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Timekeeping Registers

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logic edited this page Mar 15, 2011 · 11 revisions

Timekeeping Registers

Timekeeping registers from a variety of DS/Maxim RTC ICs.

DS1307

64 x 8, Serial, I²C Real-Time Clock

Applies to: DS1307

Datasheet

ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION RANGE
00h CH 10 Seconds Seconds Seconds 00–59
01h 0 10 Minutes Minutes Minutes 00–59
02h 0 12/24 AM/PM 10 Hour Hours Hours 1-12 +AM/PM 00-23
10 Hour
03h 0 0 0 0 0 Day Day 01–07
04h 0 0 10 Date Date Date 01–31
05h 0 0 0 10 Month Month Month 01-12
06h 10 Year Year Year 00–99
07h OUT 0 0 SQWE 0 0 RS1 RS0 Control —
08h–3Fh   RAM 56 x 8 00h-FFh

DS1337

I²C Serial Real-Time Clock

Applies to: DS1337, DS1337C

Datasheet

ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION RANGE
00h 0 10 Seconds Seconds Seconds 00–59
01h 0 10 Minutes Minutes Minutes 00–59
02h 0 12/24 AM/PM 10 Hour Hours Hours 1-12 +AM/PM 00-23
10 Hour
03h 0 0 0 0 0 Day Day 01–07
04h 0 0 10 Date Date Date 01–31
05h Century 0 0 10 Month Month Month/Century 01-12
06h 10 Year Year Year 00–99
07h A1M1 10 Seconds Seconds Alarm 1 Seconds 00–59
08h A1M2 10 Minutes Minutes Alarm 1 Minutes 00–59
09h A1M3 12/24 AM/PM 10 Hour Hours Alarm 1 Hours 1-12 +AM/PM 00-23
10 Hour
0Ah A1M4 DY/DT 0 0 0 Day Alarm 1 Day 1–7
Date Alarm 1 Date 01-31
0Bh A2M2 10 Minutes Minutes Alarm 2 Minutes 00–59
0Ch A2M3 12/24 AM/PM 10 Hour Hours Alarm 2 Hours 1-12 +AM/PM 00-23
10 Hour
0Dh A2M4 DY/DT 0 0 0 Day Alarm 2 Day 1–7
Date Alarm 2 Date 01-31
0Eh EOSC 0 0 RS2 RS1 INTCN A2IE A1IE Control —
0Fh OSF 0 0 0 0 0 A2F A1F Status —

DS1338

I²C RTC with 56-Byte NV RAM

Applies to: DS1338, DS1338C, DS1338U, DS1338Z

Datasheet

Notes: functionally identical to DS1307 except for addition of OSF (Oscillator Stop Flag) bit in the control register.

ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION RANGE
00h CH 10 Seconds Seconds Seconds 00–59
01h 0 10 Minutes Minutes Minutes 00–59
02h 0 12/24 AM/PM 10 Hour Hours Hours 1-12 +AM/PM 00-23
10 Hour
03h 0 0 0 0 0 Day Day 01–07
04h 0 0 10 Date Date Date 01–31
05h 0 0 0 10 Month Month Month 01-12
06h 10 Year Year Year 00–99
07h OUT 0 OSF SQWE 0 0 RS1 RS0 Control —
08h–3Fh   RAM 56 x 8 00h-FFh

DS1339

I²C Serial Real-Time Clock

Applies to: DS1339, DS1339C, DS1339U

Datasheet

Notes: functionally identical to DS1337 except for addition of BBSQI bit in the control register, and trickle charger register.

ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION RANGE
00h 0 10 Seconds Seconds Seconds 00–59
01h 0 10 Minutes Minutes Minutes 00–59
02h 0 12/24 AM/PM 10 Hour Hours Hours 1-12 +AM/PM 00-23
10 Hour
03h 0 0 0 0 0 Day Day 01–07
04h 0 0 10 Date Date Date 01–31
05h Century 0 0 10 Month Month Month/Century 01-12
06h 10 Year Year Year 00–99
07h A1M1 10 Seconds Seconds Alarm 1 Seconds 00–59
08h A1M2 10 Minutes Minutes Alarm 1 Minutes 00–59
09h A1M3 12/24 AM/PM 10 Hour Hours Alarm 1 Hours 1-12 +AM/PM 00-23
10 Hour
0Ah A1M4 DY/DT 0 0 0 Day Alarm 1 Day 1–7
Date Alarm 1 Date 01-31
0Bh A2M2 10 Minutes Minutes Alarm 2 Minutes 00–59
0Ch A2M3 12/24 AM/PM 10 Hour Hours Alarm 2 Hours 1-12 +AM/PM 00-23
10 Hour
0Dh A2M4 DY/DT 0 0 0 Day Alarm 2 Day 1–7
Date Alarm 2 Date 01-31
0Eh EOSC 0 BBSQI RS2 RS1 INTCN A2IE A1IE Control —
0Fh OSF 0 0 0 0 0 A2F A1F Status —
10h TCS3 TCS2 TCS1 TCS0 DS1 DS0 ROUT1 ROUT0 Trickle Charger —

DS1340

Low-Current I²C RTCs for High-ESR Crystals

Applies to: DS1340, DS1340C

Datasheet

Notes: Similar to DS1307.

  • EOSC (Enable Oscillator) is now at register 0x00 bit 7 instead of CH.
  • CEB (Century Enable Bit) added at 0x02 bit 7
  • CB (Century Bit) is now at 0x02 bit 6 instead of 12/24 switch.
  • Control register has changed significantly.
  • Trickle Charger register added.
  • OSF (Oscillator Stop Flag) added, in new Flag register.
ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION RANGE
00h EOSC 10 Seconds Seconds Seconds 00–59
01h 0 10 Minutes Minutes Minutes 00–59
02h CEB CB 10 Hours Hours Century/Hours 0-1; 00-23
03h 0 0 0 0 0 Day Day 01–07
04h 0 0 10 Date Date Date 01–31
05h 0 0 0 10 Month Month Month 01-12
06h 10 Year Year Year 00–99
07h OUT FT S CAL4 CAL3 CAL2 CAL1 CAL0 Control —
08h TCS3 TCS2 TCS1 TCS0 DS1 DS0 ROUT1 ROUT0 Trickle Charger —
09h OSF 0 0 0 0 0 0 0 Flag —

DS1341, DS1342

Low-Current I²C RTCs for High-ESR Crystals

Applies to: DS1341, DS1342

Datasheet

Notes: Similar to DS1337, with differences in control and status registers.

  • EGFIL (Enable Glitch Filter) added to control register
  • DOSF (Disable Oscillator Stop Flag), LOS (Loss Of Signal), CLKSEL1/2 (Select Clock Source), and ECLK (Enable External Clock Input) added to control/status register.
ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION RANGE
00h 0 10 Seconds Seconds Seconds 00–59
01h 0 10 Minutes Minutes Minutes 00–59
02h 0 12/24 AM/PM 10 Hour Hours Hours 1-12 +AM/PM 00-23
10 Hour
03h 0 0 0 0 0 Day Day 01–07
04h 0 0 10 Date Date Date 01–31
05h Century 0 0 10 Month Month Month/Century 01-12
06h 10 Year Year Year 00–99
07h A1M1 10 Seconds Seconds Alarm 1 Seconds 00–59
08h A1M2 10 Minutes Minutes Alarm 1 Minutes 00–59
09h A1M3 12/24 AM/PM 10 Hour Hours Alarm 1 Hours 1-12 +AM/PM 00-23
10 Hour
0Ah A1M4 DY/DT 0 0 0 Day Alarm 1 Day 1–7
Date Alarm 1 Date 01-31
0Bh A2M2 10 Minutes Minutes Alarm 2 Minutes 00–59
0Ch A2M3 12/24 AM/PM 10 Hour Hours Alarm 2 Hours 1-12 +AM/PM 00-23
10 Hour
0Dh A2M4 DY/DT 0 0 0 Day Alarm 2 Day 1–7
Date Alarm 2 Date 01-31
0Eh EOSC 0 EGFIL RS2 RS1 INTCN A2IE A1IE Control —
0Fh OSF DOSF LOS CLKSEL2 CLKSEL1 ECLK A2F A1F Control/Status —
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