Texas Instruments TRF7970A Manual page 53

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Table 6-19. Address and Command Word Bit Distribution (continued)
COMMAND
CODE
0x19 Test external RF (RSSI at RX input with TX on)
The command code values from
significant bit (MSB) in
for easy reference).
BIT
B7
B6
B5 Continuous address mode
B4 Address/Command bit 4
B3 Address/Command bit 3
B2 Address/Command bit 2
B1 Address/Command bit 1
B0 Address/Command bit 0
The MSB determines if the word is to be used as a command or address. The last two columns of
Table 6-20 show the function of each bit, depending on whether address or command is written.
Command mode is used to enter a command resulting in reader action (initialize transmission, enable
reader, and turn reader on or off).
6.14.1.1 Idle (0x00)
This command issues dummy clock cycles. In parallel mode, one cycle is issued. In SPI mode, eight
cycles are issued. This command should be sent after a Software Initialization command to allow the
command to finish operation.
6.14.1.2 Software Initialization (0x03)
This command starts a power-on reset. After sending this command, the register values change as shown
in Table 6-21.
Copyright © 2011–2017, Texas Instruments Incorporated
COMMAND
Table 6-19
Table 6-20 must be set to 1.
Table 6-20. Address and Command Word Bit Distribution
DESCRIPTION
Command control bit
Read/Write
Table 6-21. Register Values After Sending Software
Initialization (0x03)
ADDRESS
0x00 Chip status control
0x01 ISO control
0x02 ISO/IEC 14443 B TX options
0x03 ISO/IEC 14443 A high bit rate options
0x04 TX timer high byte control
0x05 TX timer low byte control
0x06 TX pulse length control
0x07 RX no response wait time
0x08 RX wait time
0x09 Modulator and SYS_CLK control
0x0A RX special setting
(1) Differs from default at POR
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are substituted in Table 6-20, bits 0 through 4. Also, the most-
(Table 6-20 is same as
BIT FUNCTION
0 = Address
1 = Command
0 = Write
1 = Read
1 = Continuous mode
REGISTER
TRF7970A
COMMENTS
Table 6-11, shown here again
ADDRESS COMMAND
0
R/W
R/W
Adr 4
Adr 3
Adr 2
Adr 1
Adr 0
VALUE
0x01
(1)
0x21
0x00
0x00
(1)
0xC1
(1)
0xC1
0x00
0x0E
(1)
0x07
0x91
(1)
0x10
Detailed Description
TRF7970A
1
0
0
Cmd 4
Cmd 3
Cmd 2
Cmd 1
Cmd 0
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