參數(shù)資料
型號: RV5C387A
廠商: RICOH COMPANY LTD
元件分類: XO, clock
英文描述: I2C-bus Real-Time Clock ICs with Voltage Monitoring Function
中文描述: 0 TIMER(S), REAL TIME CLOCK, PDSO10
封裝: 4 X 2.90 MM, 1.20 MM HEIGHT, SSOP-10
文件頁數(shù): 25/42頁
文件大?。?/td> 363K
代理商: RV5C387A
PRELIMINARY RV5C387A
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14.1.5. Data Transmission under Special Condition
The RV5C387A holds the clock tentatively for duration from Start Condition to avoid invalid read or write
clock on carrying clock. When clock carried during this period, which will be adjusted within approx. 61
μ
s
from Stop Condition. To prevent invalid read or write, clock shall be made during one transmission
operation (from Start Condition to Stop Condition). When 0.5 to 1.0 second elapses after Start Condition,
any access to the RV5C387A is automatically released to release tentative hold of the clock, and access from
the CPU is forced to be terminated (The same action as made Stop Condition is received: automatic resume
function from I
2
C-Bus interface). Therefore, one access must be complete within 0.5 seconds. The
automatic resume function prevents delay in clock even if SCL is stopped from sudden failure of the system
during clock read operation.
Also a second Start Condition after the first Start Condition and before the Stop Condition is regarded
“Repeated Start Condition”. Therefore, when 0.5 to 1.0 seconds passed after the first Start Condition, an
access to the RV5C387A is automatically released.
If access is tried after automatic resume function is activated, no acknowledge signal will be output for writing
while FFh will be output for reading.
The user shall always be able to access the real-time clock as long as three conditions are met.
(1) No Stop Condition shall be generated until clock read/write is started and completed.
(2) One cycle read/write operation shall be complete within 0.5 seconds.
(3) Do not make Start Condition within 61
μ
s from Stop Condition. When clock is carried during the access,
which will be adjusted within approx. 61
μ
s from Stop Condition.
Bad example of reading from seconds to hours (invalid read)
(Start Condition)
(Read of seconds)
(read of minutes)
(Stop Condition)
(Start Condition)
(Read
of hour)
(Stop Condition)
Assuming read was started at 05:59:59 P.M. and while reading seconds and minutes the time advanced to
06:00:00 P.M. At this time second digit is hold so read the read as 05:59:59. Then the RV5C387A confirms
(Stop Condition) and carries second digit being hold and the time change to 06:00:00 P.M. Then, when the
hour digit is read, it changes to 6. The wrong results of 06:59:59 will be read.
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