DS1923-F5# Maxim Integrated Products, DS1923-F5# Datasheet - Page 17

• Manufacturer Part Number: DS1923-F5#
• Description: IBUTTON TEMP/HUMIDITY LOGGER F5
• Manufacturer: Maxim Integrated Products
• Series: iButton®r

Specifications of DS1923-F5#

• Rohs Information: IButton RoHS Compliance Plan
• Memory Size: 512B
• Memory Type: NVSRAM (Non-Volatile SRAM)
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption

The RTC and calendar information is accessed by
reading/writing the appropriate bytes in the register
page, address 0200h to 0205h. For readings to be
valid, all RTC registers must be read sequentially start-
ing at address 0200h. Some of the RTC bits are set to
0. These bits always read 0 regardless of how they are
written. The number representation of the RTC registers
is binary-coded decimal (BCD) format.
The DS1923’s RTC can run in either 12hr or 24hr mode.
Bit 6 of the Hours register (address 0202h) is defined
as the 12hr or 24hr mode select bit. When high, the
12hr mode is selected. In the 12hr mode, bit 5 is the
AM/PM bit with logic 1 being PM. In the 24hr mode, bit
5 is the 20hr bit (20hr to 23hr). The CENT bit, bit 7 of
the Months register, can be written by the user. This bit
changes its state when the years counter transitions
from 99 to 00.
The calendar logic is designed to automatically com-
pensate for leap years. For every year value that is
either 00 or a multiple of 4, the device adds a 29th of
February. This works correctly up to (but not including)
the year 2100.
Note: During a mission, there is only read access to these registers. Bit cells marked “0” always read 0 and cannot be written to 1.
Note: During a mission, there is only read access to these registers. Bit cells marked “0” always read 0 and cannot be written to 1.
ADDRESS
ADDRESS
0200h
0201h
0202h
0203h
0204h
0205h
0206h
0207h
Detailed Register Descriptions
Hygrochron Temperature/Humidity Logger
CENT
BIT 7
BIT 7
______________________________________________________________________________________
0
0
0
0
0
Timekeeping and Calendar
12/24
BIT 6
BIT 6
iButton with 8KB Data-Log Memory
0
0
0
10 Years
10 Seconds
10 Minutes
20 Hour
AM/PM
BIT 5
BIT 5
0
10 Date
10 Months
10 Hour
BIT 4
BIT 4
Sample Rate Low
The content of the Sample Rate register (addresses
0206h, 0207h) specifies the time elapse (in seconds if
EHSS = 1, or minutes if EHSS = 0) between two tem-
perature/humidity-logging events. The sample rate can
be any value from 1 to 16,383, coded as an unsigned
14-bit binary number. If EHSS = 1, the shortest time
between logging events is 1s and the longest (sample
rate = 3FFFh) is 4.55hr. If EHSS = 0, the shortest is
1min and the longest time is 273.05hr (sample rate =
3FFFh). The EHSS bit is located in the RTC Control reg-
ister at address 0212h. It is important that the user sets
the EHSS bit accordingly while setting the Sample Rate
register. Writing a sample rate of 0000h results in a
sample rate = 0001h, causing the DS1923 to log the
temperature either every minute or every second
depending upon the state of the EHSS bit.
BIT 3
BIT 3
Sample Rate High
Sample Rate Register Bitmap
BIT 2
BIT 2
Single Seconds
Single Minutes
Single Months
Single Hours
Single Years
Single Date
RTC Registers Bitmap
BIT 1
BIT 1
Sample Rate
BIT 0
BIT 0
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