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Re: NFC/RFID Forum: TRF7970A NFC polling mode issue. receiving interrupt error

John,
 
 I'm running both the EVM_GUI and my C# code on the same Win7 machine. I noticed my code was slightly more likely to run properly on Win10.
 
 Then I noticed a bit was set in some commands and not others so I tried setting it and viola!!! Things started working again (I didn't mention my C# code was working until yesterday).
 
 Anyway when I changed the Inventory command from 010B000304140401000000 to 010B000304140601000000 it started to respond again. However, "\r\n" is at the head and not tail of the response now which is even more baffling???
 
What does that bit do?
 
Best Regards,
 
Dennis


Sep 29, 2015 06:08:58 PM, nfc_rfid@mail.e2e.ti.com wrote:

 

A Message from the TI E2E™ Community
Texas Instruments

 

John Crutchfield replied to TRF7970A NFC polling mode issue. receiving interrupt error.

Hey Dennis,

0xC0 is typically because either the MCU host is to slow to service the IRQ Status Register. It just means that by the time it was read, the RX was already started, or in really slow cases, already finished.

What is your SPI clock freq? 2MHz is typical.

Is there anything in your software causing large latency such as an operating system, etc?

Thanks,
JD

 

 

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  • Dennis - 

    Section 4 of this document has the request flag byte bits broken out

    this byte must match what you have the TRF79xx ISO control register set for. 

    for example, a 0x26 or 0x06 request flags byte (single slot vs. 16 slot, respectively) would correspond to the ISO Control Register setting of 0x02.

    if you had 0x04 for request flags byte and the ISO Control register set for 0x02, then you would be essentially setting up the system for failure, as you are configuring the reader for high tag data rate, but telling the tag to respond with low tag data rate.

  • Josh,
     
                    That’s helpful.
     
                    I’ll look at that tomorrow and set things on the same path…
     
                    Thanks!
     
                    Dennis