Datasheet

AFE4490

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SBAS602F –DECEMBER 2012–REVISED OCTOBER 2013

PRPCOUNT: Pulse Repetition Period Count Register (Address = 1Dh, Reset Value = 0000h)

D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12

0 0 0 0 0 0 0 0 PRPCOUNT[15:0]

D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

PRPCOUNT[15:0]

This register sets the device pulse repetition period count.

Bits D[23:16] Must be '0'

Bits D[15:0] PRPCOUNT[15:0]: Pulse repetition period count

The contents of this register can be used to set the pulse repetition period (in number of

clock cycles of the 4-MHz clock). The PRPCOUNT value must be set in the range of 800 to

64000. Values below 800 do not allow sufficient sample time for the four samples; see the

Electrical Characteristics table.

CONTROL1: Control Register 1 (Address = 1Eh, Reset Value = 0000h)

D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12

0 0 0 0 0 0 0 0 0 0 0 0

D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

CLKALMPIN[2:0] TIMEREN NUMAV[7:0]

This register configures the clock alarm pin, timer, and number of averages.

Bits D[23:12] Must be '0'

Bits D[11:9] CLKALMPIN[2:0]: Clocks on ALM pins

Internal clocks can be brought to the PD_ALM and LED_ALM pins for monitoring.

Note that the ALMPINCLKEN register bit must be set before using this register bit. Table 6

defines the settings for the two alarm pins.

Bit D8 TIMEREN: Timer enable

0 = Timer module is disabled and all internal clocks are off (default after reset)

1 = Timer module is enabled

Bits D[7:0] NUMAV[7:0]: Number of averages

Specify an 8-bit value corresponding to the number of ADC samples to be averaged – 1.

For example, to average four ADC samples, set NUMAV[7:0] equal to 3.

Table 6. PD_ALM and LED_ALM Pin Settings

CLKALMPIN[2:0] PD_ALM PIN SIGNAL LED_ALM PIN SIGNAL

000 Sample LED2 pulse Sample LED1 pulse

001 LED2 LED pulse LED1 LED pulse

010 Sample LED2 ambient pulse Sample LED1 ambient pulse

011 LED2 convert LED1 convert

100 LED2 ambient convert LED1 ambient convert

101 No output No output

110 No output No output

111 No output No output

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