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P82B715
#11

Sorry for digging out this thread again, but I wanted to know if anybody else also had trouble in using the bus extension ICs.
Always when the IC is in the socked it destroys the whole I²C bus and pulls it to a strange voltage level at about 2.5V.
I had the problem now with two TX boards and two different ICs.

So there are two possibilities:
- I'm doing something very wrong
- It accidently bought some counterfeits which are not working.

Maybe someone has an idea what could be happening here.

Regards,
engolling
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#12

Hi engolling,

I'm using those chips in all my TX boards, some with Philips brand others with NPX brand (from China), never noted any problem with the I²C bus.
Check if R7 and R8 are installed (both 4.7K)

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#13

Hello Werk,

I think I installed everything correctly, but I will check twice.
I was just wondering because I had the issue with two TX boards.

engolling
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#14

(28-04-2018, 17:00)engolling Wrote:  Hello Werk,

I think I installed everything correctly, but I will check twice.
I was just wondering because I had the issue with two TX boards.

engolling

Indeed that is strange.
I just can asure you that there are a lot of people (majority I think) using temperature / humidity sensors connected to the I²C bus of the P82B715, as I do too.
Those who are using the Soil/Leaf interface also have it connected to the P82B715 I²C bus, which presupposes that the "primary" I²C is working normally.



(24-04-2018, 22:03)engolling Wrote:  Know issues:
  • Since the ordering hand was faster than the brain there is a routing error on the PCB. Instead of A4 and A5 the pins D4 and D5 are routed to the I²C connector to the TX module. Therefore some extra wires have to be soldered to the PCB. More explanation will follow soon.


Out of curiosity,  do you have tested it with a regular I²C sensor or with your height of snow interface? Due to the error on the board, is there any chance that D4 and D5 are become in parallel with A4 and A5?

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#15

Hello,

today I managed it to test the ICs again.

It seems that the ICs I got simply do not work. I will get some new ones and test them again.

Quote:Out of curiosity,  do you have tested it with a regular I²C sensor or with your height of snow interface? Due to the error on the board, is there any chance that D4 and D5 are become in parallel with A4 and A5?
I tested both, a regular sensor and my emulated sensor and none works.


In fact the presence of the "bad" ICs prevent the TX module from booting. I think it can't even initialize the I²C bus and freezes at some point.

Regards,
engolling
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#16

Hi,

If you want, I can send you (in the same package of the Wireless Display units) one of mine P82B715 chips. Say something until tomorrow morning.

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#17

Hello,

the IC I got from Werk is working fine (thank you very much Smile ). So it seems that it is possible to get some defective counterfeit ICs.

In summing up - one cause for a not correctly booting TX module could be a bad P82B715 I2C extension IC.
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#18

Hi,

Thanks for the update.
Never before I has heard of any problem related to the use of these chips. Most chips I prefer to buy from sellers like RS Online, Mauser etc. Price for quantities of 20 to 50 units are almost the same than in China, the only problem is the shipping costs, however most of these sellers offer free shipping for purchases above a value ($50 USD), so its just a matter of combining several orders at the same time.

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