AS7058 datasheet(50/199 Pages) AMSOSRAM

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AS7058

Functional description

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In response to that stimulus, the voltages at the ECG input will change and depend on the

impedances between electrodes and skin. These voltages can be measured by MOD3 directly

via the modulator input multiplexer that can be configured via ECGMOD_IMUX_SEL2 register

like it is shown in Figure 42. The output of MOD3 is connected to a digital comparator which

can be programmed with a certain threshold (LEADOFF_TH_RES) for the leadoff detection to

create an interrupt for host notification. There is also an oversampling function implemented

which can be configured via LEADOFF_OVS register. Its value defines how many ADC

readings must be above or below the defined threshold that a lead off condition is detected

and an interrupt is generated. In addition to the oversampling function it is also possible to

configure if the comparator triggers on the positive and negative edge of the lead off signal.

This function can be configured with the register LEADOFF_EDGE. A simplified timing

diagram which shows the use of the oversampling function is shown in Figure 43. In case of a

rising edge of the ECG input signal voltage which is four times above the threshold value the

LEADOFF_ON register bit is set and an interrupt (IRQ_LEADOFF) is released. The interrupt

as well as the lead off status bits are cleared once the STATUS_LEADOFF register is read.

Figure 43: Lead off detection timing diagram

Lead-Off Threshold

LEADOFF_TH_RES[15:0]

Lead-Off Oversampling

LEADOFF_OVS[2:0]

Lead-Off Edge Detection

LEADOFF_EDGE<1:0>

Lead-Off OnStatus Register

LEADOFF_ON

Lead-Off Off Status Register

LEADOFF_OFF

LEADOFF_OVS = 0x04

LEADOFF_EDGE = 0x03

Proximity Interrupt

IRQ_LEADOFF

Read

STATUS_LEADOFF[2:0]

Read

STATUS_LEADOFF[2:0]

AS7058 Datasheet(PDF) 50 Page - ams-OSRAM AG