Micro crystal RV-8063-C7, Applications Manual

Page: 30 / 58

Micro Crystal
Ultra Small Real-Time Clock Module with SPI-Bus Interface RV-8063-C7
October 2018 30/58 Rev. 1.1
MINUTE AND HALF MINUTE INTERRUPT FUNCTION 4.8.
The Minute Interrupt (bit MI) and Half Minute Interrupt (bit HMI) are pre-defined timers for generating interrupt
pulses on pin
INT
̅̅̅̅̅
(see following Figure). The timers are running in sync with the seconds counter (see TIME AND
DATE REGISTERS, 04h - Seconds).
The minute and half minute interrupts must only be used when the frequency offset is set to normal mode (MODE =
0), see FREQUENCY OFFSET COMPENSATION. In normal mode, the interrupt pulses on pin
INT
̅̅̅̅̅
are 15.625 ms
wide.
When starting MI, the first interrupt will be generated after 1 second to 59 seconds. When starting HMI, the first
interrupt will be generated after 1 second to 29 seconds.
Subsequent periods do not have such a delay. The timers can be enabled independently from one another.
However, a Minute Interrupt enabled on top of a Half Minute Interrupt is not distinguishable.
INT
̅̅̅̅̅
example for MI:
seconds counter
minutes counter
INT when MI enabled
TF when MI enabled
58 59 59 00 00 01
11 12
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
≈
In this example, the TF flag is not cleared after an interrupt and the pin
INT
̅̅̅̅̅
is set to Pulse Mode
(TI_TP bit = 1).
Effect of bits MI and HMI on
INT
̅̅̅̅̅
generation:
Minute Interrupt (bit MI) Half Minute Interrupt (bit HMI) Result
0 0 No interrupt generated
1 0 Interrupt every minute
0 1
Interrupt every 30 seconds
1 1
The duration of the timer is affected by the register Offset (see CONTROL REGISTERS, 02h
– Offset Register).
Only when OFFSET has the value 00h the periods are consistent.
PULSE GENERATOR 1 4.8.1.
When the Timer Pulse Mode is activated (TI_TP = 1) the Pulse Generator 1 for the HMI and MI Interrupt Function
uses an internal clock.
The minute and half minute interrupts must only be used when the frequency offset is set to normal mode (MODE =
0). In normal mode, the interrupt pulses on pin
INT
̅̅̅̅̅
are 15.625 ms wide. TF and
INT
̅̅̅̅̅
become active simultaneously.