поискавой системы для электроныых деталей |
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FM33256-G датащи(PDF) 8 Page - Ramtron International Corporation |
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FM33256-G датащи(HTML) 8 Page - Ramtron International Corporation |
8 / 28 page FM33256/FM3316 SPI Companion w/ FRAM Rev. 1.0 Dec. 2006 Page 8 of 28 Table 3. Alarm Match Bit Examples Seconds Minutes Hours Date Months Alarm condition 1 1 1 1 1 No match required = alarm 1/second 0 1 1 1 1 Alarm when seconds match = alarm 1/minute 0 0 1 1 1 Alarm when seconds, minutes match = alarm 1/hour 0 0 0 1 1 Alarm when seconds, minutes, hours match = alarm 1/date 0 0 0 0 1 Alarm when seconds, minutes, hours, date match = alarm 1/month Real-time Clock Operation The real-time clock (RTC) is a timekeeping device that can be capacitor- or battery-backed for permanently-powered operation. It offers a software calibration feature that allows high accuracy. The RTC consists of an oscillator, clock divider, and a register system for user access. It divides down the 32.768 kHz time-base and provides a minimum resolution of seconds (1Hz). Static registers provide the user with read/write access to the time values. It includes registers for seconds, minutes, hours, day- of-the-week, date, months, and years. A block diagram shown in Figure 9 illustrates the RTC function. The user registers are synchronized with the timekeeper core using R and W bits in register 00h. The R bit is used to read the time. Changing the R bit from 0 to 1 transfers timekeeping information from the core into the user registers 02-08h that can be read by the user. If a timekeeper update is pending when R is set, then the core will be updated prior to loading the user registers. The user registers are frozen and will not be updated again until the R bit is cleared to a ‘0’. The W bit is used to write new time/date values. Setting the W bit to a ‘1’ stops the RTC and allows the timekeeping core to be written with new data. Clearing it to ‘0’ causes the RTC to start running based on the new values loaded in the timekeeper core. The RTC may be synchronized to another clock source. On the 8 th clock of the write to register 00h (W=0), the RTC starts counting with a timebase that has been reset to zero milliseconds. Note: Users should be certain not to load invalid values, such as FFh, to the timekeeping registers. Updates to the timekeeping core occur continuously except when locked. Figure 9. Real-time Clock Core Block Diagram 32.768 kHz crystal Oscillator Clock Divider Update Logic 512 Hz or SW out W R Seconds 7 bits Minutes 7 bits Hours 6 bits Date 6 bits Months 5 bits Years 8 bits CF Days 3 bits User Registers 1 Hz /OSCEN |
Аналогичный номер детали - FM33256-G |
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Аналогичное описание - FM33256-G |
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