User's Manual

TRF7970A
www.ti.com SLOS743K –AUGUST 2011–REVISED APRIL 2014
6.12.2 Initiator
The chip is fully controlled by the MCU as in RFID reader operation. The MCU activates the chip and
writes the mode selection in the ISO Control register. The MCU uses RF collision avoidance commands,
so it is relieved of any real-time task. The normal transmit and receive procedure (through the FIFO) are
used to communicate with the TARGET device as described in Section 6.10.
6.13 Direct Commands from MCU to Reader
6.13.1 Command Codes
Table 6-19. Address and Command Word Bit Distribution
Command Code Command Comments
0x00 Idle
0x03 Software Initialization Same as Power on Reset
0x04 Perform RF Collision Avoidance
0x05 Perform response RF Collision Avoidance
0x06 Perform response RF Collision Avoidance (n = 0)
0x0F Reset
0x10 Transmission without CRC
0x11 Transmission with CRC
0x12 Delayed Transmission without CRC
0x13 Delayed Transmission with CRC
0x14 End of Frame/Transmit Next Time Slot ISO15693
0x15 Close Slot Sequence
0x16 Block Receiver
0x17 Enable Receiver
0x18 Test internal RF (RSSI at RX input with TX off)
0x19 Test external RF (RSSI at RX input with TX on)
0x1A Receiver Gain Adjust
The command code values from Table 6-19 are substituted in Table 6-20, Bits 0 through 4. Also, the
most-significant bit (MSB) in Table 6-20 must be set to 1. ( Table 6-20 is same as Table 6-11, shown here
again for user clarity).
Table 6-20. Address and Command Word Bit Distribution
Bit Description Bit Function Address Command
0 = address
B7 Command control bit 0 1
1 = command
0 = write
B6 Read/Write R/W 0
1 = read
B5 Continuous address mode 1 = Continuous mode R/W 0
B4 Address/Command bit 4 Adr 4 Cmd 4
B3 Address/Command bit 3 Adr 3 Cmd 3
B2 Address/Command bit 2 Adr 2 Cmd 2
B1 Address/Command bit 1 Adr 1 Cmd 1
B0 Address/Command bit 0 Adr 0 Cmd 0
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