NXP Semiconductors UM10301 PCF2123 - Manual (Page 28)

NXP Semiconductors
UM10301
User Manual PCF85x3, PCA8565 and PCF2123, PCA2125
UM10301_1 © NXP B.V. 2008. All rights reserved.
User manual Rev. 01 — 23 December 2008 28 of 52
Binary (BCD) HEX Register
Address Comments
0 0 0 0 1 0 0 1 09 word address 9 for minute alarm
0 0 0 1 0 1 0 1 15 09 minute alarm enabled and set to 15 minutes
1 0 0 0 0 0 0 0 80 0A hour alarm is disabled
1 0 0 0 0 0 0 0 80 0B day alarm is disabled
1 0 0 0 0 0 0 0 80 0C weekday alarm is disabled
generate I
2
C start condition (repeated start)
1 0 1 0 0 0 1 0 A2 I
2
C slave address, write
0 0 0 0 0 0 0 1 01 word address 1, next bytes are data
0 0 0 0 0 0 1 0 02 01 Control/status 2, clear alarm flag and enable alarm
interrupt
generate I
2
C stop condition
Remark: The interrupt is only set at the counter transition from 14 to 15. This is indicated
by the dashed line in Fig 11. The interrupt has to be reset by software.
Fig 11. Alarm function