Sun Microsystems S16A manual Analog Input Module UART Registers, Temperature Register

Registers S16A User’s Guide

Trim Input Gain Registers

These two trim registers control the fine-tuning of the analog I/O input gain. Trim register 4 controls the gain trim for analog I/O channel 0 input; trim register 6 controls the gain trim for channel 1 input. The input offset should be set using a zero-level input signal before setting the input gain.

Trim Input Offset Registers

These two trim registers control the fine-tuning of the input gain. Trim register 5 controls the input offset for analog I/O channel 0; trim register 7 controls the input offset for analog I/O channel 1.

The recommended procedure for adjusting these input trim registers is to connect it to the signal source, set the source to generate a zero-level signal, and then adjust the input offset while monitoring the input data for zero. The input offset trim should be set using a zero-level input signal before configuring the input gain and input gain trim settings.

Temperature Register

The S16A contains an internal temperature probe that can be read via the Analog Input Module UART interface to provide data for temperature-dependent calibration adjustments. This two-byte register returns a 12-bit reading that can be converted to a Celsius temperature using the formula

C = ((5.0 * (r / 4096)) - 1.375) * 0.0225

where

ris the raw temperature reading, and

Cis the resulting Celsius temperature.

As an Analog Input Module register, this register is accessed via the UART registers.

Analog Input Module UART Registers

The S16A Analog Input Module is configured and controlled by a byte stream protocol via two UART registers on the SBus. Command sequences of bytes are sent to the module, which in turn responds with byte sequences. Two interface registers, the UART CSR and the UART Data register, implement this byte stream interface on the SBus.

Analog Input Module Control Protocol

All command and status sequences consist entirely of printable ASCII characters. Commands are case- insensitive. The command character is always echoed; valid arguments are also echoed; invalid argument characters are ignored. Commands are not terminated with a carriage return or newline: when the last character of the command is sent, the command is immediately executed and the response string is sent back.

34 EDT, Inc. October, 1996