HTRC110 noise on transparent mode

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HTRC110 noise on transparent mode

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alasa995
Contributor II

Hello,

I am using HTRC110 to read some LF transponders and I had this issue of noise on DOUT once I send READ_TAG command. So, I send this sequence of configuration commands:

 

SET_CONFIG_PAGE(0x72); // CONFIG_PAGE 03, clock frequency = 8 MHz, smart_comp = On, low pass = On
SET_CONFIG_PAGE(0x43); // CONFIG_PAGE 00, fL = 6KHz, fH = 160 Hz, gain0 = 16, gain1 = 31.5
SET_CONFIG_PAGE(0x50); // CONFIG_PAGE 01, coil driver active, hysteresis off, device active, idle mode
SET_CONFIG_PAGE(0x60); // CONFIG_PAGE 02, threst = 0, acqamp = 0, freeze = 00[normal operation]
ms_delay(10); // 10ms delay
smp_t = GET_PHASE(); // sends 0x08 to HTRC and read phase
smp_t << = 1;
smp_t += 0x3F; // Fixed offset compensation value
smp_t &= 0x3F;
SET_SAMPLING_TIME(0x80 | smp_t); // Send sampling time
ms_delay(10); // 10ms delay
SET_TRANSPARENT_MODE(0x03); // Send 0x03 to HTRC

 

I check for every page written with GET_CONFIG_PAGE and I get the values I set to the HTRC correctly. Also, for the antenna check, I get ANTFAIL = 0. But once I set the transparent mode I get this garbage on the DOUT pin:

cap1.png

Although I can see a meaningful output when I put a token near my antenna, that persistent garbage doesn't allow me to properly decode the signal. I need to mention that turning the hysteresis OFF and changing few parameters slightly give less noticeable garbage, but still that doesn't allow me to decode the signal properly. I am using a custom board for this LF decoding, the HTRC shares power rails with the MCU and has an 8MHz oscillator, I checked the noise on the power rails and probed the RX pin on the HTRC and all seemed good. Did anyone have this same issue with the HTRC?

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Fabian_R
NXP TechSupport
NXP TechSupport

Hello sir,

This is Fabian from customer support, thank you very much for using our products.

It is possible that this signal occurs due to the requirement of a calibration of the decoder. Could you please clarify if you are using our HTRC library? We do have a User Manual that explains the procedure for calibration but,

it is required to sign an NDA to gain access to the mentioned documents. If you need further support on how to get an NDA please take a look at this document and FAQ:  https://www.nxp.com/support/support/non-disclosure-agreement-faqs:NDA-FAQS

To request access after getting an NDA:

https://www.nxp.com/docs/en/user-guide/nxp-secure-files-user-guide.pdf

 

Once followed the above user guide, please request access to UM9810.

Best Regards,
Fabian
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