SBAS774B May 2016 – December 2021 ADC32RF80 , ADC32RF83
PRODUCTION DATA
In this detector mode, the peak is computed over eight samples of the ADC output. Next, the peak for a block of N samples (N × S`) is computed over a programmable block length and then compared against a threshold to either set or reset the peak detector output (Figure 8-46 and Figure 8-47). There are two sets of thresholds and each set has two thresholds for hysteresis. The programmable DWELL-time counter is used for clearing the block detector alarm output.
Table 8-9 shows the register configurations required to set up the absolute peak power detector. The detector operates in the fS / 8 clock domain; one peak sample is calculated over eight actual samples.
The automatic gain control (AGC) modes can be configured separately for channel A (54xxh) and channel B (5Cxxh), although some registers are common in 54xxh (such as the GPIO pin selection).
REGISTER | ADDRESS | DESCRIPTION |
---|---|---|
PKDET EN | 5400, 5C00h | Enables peak detector |
BLKPKDET | 5401h, 5402h, 5403h, 5C01h, 5C02h, 5C03h | Sets the block length N of number of samples (S`). Number of actual ADC samples is 8x this value: N is 17 bits: 1 to 216. |
BLKTHHH, BLKTHHL, BLKTHLH, BLKTHLL | 5407h, 5408h, 5409h, 540Ah, 5C07h, 5C08h, 5C09h, 5C0Ah | Sets the different thresholds for the hysteresis function values from 0 to 256 (where 256 is equivalent to the peak amplitude). For example: if BLKTHHH is to –2 dBFS from peak, 10(–2 / 20) × 256 = 203, then set 5407h and 5C07h = CBh. |
DWELL | 540Bh, 540Ch, 5C0Bh, 5C0Ch | When the computed block peak crosses the upper thresholds BLKTHHH or BLKTHLH, the peak detector output flags are set. In order to be reset, the computed block peak must remain continuously lower than the lower threshold (BLKTHHL or BLKTHLL) for the period specified by the DWELL value. This threshold is 16 bits and is specified in terms of fS / 8 clock cycles. |
OUTSEL GPIO[4:1] | 5432h, 5433h, 5434h, 5435h | Connects the BLKPKDETH, BLKPKDETL alarms to the GPIO pins; common register. |
IODIR | 5437h | Selects the direction for the four GPIO pins; common register. |
RESET AGC | 542Bh, 5C2Bh | After configuration, reset the AGC module to start operation. |