Texas Instruments TRF7970A Manual page 62

TRF7970A
SLOS743L – AUGUST 2011 – REVISED MARCH 2017
6.15.3.2.5 TX Pulse Length Control Register (0x06)
The length of the modulation pulse is defined by the protocol selected in the ISO Control register 0x01.
With a high Q antenna, the modulation pulse is typically prolonged, and the tag detects a longer pulse
than intended. For such cases, the modulation pulse length can be corrected by using the TX Pulse
Length Control register (0x06). If the register contains all zeros, then the pulse length is governed by the
protocol selection. If the register contains a value other than 0x00, the pulse length is equal to the value of
the register in 73.7-ns increments. This means the range of adjustment can be 73.7 ns to 18.8 µs.
Table 6-33 describes the TX Pulse Length Control register.
Function: Controls the length of TX pulse
Default: 0x00 at POR = H or EN = L and at each write to ISO Control register.
Bit Name
B7 Pul_p2 Pulse length MSB
B6 Pul_p1
B5 Pul_p0
B4 Pul_c4
B3 Pul_c3
B2 Pul_c2
B1 Pul_c1
B0 Pul_c0 Pulse length LSB
6.15.3.2.6 RX No Response Wait Time Register (0x07)
The RX No Response timer is controlled by the RX NO Response Wait Time Register 0x07. This timer
measures the time from the start of slot in the anticollision sequence until the start of tag response. If there
is no tag response in the defined time, an interrupt request is sent and a flag is set in IRQ status control
register 0x0C. This enables the external controller to be relieved of the task of detecting empty slots. The
wait time is stored in the register in increments of 37.76 µs. This register is also preset, automatically, for
every new protocol selection. Sending a Reset FIFO (0x0F) direct command after a TX Complete interrupt
will disable this feature.
Table 6-34 describes the RX No Response Wait Time register.
Function: Defines the time when "no response" interrupt is sent; only for ISO/IEC 15693
Default: 0x0E at POR = H or EN = L and at each write to ISO Control register
Bit Name
B7 NoResp7 No response MSB
B6 NoResp6
B5 NoResp5
B4 NoResp4
B3 NoResp3
B2 NoResp2
B1 NoResp1
B0 NoResp0 No response LSB
62 Detailed Description
Table 6-33. TX Pulse Length Control Register (0x06)
Function
The pulse range is 73.7 ns to 18.8 µs (1....255), step size 73.7 ns.
All bits low (00): pulse length control is disabled.
The following default timings are preset by the ISO Control register (0x01):
9.44 µs → ISO/IEC 15693 (TI Tag-It HF-I)
11 µs → Reserved
2.36 µs → ISO/IEC 14443 A at 106 kbps
1.4 µs → ISO/IEC 14443 A at 212 kbps
737 ns → ISO/IEC 14443 A at 424 kbps
442 ns → ISO/IEC 14443 A at 848 kbps; pulse length control disabled
Table 6-34. RX No Response Wait Time Register (0x07)
Function
Defines the time when "no response" interrupt is sent. It starts from the end of
TX EOF. RX no response wait range is 37.76 µs to 9628 µs (1 to 255), step
size is: 37.76 µs.
The following default timings are preset by the ISO Control register (0x01):
390 µs → Reserved
529 µs → for all protocols supported, but not listed here
604 µs → Reserved
755 µs → ISO/IEC 15693 high data rate (TI Tag-It HF-I)
1812 µs → ISO/IEC 15693 low data rate (TI Tag-It HF-I)
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