Datasheet

Jon Waddington
67
Figure 4.7.4shows the transmission of the PCF8563’s minute register to the Propeller’s
input pin. The value of the 7
th
bit is not used in this register. The value of the register is
0x52, which converted from binary coded decimal is 52 minutes.
4.8 Real Time Clock
The testing of the clock showed that over long periods of time, the clock seemed to
become slightly out of sync by running too slow. After one month from setting the time
on the Information system, the time was out by approximately 4 minutes. T his could be
down to the crystal oscillator running at a slightly slower frequency than specified or it
could be the chip itself. This is not thought to be too much of a problem as it is very easy
to set the correct time again.
SCK
SDA
0
0
0
1
X
1
0
1
Acknowledge
Figure 4.7.4. I2C Waveform Sending the byte 0x52
0x52