Rainbow Electronics DS1615 User Manual

Page 4

DS1615

4 of 24

I/O (3-wire Input/Output) - The I/O pin is the data Input/Output signal for the 3-wire synchronous
communications channel.

RST

(3-wire Reset Input) - The

RST

pin is the communications reset pin for the 3-wire synchronous

communications channel.

INT

(Interrupt Output) - The

INT

pin is an open drain active low output that can be connected to an

interrupt input of a microprocessor. The

INT

output remains low as long as the status bit causing the

interrupt is present and the corresponding interrupt-enable bit is set.

INSPEC

(Open Drain In-Specification Output) - This pin, in conjunction with the

OUTSPEC

pin, is

used to signal the status of the operation and data of the DS1615.

OUTSPEC

(Open Drain Out-of-Specification Out-put) - This pin, in conjunction with the

INSPEC

pin,

is used to signal the status of the operation and data of the DS1615.

(Start/Status Button Input) - The

pin provides two functions. First, when enabled as the datalog

start source (SE bit in Control register is a logic 1), the

pin is used to instruct the DS1615 to begin

recording temperature data based on the programmed start delay and data sample rate. The

pin must

be held low for at least 0.5 seconds for a datalog mission to begin. An external pullup resistor should be
connected to this pin.

Secondly, the

pin can be used to poll the status of the recorded data. After datalogging has begun, the

pin instructs the DS1615 to report the status of the recorded data via the

INSPEC

and

OUTSPEC

pins.

X1, X2 - Connections for a standard 32.768 kHz quartz crystal, Daiwa part number DT-26S or
equivalent. For greatest accuracy, the DS1615 must be used with a crystal that has a specified load
capacitance of 6 pF. There is no need for external capacitors or resistors. Note: X1 and X2 are very high
impedance nodes. It is recommended that they and the crystal be guard-ringed with ground and that high
frequency signals be kept away from the crystal area. For more information on crystal selection and
crystal layout considerations, please consult Application Note 58, Crystal Considerations with Dallas
Real Time Clocks.

NC (No Connect) - This pin should be left unconnected.

MEMORY

The memory map in Figure 2a shows the general organization of the DS1615. As can be seen in the
figure, the device is segmented into 32 byte pages. Pages 0 and 1 contain the Real Time Clock and
Control registers (see Figure 2b for more detail). The User NV RAM resides in page 2. Pages 17 to 19
are assigned to storing the alarm time stamps and durations. The temperature histogram bins begin at
page 64 and use up four pages. The temperature logging memory covers pages 128 to 191. Memory
pages 1, 3 to 16, 20 to 63, 68 to 127, and 192 and up are reserved for future extensions.

The end user can write only to the Real Time Clock and Control registers and the User NV RAM. The
rest of the memory map is read-only from the end users perspective.