PCF8563BS NXP [NXP Semiconductors], PCF8563BS Datasheet - Page 11

• Manufacturer Part Number: PCF8563BS
• Description: Real-time clock/calendar
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCF8563_6
Product data sheet
7.7 EXT_CLK test mode
Table 22.
Table 23.
Table 24.
A Test mode is available which allows for on-board testing. In such a mode it is possible to
set up test conditions and control the operation of the RTC.
The Test mode is entered by setting bit TEST1 in control_status_1 register. Then
pin CLKOUT becomes an input. The Test mode replaces the internal 64 Hz signal with the
signal applied to pin CLKOUT. Every 64 positive edges applied to pin CLKOUT will then
generate an increment of one second.
The signal applied to pin CLKOUT should have a minimum pulse width of 300 ns and a
minimum period of 1000 ns. The internal 64 Hz clock, now sourced from CLKOUT, is
divided down to 1 Hz by a 2
into a known state by using bit STOP. When bit STOP is set, the pre-scaler is reset to 0
(STOP must be cleared before the pre-scaler can operate again).
From a STOP condition, the first 1 second increment will take place after 32 positive
edges on CLKOUT. Thereafter, every 64 positive edges will cause a one-second
increment.
Remark: Entry into EXT_CLK test mode is not synchronized to the internal 64 Hz clock.
When entering the Test mode, no assumption as to the state of the pre-scaler can be
made.
Bit
7
6 to 2
1 to 0
TD1
0
0
1
1
Bit
7 to 0
Symbol
TE
x
TD[1:0]
Symbol
TIMER
Timer_control - Timer control register (address 0Eh) bit description
TD1 and TD0: Timer frequency selection
Timer - Timer value register (address 0Fh) bit description
Rev. 06 — 21 February 2008
Value
0
1
see
TD0
0
1
0
1
Value
00h to FFh
6
Table 23
divide chain called a pre-scaler. The pre-scaler can be set
Description
timer is disabled
timer is enabled
not relevant
timer source clock frequency select; these bits
determine the source clock for the countdown
timer; when not in use, TD[1:0] should be set
to 11 (
TIMER Source clock frequency
4096 Hz
64 Hz
1 Hz
1
Description
countdown value = n;
CountdownPeriod
60
Hz
1
60
Hz) for power saving
=
Real-time clock/calendar
-------------------------------------------------------------- -
SourceClockFrequency
PCF8563
© NXP B.V. 2008. All rights reserved.
n
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