A Hz crystal is required to provide the correct timing. Data can be de- livered 1 byte at a time burst bytes Unit 5. Refer to the table shown below and follow the steps to write the data to the chip.

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The number of days in each month and leap years are automatically adjusted. A Hz crystal is required to provide the correct timing. Data can be delivered 1 byte at a time or in a burst of up to 8 bytes. Pad Description Pad No. Stresses exceeding the range specified under? Absolute Maximum Ratings? Functional operation of this device at other conditions beyond those listed in the specification is not implied and prolonged exposure to extreme conditions may affect device reliability.

Input Voltage? The clock halt bit must be set to logic 1 oscillator disabled. Data contained in the clock register is in binary coded decimal format. Two modes are available for transferring the data between the microprocessor and the Command byte For each data transfer, a Command Byte is initiated to specify which register is accessed. This is to determine whether a read, write, or test cycle is operated and whether a single byte or burst mode transfer is to occur. Refer to the table shown below and follow the steps to write the data to the chip.

One is in single-byte mode ad the other is in multiple-byte mode. These bits control the operation of the oscillator and so data can be written to the register array. These two bits should first be specified in order to read from and write to the register array properly. When it is set as? There are eight registers used to control the month data, etc.

The test mode is used by Holtek only for testing purposes. If used generally, unpredictable conditions may occur. Data can be written into the designated register only if the Write Protect signal WP is set to logic 0.

The Write Protect Register should be set first before restarting the system or before writing the new data to the system, and it should set as logic 1 in the read cycle.

The Write Protect bit cannot be written to in the burst mode. When this bit is set to logic 1, the clock oscillator is stopped and the chip goes into a low-power standby mode. When this bit is written to logic 0, the clock will start. When this bit is in high level, the hour mode is selected otherwise it? When D5 is logic 1, it is PM, otherwise it? The REST pin is also used to terminate either single-byte or burst mode data format.

The input signal of SCLK is a sequence of a falling edge followed by a rising edge and it is used to synchronize the register data whether read or write. For data input, the data must be read after the rising edge of SCLK.

The data transfer is illustrated on the next page. Additional SCLK cycles are ignored. Data inputs are entered starting with bit 0. The data bit outputs on the falling edge of the next eight SCLK cycles. Note that the first data bit to be transmitted on the first falling edge after the last bit of the read command byte is written.

Data outputs are read starting with bit 0. In order to obtain the correct frequency, two additional load capacities C1, C2 are needed. The value of the capacity depends on how accurate the crystal is. We suggest that you can follow the table on the next page. The REST pin must be taken low again after the transfer operation is completed.

In total, 16 clock pulses are needed for a single byte mode and 72 for burst mode. Both input and output data starts with bit 0. Then, choose either single mode or burst mode to input the data. The read or write operating flowcharts are shown on the next page.

Refer to the suggestion table of page 7. Headquarters No. Tel: Fax: Holtek Semiconductor Inc. Taipei Office 5F, No. The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Holtek assumes no responsibility arising from the use of the specifications described. The applications mentioned herein are used solely for the purpose of illustration and Holtek makes no warranty or representation that such applications will be suitable without further modification, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise.

Holtek reserves the right to alter its products without prior notification.


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