M48T201V-85MH1TR View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
M48T201V-85MH1TR Datasheet PDF : 37 Pages
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M48T201Y, M48T201V
Clock operation
Note:
In order to perform a software reset of the watchdog timer, the original timeout period can be
written into the watchdog register, effectively restarting the countdown cycle.
Should the watchdog timer time out, and the WDS bit is programmed to output an interrupt,
a value of 00h needs to be written to the watchdog register in order to clear the IRQ/FT pin.
This will also disable the watchdog function until it is again programmed correctly. A READ
of the flags register will reset the watchdog flag (bit D7; register 7FFF0h).
The watchdog function is automatically disabled upon power-down and the watchdog
register is cleared. If the watchdog function is set to output to the IRQ/FT pin and the
frequency test function is activated, the watchdog or alarm function prevails and the
frequency test function is denied.
The user must transition the address (or toggle chip enable) to see the flag bit change.
3.7
Square wave output
The M48T201Y/V offers the user a programmable square wave function which is output on
the SQW pin. RS3-RS0 bits located in 7FFF0h establish the square wave output frequency.
These frequencies are listed in Table 7. Once the selection of the SQW frequency has been
completed, the SQW pin can be turned on and off under software control with the square
wave enable bit (SQWE) located in register 7FFF6h.
Table 7.
Square wave output frequency
Square wave bits
RS3
RS2
RS1
RS0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
Square wave
Frequency
Units
Hi-Z
-
32.768
kHz
8.192
kHz
4.096
kHz
2.048
kHz
1.024
kHz
512
Hz
256
Hz
128
Hz
64
Hz
32
Hz
16
Hz
8
Hz
4
Hz
2
Hz
1
Hz
21/37
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