TRF7970A no flag in IRQ Status Register

Hello,

I have a problem with the TRF7970A, this works in card emulation mode.

My Initialization:
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directCommand send whit "0x03 Software Initialization"
directCommand send whit "0x00 Idle"
delay_ms(3)

Chip Status Control Register (0x00) => 0x21
ISO Control Register (0x01) => 0x24

directCommand send whit "0x0F Reset"

ISO14443B TX Options Register (0x02) => 0x00
Modulator and SYS_CLK Control Register (0x09) => 0x01
RX Special Setting Register (0x0A) => 0x30
Regulator and I/O Control Register (0x0B) => 0x87
FIFO IRQ Levels Register (0x14) => 0x0F
NFC Low Field Level Register (0x16) => 0x83


NFCID1 Number Register (0x17) is set with 7Byte ID


Special Functions Register (0x10) => 0x0A
NFC Target Detection Level Register (0x18) => 0x67
Interrupt Mask Register (0x0D) => 0x3E

directCommand send whit "0x0F Reset"

directCommand send whit "0x16 Block Receiver"
directCommand send whit "0x17 Enable Receiver"

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The problem is, if no or incorrect CRC-Bytes are received, the IRQ-Status-Register (0x0C) is 0x00, no flag is set.
But an IRQ interrupt is send to the MCU.
At a SDD, TX or RX interrupt the IRQ-Status-Register is set correctly.

Thanks!
Patrick