpg  no activity, mcm powered on
20260625_151646.jpg  no activity, mcm powered off
20260625_152843.jpg  SCL,SD when reading mcmtemperature (10usec scale)
20260625_153026.jpg  SCL,SD when reading mcmtemperature - end (50usec scale)
20260625_153824.jpg  SCL,SD when power off MCM (20 ms scale)
20260625_154004.jpg  SCK,SD when power on MCM (20 ms scale)
20260625_154153.jpg  lvcard4

lvcard #12 : is OK
20260625_154700.jpg  SCK,SD when power on MCM (20 ms scale)
20260625_154812.jpg  SCL,SD when power off MCM (20 ms scale)
20260625_154947.jpg  SCL,SD when power off MCM (500 ms scale)
20260625_155152.jpg  lvcard12


lvcard #13: I2C to MCM not working after first power off/on of MCM
20260625_160646.jpg  SCL,SD when power off MCM (20 ms scale)
20260625_161051.jpg  SCL,SD when reading mcmtemperature - start (20usec scale)
20260625_161310.jpg  lvcard13

accessing (reading temperature) MCM I2C after poweroff/on of MCM
shows no signal on SCL/SD. It stays "high".

Two ways to reset:
1. cycle power to lvcard
2. let the processor reset itself by a watchdog timeout.

after any of these the I2C works once before power off/on of MCM.

Next step
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Modified lvcard processor program to:
1. show I2C status registers
2. force I2C to idle state
3. force reset of I2C on processor
4. more error checking in mcm temperature reading routine

tests done with no SRU clock (SRU used by DAQ).
bus state must be idle for I2C access to work.

lvcard13:
---------
When poweroff mcm the I2C bus state goes from idle to busy.
when power on it stays busy.
2 and 3 above sets bus state to idle

lvcard 12:
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behave today the same as lvcard13
before it was OK.

lvcard 11:
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still working but:
when poweroff MCM bus state goes to busy
when poweron MCM bus state goes to buserror and idle.
after first I2C access buserror is cleared and state is idle.

Possible software fix:
after poweron/off check bus state and clear buserror and set state to idle.