User Manual

pg. 8

Figure 6 DAQ Connection Requirements

2.3 I

C Interface

The SingleTact I

C interface supports the standard (100 Kbits/s) clock rate in 7-bit address mode.

The SCL and SDA lines must be pulled up to the bus voltage which can be between 3V and 5V.

Please refer to the I2C specification for bus protocol implementation & pull-up value considerations.

The interface board will always respond to two I

C addresses: 0x04 and the address specified in

flash (register address 0). As shipped the default flash address is also 0x04.

Multiple sensor interfaces may be connected to a single I

C bus. The bus address of individual

sensor interfaces can be configured by writing desired address value (4 to 127) via the I

C interface

to register address 0 with an I2C Write Operation. Change of individual sensor I

C addresses is

supported by the PC and Arduino Example.

NOTE: As the interface board will always respond to address 0x04 then this address must be

considered reserved for SingleTact. Where multiple SingleTact interfaces are to be connected to the

same I

C bus then address 0x04 must be considered invalid and in this use case the configurable

address of all connected SingleTact nodes must be individually changed from the default value before

each SingleTact is added to the multi-node bus.

The SingleTact software architecture is based on a 192 byte register block – see Figure 7 and

Table 2 for details.

All control registers are located in first 112 bytes and get written to NVM when modified (and are

therefore persistent after a power cycle). Configuration registers on Calibrated sensors interfaces are

protected from modification.

The sensor results are available from bytes 128 to 133. As shipped, results are updated at >140Hz

(this is dependent on capacitance sensor settings).

CONNECTION

No Connect

Ground

CONNECTION

No Connect

Analog Out

Vcc

NUMBER