GC1115 Datasheet, PDF (41/80 Pages) Texas Instruments – Crest Factor Reduction Processor

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TIMER_LO_RST 0xE (14) Type: Read/Write Value at RESET: 0x0000
GC1115
SLWS144 – FEBRUARY 2005
The TIMER_LO_RST and TIMER_HI_RST registers (each 16 bits wide) determine the reset value of the
GC1115’s programmable software timer. This timer can be enabled to control the occurrence of SYNC events
during GC1115 processing. TIMER_HI_RST and TIMER_LO_RST are combined into a 32-bit unsigned value
which is clocked with every internal GC1115 clock. The TIMER_HI_RST and TIMER_LO_RST registers operate
in conjunction with the TIMER_SYNC register.
BITS
[15:0]
DESCRIPTION
Lower 16 bits of the GC1115’s 32-bit timer reset value.
Cancellation Coefficient Registers (Addresses 15 – 20)
CANCEL_MODE 0xF (15) Type: Read/Write Value at RESET: 0x0000
The CANCEL_MODE register sets the characteristics of the cancellation coefficients. The GC1115 operates
using either real (symmetric carrier spectra) or complex (asymmetric carrier spectra) cancellation coefficients. For
symmetric spectra, the cancellation coefficients can also be unique or mirrored. Mirrored coefficients are only
needed when a cancellation pulse with more than 255 coefficients is desired. [Note: cancellation pulses with
about 100 unique coefficients are more than adequate to meet all 3G or cdma2000 requirements]. Mirrored
mode is also useful because only half of the coefficients need be downloaded, thus shortening the time required
to provide the GC1115 with a new set of cancellation coefficients. When mirrored mode is used, the GC1115
applies N real cancellation coefficients in the following order:
coef[0], coef[1], …, coef[N-2], coef[N-1], coef[N-2], …, coef[1], coef[0]
Bits [11:8] of CANCEL_MODE contain a peak hysteresis (timeout) count whose value is determined during
cancellation pulse design. Under most operating conditions, the hysteresis count is zero. However, for some
configurations with large gaps between carriers (“missing” carriers), the hysteresis count will have a non-zero
value of 6 or less. Please contact TI to determine how to calculate the peak hysteresis count for your cancellation
coefficients.
BITS
0
1
[7:2]
[11:8]
[15:12]
DESCRIPTION
Cancel coef format
0 = real
1 = complex
Mirrored coefs
0 = unique
1 = mirrored
Reserved
Peak hysteresis count (0
to 6)
Reserved
41