CLRC663 Plus LPCD with Filter option enable

[InakiNagore]

Hi,

I'm having some trouble when I implement the filter option for the LPCD. I set the LPCD_FILTER bit to 1 "LPCD_Options register (address 3Ah)" but It seems not to be working well. It interrupts after the RF on pulse without presenting a card. 

I've increased the RF on time because the CLRC samples 16 times during the RF on time instead of sampling just once. I've tried with 200us of RFon time but it continues interrupting when the RFon time finish. The value of LPCD_Result_Q and LPCD_Result_I is 0x00h when we get the interrupt.

I suppose there must be something that I'm configuring in an incorrect way. Is there any documentation of LPCD with filter option and what times should be used for this configuration?

Thank You,

Iñaki

[estephania_mart]

Hello,

Are you using the development kit and the NFC reader Library ?

Have you tried configuring the register with the Cockpit Tool ?

If you are interested in the LPCD functionality, could you please help me check this application note?

Regards,
Estephania

[InakiNagore]

Hello Estephania,

I'm using a custom board with the CLRC663, not the Dev Kit.
I've made a library, I'm not using the NFC reader library.

We can let the CLRC663 working properly in LPCD mode with or without Charge Pump easily and Filter disabled, but when we set the Filter Bit to 1 it doesn't work. Theoretically that should be the only change we should do to add the filter option.

Related with the App Note: 
- 3.2 LPCD_FILTER tells that it samples 16 times during the RF on time. This algorithm increases the RF on time by the factor of two or three in case of instability.
- 3.7 LPCD features (CLRC663 plus only) tells that samples 64 times at the cost of a longer RF on time.
- 3.6 The LPCD detection: 3 µs ≤ tRFon ≤ 10 µs -> operation with TVDD = 5V, Charge pump enabled &
LPCD_FILTER enabled

So theoretically with a RFon time of 10us should be enough. We don't need to care about the RFon time, isn't it?

I add a picture where we've configured a RFon Time of 60us, the IRQ is configured only to change with a LPCDIrq. When we read the LPCD_Result_Q and I registers, the result value is 0x00.

Regards,
Iñaki

[estephania_mart]

Hello,

If you are using your own library , could you please make sure that you are following all the necessary steps to write to the EEPROM ? You can find an example of this in this application note, Using the RC663 without library if it is not working it might not be set correctly, could you please help me check it and confirm ?

Regards,

Estephania

[InakiNagore]

Hello Estephania,

I'm using a custom board with the CLRC663, not the Dev Kit.
I've made a library, I'm not using the NFC reader library.

We can let the CLRC663 working properly in LPCD mode with or without Charge Pump easily and Filter disabled, but when we set the Filter Bit to 1 it doesn't work. Theoretically that should be the only change we should do to add the filter option.

Related with the App Note: 
- 3.2 LPCD_FILTER tells that it samples 16 times during the RF on time. This algorithm increases the RF on time by the factor of two or three in case of instability.
- 3.7 LPCD features (CLRC663 plus only) tells that samples 64 times at the cost of a longer RF on time.
- 3.6 The LPCD detection: 3 µs ≤ tRFon ≤ 10 µs -> operation with TVDD = 5V, Charge pump enabled &
LPCD_FILTER enabled

So theoretically with a RFon time of 10us should be enough. We don't need to care about the RFon time, isn't it?

I add a picture where we've configured a RFon Time of 60us, the IRQ is configured only to change with a LPCDIrq. When we read the LPCD_Result_Q and I registers, the result value is 0x00.

Regards,
Iñaki

[InakiNagore]

Hello Estephania,

I'm using a custom board with the CLRC663, not the Dev Kit.
I've made a library, I'm not using the NFC reader library.

We can let the CLRC663 working properly in LPCD mode with or without Charge Pump easily and Filter disabled, but when we set the Filter Bit to 1 it doesn't work. Theoretically that should be the only change we should do to add the filter option.

Related with the App Note: 
- 3.2 LPCD_FILTER tells that it samples 16 times during the RF on time. This algorithm increases the RF on time by the factor of two or three in case of instability.
- 3.7 LPCD features (CLRC663 plus only) tells that samples 64 times at the cost of a longer RF on time.
- 3.6 The LPCD detection: 3 µs ≤ tRFon ≤ 10 µs -> operation with TVDD = 5V, Charge pump enabled &
LPCD_FILTER enabled

So theoretically with a RFon time of 10us should be enough. We don't need to care about the RFon time, isn't it?

I add a picture where we've configured a RFon Time of 60us, the IRQ is configured only to change with a LPCDIrq. When we read the LPCD_Result_Q and I registers, the result value is 0x00.

Regards,
Iñaki