RTEMS 6.1-rc7
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Real Time Clock
  • It would be nice to utilize the interrupt capabilities of some RTC parts. This could be used to trigger checking the software clock against the hardware clock.
  • The periodic capability of most RTCs is not suitable for use as a general purpose flexible clock tick source. For example, many RTCs generate only a handful of periods with 100 Hz being the most frequent.
  • The tick field is not set on get. Anything smaller than a second is ignored on set and get operations.
  • Day of week is ignored since RTEMS does not set it internally.
  • There is no attempt in RTEMS to know about time zones.

Harris ICM7170

  • Tested on a DMV177.
  • Interrupt capabilities are ignored.

Mostek 48T08

  • Untested.
  • NVRAM is ignored.

ds1643

The Mostek M48T08 is compatible with the Dallas Semiconductor DS1643. Please use that driver.

icm7170 Configuration Table Use

sDeviceName

The name of this device.

deviceType

This field must be RTC_ICM7170.

pDeviceFns

The device interface control table. This must be icm7170_fns.

deviceProbe

This is the address of the routine which probes to see if the device is present.

pDeviceParams

This field specifies the clock frequency.  It may be one of the
following:
    ICM7170_AT_32_KHZ
    ICM7170_AT_1_MHZ
    ICM7170_AT_2_MHZ
    ICM7170_AT_4_MHZ

ulCtrlPort1

This field is the base address of the RTC area of the chip.

ulCtrlPort2

This field is ignored.

ulDataPort

This field is ignored.

getRegister setRegister

These follow standard conventions.

m48t08 Configuration Table Use

sDeviceName

The name of this device.

deviceType

This field must be RTC_M48T08.

pDeviceFns

The device interface control table. This must be m48t08_fns.

deviceProbe

This is the address of the routine which probes to see if the device is present.

pDeviceParams

This is ignored and should be NULL.

ulCtrlPort1

This field is the base address of the RTC area of the chip. The NVRAM portion of the chip is ignored.

ulCtrlPort2

This field is ignored.

ulDataPort

This field is ignored.

getRegister setRegister

These follow standard conventions.

m48t18

This is supported by the m48t08 driver.

mc146818a

This is supported by the mc146818a driver.