ZSSC3123AI2 datasheet(36/63 Pages) IDT

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ZSSC3123 Datasheet

January 26, 2016

SCLK

MISO

Ignore Data

Device Slave Address [6:0]

5 4

A S

Wait for

Slave ACK

Start Condition

Stop Condition

Acknowledge (ACK)

Slave Address Bit

Read/Write bit

(Example: Bit 2)

(Example: Write = 0)

2C MR– Measurement Request: Slave starts a measurement cycle

Figure 3.12

2C™ MR

3.6.5.2.

SPI Measurement Request

The SPI MR is used to wake up the device in Sleep Mode and start a complete measurement cycle starting with a temperature

measurement/temperature DSP calculation, followed by a capacitance measurement / capacitance DSP calculations, and then

the results are written to the digital output register. As shown in Figure 3.13, executing an SPI MR command is a read of 8 bits,

ignoring the data that is returned.

Note: The SPI MR function can also be accomplished by performing a full SPI Data Fetch (see section 3.6.4.2) and ignoring

the invalid data that will be returned.

Figure 3.13

SPI MR

3.6.6

Ready Pin

A rise on the Ready pin indicates that new data is ready to be fetched from either the I

2C™ or SPI interface. The Ready pin

stays high until a Data Fetch (DF) command is sent (see section 3.6.3); it stays high even if additional measurements are

performed before the DF. In Sleep Mode, sending a Measurement Request (MR) command resets the Ready pin.

The Ready pin’s output driver type is selectable as either full push-pull or open drain via the Ready_Open_Drain bit in

EEPROM word Cust_Config (see Table 5.5 for bit assignments and settings). Point-to-point communication most likely uses

the full push-pull driver. If an application requires interfacing to multiple parts, then the open drain option can allow for just one

wire and one pull-up resistor to connect all the parts in a bus format.

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