MAX86140 datasheet(39/89 Pages) MAXIM

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GPIO CTRL[3:0] 0110 and 1000: Master/Slave with and without External Mux

Table 13. GPIO Mode 0110 and 1000

GPIO

CTRL

GPIO1

FUNCTION

GPIO2

FUNCTION

COMMENT

0110

Input

Exposure

Trigger

Tristate or

Mux Control

GPIO1 is defined as an exposure trigger input (Slave). This input can come from an

external source or from another MAX86140/MAX86141 in master sample mode. Both

sample and exposure timing is controlled by the GPIO1 input. GPIO2 will be active if any

of the LEDCn[3:0] states A, B, or C are enabled in the exposure sequence. In this case,

GPIO2 will be low during exposures on LED4, LED5, or LED6, otherwise it will be high.

If LEDCn[3:0] state A, B, or C is not enabled in the exposure sequence, GPIO2 will be

tristate unless externally pulled up.

1000

Active

Output

Master

Exposure

Output

Input

32768/32000Hz

Clock Input

GPIO1 is defined as a master sample output. The GPIO1 output can be used to trigger

and second sensor. When used with a second MAX86140 /MAX86141 set to slave

exposure mode, the master exposure timing will drive slave exposure time. GPIO2 is an

input 32768/32000Hz. Sample and exposure timing is controlled by GPIO2 clock input.

Figure 25. Timing Diagram for GPIO CTRL[3:0] 0110 and 0111 With External Mux

LED1_DRV

MASTER & SLAVE

LED2_DRV

MASTER & SLAVE

tPW

LED3_DRV

MASTER & SLAVE

tPW

GPIO1

MASTER

tPW

GPIO2

MASTER & SLAVE

tSAMPLE

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MAX86140 Datasheet(PDF) 39 Page - Maxim Integrated Products

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