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• TI Thinks Resolved

# LDC1101EVM: Use LDC1101 count coin

Part Number: LDC1101EVM

Dear Sir,

We use LDC1101 EVM to count coin.

We continuous roll 30 pcs coin, but always have 2 less.

Do you have idea? the attached file for your reference.LDC1101 EVM Test.docx

• Hello,
from the spreadsheet which you attached, it seems that the LDC1101 is sampling correctly, and you are making sure that you have a sufficient amount of samples per coin. I expect that your counting algorithm doesn't process the data properly. For example, around sample 2200, there are two dips in the output code in rapid succession. Is it possible that this was caused by two coins being in the chute at the same time (one coin 'pushing' the other one through the chute). This would be seen by a sensor as a partial dip because the sensor 'sees' some of the metal from each coin as they move through the chute together, and RP does not return to 42000. It is important for your algorithm to capture such an event. I recommend implementing the algorithm in such a way that a coin is detected based on the rate of change of the RP that it produces, rather than using an absolute threshold.
Best regards,
Applications Engineer
Silicon Valley Analog Group
Texas Instruments

Dear Sir,

Could you help us to check the attached file?

Thanks!LDC1101 RP curve.docx

• In reply to Vincent Hsieh:

Hi Vincent,

Are you continuously sampling the LDC1101? Can you get a scope shot of the INA pin to ground showing ~30 cycles of the sensor oscillation?

ChrisO
• In reply to Chris Oberhauser:

Dear Sir,

If we use L, the number is correct, but can not distinguish between true and false

Only be used R to distinguish between true and false, the coin is 30ms through the 10mm sensor, If we put coins is slowly,not continuously , the numebr also is correct by R.
Have requirement on the speed of the coin?

How to read the L and R at the same time in EVM?
• In reply to Vincent Hsieh:

Hello Vincent,

The LDC1101EVM GUI does report RP+L or the LHR data, but not both simultanesously. The LDC1101 does convert all 3 measurements simultaneously. Unfortunately, the USB interface used with the LDC1101EVM is USB1.1, which does not provide enough useful BW to transfer the LDC1101 output data when the LDC1101 is configured for higher sample rates. This results in some artifacts with the EVM which are not from the LDC1101.

Regards,

ChrisO
• In reply to Chris Oberhauser:

Dear Sir,

Thanks, so we how to do to get the RP+L from LDC1101
• In reply to Vincent Hsieh:

Hello,
To read RP+L data using the GUI, please refer to page 17 of the LDC1101EVM user's guide: www.ti.com/.../snou137.pdf
Regards,
Luke