Description¶

This driver implements support for the Texas Instruments ADC128D818.It is described as ‘ADC System Monitor with Temperature Sensor’.

The ADC128D818 implements one temperature sensor and seven voltage sensors.

Temperatures are measured in degrees Celsius. There is one set of limits.When the HOT Temperature Limit is crossed, this will cause an alarm that willbe reasserted until the temperature drops below the HOT Hysteresis.Measurements are guaranteed between -55 and +125 degrees. The temperaturemeasurement has a resolution of 0.5 degrees; the limits have a resolutionof 1 degree.

Voltage sensors (also known as IN sensors) report their values in volts.An alarm is triggered if the voltage has crossed a programmable minimumor maximum limit. Note that minimum in this case always means ‘closest tozero’; this is important for negative voltage measurements. All voltageinputs can measure voltages between 0 and 2.55 volts, with a resolutionof 0.625 mV.

If an alarm triggers, it will remain triggered until the hardware registeris read at least once. This means that the cause for the alarm mayalready have disappeared by the time the alarm is read. The drivercaches the alarm status for each sensor until it is at least reportedonce, to ensure that alarms are reported to user space.

The ADC128D818 only updates its values approximately once per second;reading it more often will do no harm, but will return ‘old’ values.

In addition to the scanned address list, the chip can also be configured foraddresses 0x35 to 0x37. Those addresses are not scanned. You have to instantiatethe driver explicitly if the chip is configured for any of those addresses inyour system.