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Can't get SDO data out of a LTC2402
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RawCode:
Hello guys.
I'm quite demoralized.
I'm trying to build something like a source-meter for my thesis work. Everything seems to work, except for the LTC2402. Seriously, it's driving me crazy.
I tied the LTC2402 to a Nucleo-F767ZI according to these schematics:
i.e. CS to PE6, SCK to PG11 and SDO to PA6. I also setted the SPI configuration as follows:
So, according to the LTC2402's datasheet, when CS goes low, SDO goes low too if the conversion is finished, otherwise it stays high. When CS goes high, SDO goes to Hi-Z.
But, anything i do, i can't pull data from the LTC2402. SDO seems to stay in an unknown Hi-Z state, even if CS is low.
I tried to pull-down SDO and SCK to DGND, but nothing changed.
Here the signals at the oscilloscope. CH1 and CH2 represents SDO and SCK. I inverted CH1 and CH2 in a picture. Sometimes i get a "smaller" replica of SCK signal on SDO, sometimes something that seems a GND on SDO, sometimes a very noisy replica of SCK signal on SDO. I handsoldered it to a pcb, so maybe the solder job is not the best, but there is continuity in all signals, even touching the package leads.
Please, can you help me?
exe:
I'd clean flux, just in case. Also, may be the part is damaged...
Giaime:
After a quick look, I'd suggest you pull-up SDO instead of pulling it down. Try 10k resistor and let us know.
SiliconWizard:
Couple thoughts:
- You need to pull SDO to something, because it's in Hi-Z when /CS is high. Leaving it floating is not a good idea. The datasheet suggests pulling it low. You said you tried and it didn't make a difference. I can't believe it didn't. At least when /CS is high, instead of seeing a signal in a typical "hi-z" state, you should see a straight low level. If not, something else is clearly wrong. Maybe your soldering.
- How do you control /CS? Did you take a look at it? Would be interesting to look at it with the scope. Maybe it's actually not controlled properly. This point might be due to an improper software configuration.
RawCode:
Hello guys, thanks for all your replies.
After trying everything, i changed the ic and now it works.
My father checked the board in the microscope before changing the ic and he says it was well soldered. So I presume it was kinda faulty.
Luckly enough i had a spare of this ADC.
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