36
SLOS758G – DECEMBER 2011 – REVISED MARCH 2020
Product Folder Links:
Detailed Description
Copyright © 2011–2020, Texas Instruments Incorporated
The steps to enter direct mode follow, using SPI with SS communication method only as one example, as
direct modes are also possible with parallel and SPI without SS. The application must enter direct mode 0
to accommodate non-ISO standard compliant card type communications. direct mode can be entered at
any time, so that if a card type started with ISO standard communications, then deviated from the
standard after being identified and selected, the ability to go into direct mode 0 becomes very useful.
Step 1:
Configure pins I/O_0 to I/O_2 for SPI with SS
Step 2:
Set pin 12 of the TRF7963A (ASK/OOK pin) to 0 for ASK or 1 for OOK
Step 3:
Program the TRF7963A registers
The following registers must be explicitly set before going into direct mode.
1. ISO Control register (0x01) to the appropriate standard:
–
0x08 for ISO/IEC 14443 A (106 kbps)
–
0x1A for FeliCa 212 kbps
–
0x1B for FeliCa 424 kbps
2. Modulator and SYS_CLK Register (0x09) to the appropriate clock speed and modulation:
–
0x21 for 6.78-MHz clock and OOK (100%) modulation
–
0x20 for 6.78-MHz clock and ASK 10% modulation
–
0x22 for 6.78-MHz clock and ASK 7% modulation
–
0x23 for 6.78-MHz clock and ASK 8.5% modulation
–
0x24 for 6.78-MHz clock and ASK 13% modulation
–
0x25 for 6.78-MHz clock and ASK 16% modulation
See register 0x09 definition for all other possible values.
Example register setting for ISO/IEC 14443 A at 106 kbps:
–
ISO Control register (0x01) to 0x08
–
RX No Response Wait Time register (0x07) to 0x0E
–
RX Wait Time register (0x08) to 0x07
–
Modulator Control register (0x09) to 0x21 (or any custom modulation)
–
RX Special Settings register (0x0A) to 0x20
Step 4:
Enter direct mode
The following registers must be reprogrammed to enter direct mode:
1. Set bit B6 of the Modulator and SYS_CLK Control register (0x09) to 1.
2. Set bit B6 of the ISO Control register (0x01) to 0 for direct mode 0 (default its 0)
3. Set bit B6 of the Chip Status Control register (0x00) to 1 to enter direct mode (do not send a Stop
condition after this command)
NOTE
•
Do not terminate last write with a Stop condition. For SPI, this means that Slave Select
(I/O_4) continues to stay low.
•
Sending a Stop condition terminates the direct mode and clears bit B6 in the Chip Status
Control register (0x00).
NOTE
Access to registers, FIFO, and IRQ is not available during direct mode 0.
Remember that the reader enters direct mode 0 when bit 6 of the Chip Status Control register (0x00) is
set to a 1, and it stays in direct mode 0 until a Stop condition is sent from the microcontroller.
