VMA301
V. 02 – 14/05/2018
3
©Velleman nv
5.
Overview
The DS1302 trickle-charge timekeeping chip contains a real-time clock/calendar and 31 bytes of static RAM.
It communicates with a microprocessor via a simple serial interface. The real-time clock/calendar provides
seconds, minutes, hours, day, date, month, and year information. The end of the month date is automatically
adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either
the 24-hour or 12-hour format with an AM/PM indicator.
Arduino
®
VMA301
D5
CE
D6
I/O
D7
SCLK
5 V
VCC
GND
GND
power supply ................................................................................................... 1 x CR2032
TTL compatible .................................................................................................. VCC = 5 V
temperature range ...................................................................................... 0 °C to +70 °C
6.
Pin Layout
CE
Input. The CE signal must be asserted high during a read or a write. This pin has an internal
40 kΩ (typ) pulldown resistor to ground. Note: Previous data sheet revisions referred to CE as
RST
. The functionality of the pin has not changed.
I/O
Input/push-pull output. The I/O pin is the bidirectional data pin for the 3-wire interface. This pin
has an internal 40 kΩ (typ) pulldown resistor to ground.
SCLK
Input. SCLK is used to synchronize data movement on the serial interface. This pin has an internal
40 kΩ (typ) pulldown resistor to ground.
VCC
Primary power supply pin in dual supply configuration. V
CC1
is connected to a backup source to
maintain the time and date in the absence of primary power. The VMA301 operates from the
larger of V
CC1
or V
CC2
. When V
CC2
is greater than V
CC1
+ 0.2 V, V
CC2
powers the VMA301. When
V
CC2
is less than V
CC1
, V
CC1
powers the VMA301.
GND
Ground.