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Moteur de recherche de fiches techniques de composants électroniques |
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FM3135 Fiches technique(PDF) 6 Page - Ramtron International Corporation |
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FM3135 Fiches technique(HTML) 6 Page - Ramtron International Corporation |
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6 / 21 page  FM3135 Integrated RTC/Alarm/FRAM & Embedded Crystal Rev. 1.2 Feb. 2009 Page 6 of 21 26 512.0567 512.0589 110.68 115.01 011010 27 512.0589 512.0611 115.02 119.35 011011 28 512.0611 512.0633 119.36 123.69 011100 29 512.0633 512.0656 123.70 128.03 011101 30 512.0656 512.0678 128.04 132.37 011110 31 512.0678 512.0700 132.38 136.71 011111 Alarm The alarm function compares user-programmed alarm values to the corresponding RTC time/date values. When a match occurs, an alarm event occurs. The alarm event sets an internal flag AF (register 00h, bit 6) and drives the ACS pin low, if the appropriate control bits are set in registers 00h and 0Eh. See Table 3. The alarm condition on the ACS pin and the AF bit are cleared by reading register 00h. The alarm operates under VDD or VBAK power. If the system controller is being used to detect an alarm while the FM3135 is powered on VBAK only, the ACS pin may cause extra IBAK current when the alarm is activated. To avoid battery drain, the ACS pin can be tri-stated by reading the AF flag, located in the RTC/Alarm Control register 00h. There are five alarm match fields. They are Month, Date, Hours, Minutes, and Seconds. Each of these fields also has a Match bit that is used to determine if the field is used in the alarm match logic. Setting the Match bit to ‘0’ indicates that the corresponding field will be used in the match process. Depending on the Match bits, the alarm can occur as specifically as one particular second on one day of the month, or as frequently as once per second continuously. The MSB of each Alarm register is a Match bit. Examples of the Match bit settings are shown in Table 4. Alarm Match Bit Examples. Selecting none of the match bits (all ‘1’s) indicates that no match is required. The alarm occurs every second. Setting the match select bit for seconds to ‘0’ causes the logic to match the seconds alarm value to the current time of day. Since a match will occur for only one value per minute, the alarm occurs once per minute. Likewise setting the seconds and minutes match select bits causes an exact match of these values. Thus, an alarm will occur once per hour. Setting seconds, minutes, and hours causes a match once per day. See Table 4 for other alarm setting examples. Function of the ACS Pin The ACS pin is a multifunction pin. The alarm, calibration, and square wave functions all share this output. There are two ways a user can detect an alarm event, by reading the AF flag or by monitoring the ACS pin. An interrupt pin on the host processor may be used to detect an alarm event. The AF flag in the register 00h (bit 6) will indicate that a time/date match has occurred. When a match occurs, the AF bit will be set to ‘1’ and the ACS pin will drive low. The flag and ACS pin will remain in this state until the RTC/Alarm Control register is read which clears the AF bit. Table 3 that shows the relationship between register control settings and the function of the ACS pin. Table 3. Control Bit Settings for ACS Pin State of Register Bit Function of ACS pin CAL AEN AL/SW 0 1 1 /Alarm 0 X 0 Sq Wave out 1 X X 512 Hz out 0 0 1 Hi-Z |
Numéro de pièce similaire - FM3135 |
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Description similaire - FM3135 |
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