ZSSC3123AI2 datasheet(34/63 Pages) IDT

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ZSSC3123 Datasheet

January 26, 2016

Device Slave Address [6:0]

Cap. Data [13:8]

Cap. Data [7:0]

Cap. Data [13:8]

Cap. Data [7:0]

Temp. Data [13:6]

Slave Address Bit (Example: Bit 2)

Command or Data Bit (Example: Bit 2)

Status Bit

Start Condition

Stop Condition

Acknowledge (ACK)

Not Acknowledge

Read/Write

(NACK)

(Read = 1)

Wait for

Slave ACK

Master ACK

Master NACK

2 C DF – 2 Bytes: Slave returns only capacitance data to master in 2 bytes

14 13

1 0

5 4

A 15

2 1

14 13

1 0

6 5

1 0

Device Slave Address [6:0]

2 C DF – 3 Bytes: Slave returns 2 capacitance data bytes & temperature high byte (T[13:6]) to master

3.6.4

Data Fetch (DF)

The Data Fetch (DF) command is used to fetch data in any digital output mode. With the start of communication (for I

2C™

after reading the slave address; for SPI at the falling edge of SS) the entire output packet will be loaded in a serial output

register. The register will be updated after the communication is finished. The output is always scaled to 14 bits independent of

the programmed resolution. The ordering of the bits is big-endian.

3.6.4.1.

2C™ Data Fetch

An I

2C™ Data Fetch command starts with the 7-bit slave address and the 8th bit = 1 (READ). The ZSSC3123 as the slave

sends an acknowledge (ACK) indicating success. The number of data bytes returned by the ZSSC3123 is determined by when

the master sends the NACK and stop condition. Figure 3.10 shows examples of fetching two and three bytes respectively. The

full 14 bits of capacitive data are fetched in the first two bytes. The MSBs of the first byte are the status bits.

If temperature data is needed, additional temperature bytes can be fetched. In Figure 3.10, the three-byte data fetch returns 1

byte of temperature data (8-bit accuracy) after the capacitive data. A fourth byte can be fetched where the six MSBs of the

fetched byte are the six LSBs of a 14-bit temperature measurement. The last two bits of the fourth byte are undetermined and

should be masked off in the application.

Figure 3.10

2C™ Measurement Packet Reads

3.6.4.2.

SPI Data Fetch

By default the SPI interface will have data change after the falling edge of SCLK. The master should sample MISO on the

rising (opposite) edge of SCLK. This is configurable via the SPI_Phase bit in EEPROM word Cust_Config (see Table 5.5 for bit

assignments). The SPI protocol can handle high and low polarity of the clock line without configuration change.

ZSSC3123AI2 Datasheet(PDF) 34 Page - Integrated Device Technology

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